Styles of Experimental Reasoning in Early Modern Chemistry

Home , Chemical revolution, Corpuscularianism

Victor Dan Boantza

A thesis submitted in conformity with requirements for the degree of Doctor of Philosophy Institute for the History and Philosophy of Science and Technology University of Toronto

Styles of Experimental Reasoning in Early Modern Chemistry

Victor Dan Boantza

Doctor of Philosophy

Institute for the History and Philosophy of Science and Technology University of Toronto

2009 Abstract The science of chemistry has undergone two major transformative changes during the early modern period, both closely related to two of the most revolutionary episodes in the history of Western science. The dissertation consists of a historical-analytical comparative exploration of early modern chemical thought and practice based on two series of interconnected case studies related, respectively, to the seventeenth-century

Scientific Revolution and the eighteenth-century Chemical Revolution.

Although rarely considered together in the context of the history of chemistry, during both Revolutions, similar forces combined to generate crises in chemical knowledge and practice, to use a well-known Kuhnian notion. Differences in nature and historical evolution notwithstanding, both instances featured attempts at quantification and physicalist reductions of chemistry: during the 1660s-1680s Boyle advanced a reconciliation of chymical experimental knowledge with the budding mechanical philosophy, predicated upon the physically governed laws of matter and motion; during the last third of the eighteenth-century, Lavoisier (et al.) submitted chemical phenomena to the

‘rule of the balance’, as a part of an all-encompassing experimentalist, theoretical and linguistic reformation anchored in the conservation of weight principle.

Concerned with the ‘losers’ (the chemists par excellence) rather than the ‘winners’, the study analyzes the reactions of leading contemporary chemists. Part I explores a critique of Boyle’s experimental philosophy and mechanist agendas conducted by French

Royal Academician Samuel C. Duclos (1598-1685). In face of what he perceived as the unwarranted mechanical reduction of chymistry, Duclos set out to rehabilitate traditional chemical philosophy, drawing upon Paracelsian and Helmontian notions. This critique

(1667-68) sparked a lengthy debate over cohesion and coagulation between academicians of diverging chymical and physical persuasions, culminating in the 1669 dispute over pesanteur and gravity. Part II examines Joseph Priestley’s and Richard Kirwan’s defenses of phlogistic chemistry and their respective versions of chemical experimentalism, followed by a broader contextualizing inquiry into the nature of the metaphysical, epistemological and rhetorical commitments that were defended under the banner of the phlogistic chemical worldview during the late stages of the Chemical Revolution.

The category of Style of Experimental Reasoning (SER)—derived from A. C.

Crombie and I. Hacking—is introduced, developed and used for capturing salient features of early modern chemical knowledge as it was dynamically molded at the confluence of discourse and practice. In contrasting contemporary chemists’ reactions to the physicalist challenges, the two revolutionary episodes mutually illuminate each other; the category of

SER affords a reconstruction of the chemists’ unique realm of action and subsequent production of chemical knowledge. Inquiring into the dialectics of continuity-versus- discontinuity between the two perceived Revolutions, the study redraws the line between the ‘chymical’ and the ‘physical’, providing a new understanding of the metaphysical and experimental complexities involved in the birth of modern chemistry.

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Acknowledgements

It is a great pleasure to acknowledge the support of the following people and institutions.

I thank my family for supporting me during my graduate studies. Special thanks go to my mother, for her constant interest and concern; her unfailing confidence in me has been a particular source of encouragement and motivation. I thank Raphael Steinitz for his keen interest in my work and progress, for his support, and for many interesting conversations. Daphna Sharan has stood by me for many years, patiently reading all my papers since my years as an undergraduate at the Ben-Gurion University of the Negev in

Israel. I am deeply grateful for her support, insights, and advice. Her presence in my life has kept me grounded.

I am grateful for the financial support through scholarships and grants without which my research would have been impossible. My thanks go to the University of

Toronto Connaught Scholarship Fund, the Ontario Graduate Scholarship Program, the

IHPST, and the Chemical Heritage Foundation for the Roy G. Neville Fellowship.

I thank Janis Langins and Brian Baigrie for their suggestions and comments on my doctoral research. Lawrence Principe has been a source of inspiration in both his work and in person. Special thanks go to David Knight for his comments on my thesis and for stimulating discussions. The many good times with my friends and colleagues have kept the writing of this dissertation in perspective. In particular, I thank Arik Sherman, Amir

Karton, Nimrod Maman, Merom Kalie, Martha Harris, Conor Burns, Brigit Ramsingh, and

Erich Weidenhammer.

Two scholars and friends, Ofer Gal and Alice Stroup, deserve particular mention.

Ofer Gal has introduced me to the History and Philosophy of Science in 1999 and since that time he has been a constant source of information, critical comment, and assistance; I am truly grateful for the many things he had taught me over the years, and for his unsparing moral and intellectual support. Alice Stroup began by generously sharing with me, a few years ago, her archival material and conjectures on chemistry and the early

Parisian Royal Academy of Sciences; since then she shared freely her remarkably wide knowledge of the history of early modern science and French history, has read and commented on several drafts and papers, and provided me with a vital source of intellectual enthusiasm and originality.

Lastly, and most significantly, I thank my doctoral supervisor, Trevor H. Levere, a fountain of knowledge and experience, and my chief mentor over the past six years. I am deeply grateful for his advice, interest, generosity, and concern, and above all for his unique perceptiveness as a teacher, as well as for the intellectual environment and professional standards he provided me with during my graduate studies. Much of what I have learned and achieved as a doctoral student career owes to him.

TABLE OF CONTENTS

Introduction Overview 1 Methodological Framework: Objectives and Subjects Two “Revolutions”, One “Normal Science” and The “Crises” of Early Modern Chemistry 8 Quantification and Physicalist Reduction: A “Crisis-Provoking Problem” 14 The Chymical vs. the Physical: Reactions and Actions in Early Modern Chemistry Thematic Outline 22 From Reaction to Action: Style of Experimental Reasoning (SER) 28 PART I: CHYMISTRY AND THE SCIENTIFIC REVOLUTION Chapter 1 Chemical Philosophy and Boyle’s Philosophical Chemistry: Duclos Reads Boyle Background Samuel C. Duclos and Chymistry at the Early Académie 39 “Precise Speculations” and “Sensible Operations” 47 The Crisis of Chymical Principles 53 “Out of the Strong Came Something Sweet” 58 Duclos’s Principles 73 Particles of Saltpetre 79 Duclos on Boyle’s “Un-Succeeding Experiments” 93 Alkahest, Corpuscles and Fire 102 From Cohesion to Pesanteur 120 Conclusion and Interlude PART II: CHEMISTRY AND THE CHEMICAL REVOLUTION Chapter 2 Collecting Airs and Ideas: Priestley’s Style of Experimental Reasoning Introduction: Enduring Historiographic Difficulties 144 Background to Priestley’s Chemical Practice and Writing(s) 150 Experimental Commitments: The Case of Nitrous Air 154 The Science of Making and the Making of Science: Priestley’s SER 166 Conclusion 176 Excursus: Rereading Priestley Out of (traditional) Context 178 Chapter 3 Richard Kirwan’s “Ingenious Modifications… Into the Theory of Phlogiston” Introduction: History and Historiography 182 Phlogistic Transmutations and the Metaphysics of Pneumatic Entities 190 The Phlogistic Constitution and Role of Heat 200 Kirwan Enters the Phlogistic Arena: Innovations and Renovations 212

Conclusion 230 Chapter 4 Chemical Uniformity and the Rise of a “False Shew of Simplicity” 232 Introduction 232 “Red Vapours” vs. “Absolute facts” 236 “Certain Quantities” vs. “Proportions” 249 The Force of affinity and Affinity as a Force 253 Uniformity vs. Simplicity 259 Conclusion 265 “LAWS OF ANOTHER ORDER”: CONCLUDING REMARKS 267 BIBLIOGRAPHY 278

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List of Figures

P. 212: Figure 1: Adair Crawford’s conceptual representation of the relationship between “heat capacity” and “absolute heat” in two bodies or “quantitative matter.” Crawford, A. Experiments and Observations on Animal Heat, London: J. Murray & J. Sewell, 1779.

P. 214: Figure 2: Richard Kirwan’s table of specific heats. Reproduced in W. Cleghorn’s De igne, 1779, trans. & comm. by D. McKie & N. H. de V. Heathcote. London, 1960. (reprinted in Annals of Science 14.1, 1958)

P. 255: Figure 3: Table of “Single Elective Attractions” from Bergman’s Dissertation on Elective Attractions, London: J. Murray, 1785 versus Lavoisier’s ”table of oxygenous principle” from Kirwan’s Essay on Phlogiston and the Constitution of Acids, London: J. Johnson, 1789.

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INTRODUCTION

OVERVIEW

The science of chemistry has undergone two major transformative changes during the early modern period, both closely related to two of the most revolutionary episodes in the history of Western science. These two changes comprise the focal points of this study while marking its chronological boundaries. What follows is a historical and analytical comparative exploration of early modern chemical thought and practice based on two series of interconnected case studies each related, respectively, to what we have come to know as the seventeenth-century Scientific Revolution and the eighteenth-century

Chemical Revolution.

In his Origin of Modern Science, Herbert Butterfield stated that,

the emergence of chemistry as a science is remarkably late, that the chemistry of Boyle and Hooke may not have taken the shortest possible route to arrive at Lavoisier, and that the interposition of the phlogistic theory made the transition more difficult rather than more easy.1

Butterfield’s remark was designed as part of a broader argument, which revolved around a particular notion that has later come to be regarded as a high symbol of positivistic historiography and formed the target of numerous attacks. I refer to his idea of a

“postponed revolution in chemistry,” according to which while astronomy, mathematics, mechanics—the hard sciences—and even physiology have been ‘modernized’ sometime during the sixteenth- and seventeenth-centuries, chemistry, despite luminaries such as

Paracelsus and Van Helmont, Boyle and Stahl, Hales and Black, had to wait for another

1 Butterfield (1957), pp. 210-211.

century before Lavoisier disburdened it from the theoretical chains of the phlogiston theory, delivering it from pseudo-scientific darkness into scientific light. I am not interested in reacting against or evaluating Butterfield’s view, although his awareness that

“such speculations certainly have their dangers”—a statement immediately preceding the abovementioned remark—is worth noting.2 Instead, I wish to employ his comment as a template against which to establish some of my general aims.

The Scientific and Chemical Revolutions are rarely considered together, either in general surveys of the history of science, in more specific histories of early modern science, or in the relatively few studies dedicated to or addressing the history of early modern chemistry.3 For a number of reasons, some of which I discuss later, the two events are considered, by most historians of science, to be virtually unrelated, their subject matter being so different.4 Sharing, however, a formal similarity—especially as associated with the metaphor of the scientific revolution, forcefully advanced by Thomas Kuhn and others—from a philosophical perspective, the two episodes are perceived as closely related and discussed as such.5 Butterfield’s general survey of The Origins of Modern Science,

1300-1800, is an exception, pointing out a connection between the two Revolutions,

2 Butterfield (1957), pp. 210-211. 3 For general histories of science see, for instance, Bowler and Morus (2005); Cohen (1985). For general histories of chemistry see: Partington (1957); Leicester (1956); Brock (1992); Levere (2001). Knight (1992) provides a singular, thematically oriented, approach; Cf. Siegfried (2002), which traces the single theme of ‘chemical composition’ but exhibits the same tendency of treating the two revolutions as disparate. Similar tendencies can be observed in Crosland (1978). 4 Two recent exceptions are Kim (2003) and Roos (2007) in both of which the narratives include discussions of chemistry during both Revolutions and some links and associations are hinted at. Both studies, however, trace the evolution of particular chemical entities during the early modern era, ‘chemical affinity’ in French chemistry and ‘salt’ in British chemistry and medicine, respectively. 5 For the locus classicus of this interpretation see Kuhn (1962).

although, ironically, it does so by denying the revolutionary nature of one of them, insofar as chemistry is concerned. On Butterfield’s account, early modern chemistry had undergone merely one, “postponed revolution,” which we identify as the eighteenth- century Chemical Revolution. Despite its popularity, the ‘scientific revolution’ is a mooted concept, in both its generic and particular versions.6 For now, what I take from

Butterfield—which is far from self-evident7—is the combined concern with both the seventeenth-century Scientific Revolution and the eighteenth-century Chemical Revolution in the context of the history of chemistry. But here the similarity ends; the rest of

Butterfield’s message serves me best when turned inside out.

Butterfield linked the two Revolutions as part of a paradoxical claim according to which chemistry could have acquired the status of a modern science as early as the times

“of Boyle and Hooke,” had their contributions in the field of pneumatics been recognized sooner and applied to chemistry. This, however, failed to happen and the change was

6 The generic ‘scientific revolution’ is usually taken to designate episodes of substantial change in science; examples include the astronomical, Copernican, Newtonian, chemical, Darwinian or Einsteinian revolutions. In its particular usage, the ‘Scientific Revolution’ refers specifically to the major changes in the study and interpretation of the natural world, especially in the Europe; the commonplace chronology of the event is 1450-1700, beginning with Copernicus and culminating with Newton. See Cohen (1994). For the origins and use of the concept of ‘scientific revolution’ see Cohen (1976); Lindberg (1990). Although widely used, the notion of a scientific revolution denoting a particular set of shifts in sixteenth- and seventeenth-century Europe has been recently challenged. See Fores (1983); Shapin (1996), who opens provocatively: “There was no such thing as the Scientific Revolution and this is a book about it.” (p. 1). 7 Golinski, for instance, has aptly observed that, “any proposal to examine the relationship between chemistry and the Scientific Revolution of the seventeenth century raises immediate problems of historiography.” Golinski (1990), p. 367. Debus, on the other hand, has been one of the few longtime proponents of the study of chemistry during the Scientific Revolution, attempting to shift the historiographic focus away from the eighteenth-century Chemical Revolution. Reflecting upon close to four decades of scholarship, he had recently pointed out the problem again: “my own interests then as now centered on the same chronological period of interest to those working on problems considered mainstream in the Scientific Revolution, but instead of Copernicus, I became interested in his contemporary, Paracelsus, and instead of Galileo, I turned to the chemist and physician, van Helmont.” Debus (2001), p. xiv. See also Debus (1990).

“postponed.” Boyle and Hooke’s contributions did not follow “the shortest possible route to arrive at Lavoisier” due to the “interposition of the phlogistic theory,” which had a retarding effect and impeded the progress of chemical knowledge. Despite this, Butterfield allowed, “it may have had the effect of making the conservative view more manageable for a certain period.”8 On this account, chemistry seems to have been revolutionized and modernized, perhaps implicitly, or perhaps in potentiality (as opposed to actuality) during the seventeenth-century, yet the full-fledged manifestation of that revolution came about only a century later when Lavoisier succeeded in laying the “phlogistic theory” to rest, while capitalizing on the century-old contributions of Boyle and Hooke in pneumatics, thus bringing about the Chemical Revolution of the late eighteenth-century. The teleological features of Butterfield’s account are explicit: the revolutionary seed, sown in the late

1600s, struck roots and sprouted only in the late 1700s.

The “chemistry of Boyle” as well as that of Lavoisier play a significant role in my analysis, yet only insofar as their interpretation is instrumental in elucidating the ways by which some of their opponents and critics, seventeenth- and eighteenth-century chemists, to whom I refer in general as either ‘traditional chemists’ or sometimes as chemists par excellence—acted and thought as part of their chemical practice.9 I discuss the nature of

8 Butterfield (1957), p. 211. 9 By chemists or chemical practitioners par excellence I mean, in a most general sense, natural philosophers who during the Scientific Revolution reacted against the mechanization of chymistry while defending the traditional ‘chemical philosophy’ that was informed by a blend of alchemy, Paracelsianism, Neo-Platonism, natural magic and Helmontianism. The coinage of ‘chemical philosophy’ is most widely identified with the work of Debus; see Debus (2002). In the context of the Chemical Revolution, the reference is to those who reacted against the French chemical reformation while defending phlogistic notions, informed by a complex mix of Stahlian principles, implicit alchemical agendas, chemical affinity and the chemistry of gases. See Holmes (1989); Fichman (1971); Donovan (1988); Duncan (1996).

the transition and consider the possibility of a route by which chemical knowledge may have proceeded over the period separating the two revolutions, yet I do not presuppose any continuity between the episodes; nor do I assume discontinuity. Instead, I explore critically and seek to establish the dynamics between the two elements—continuity versus discontinuity—which underlay that transition. Finally, phlogistic theory, as the leading chemical theoretical and practical framework employed by late eighteenth-century British and Continental pneumatic chemical practitioners alike, is central to my discussion of the

Chemical Revolution. Yet I stay away from attempts to establish whether such a theory functioned as an impediment or catalyst to the development of chemical knowledge.

My interest in “phlogistic theory” or in phlogiston as a theoretical entity per se is in fact limited, not least since by the latter half of the eighteenth-century and especially by the

1770s and 1780s the notion of a “phlogistic theory,” predicated upon an assumption of a unified theoretical whole, possessed of a well-defined referent, is virtually inapplicable.10

Owing in part to Lavoisier’s own rhetorical attacks on phlogiston as a straw-man, accompanied by decades of positivist scholarship, phlogiston theory has been commonly identified as Lavoisier’s major target and that of his collaborators, the Lavoisians. This is an oversimplified view, misrepresenting finer aspects of phlogistic thought and practice.11

Within a theoretical context, during the Chemical Revolution, phlogiston or “phlogistic theory” have been employed in various ways—metaphysically, epistemologically and

10 The notion of a unified ‘theory of phlogiston’ is doubtful in any case. ‘Phlogiston’, as a chemical entity, assumed many forms and was employed in various fashions throughout the eighteenth-century for the explanations of many chemical phenomena. Save for a general commitment to its meaning as a universal constituent of inflammable bodies, it is difficult to discern one clear theoretical framework within which it was defined and employed. See, for instance, Partington & McKie (1981); Holmes (2000a). 11 The most classical instance of this line of thought can be seen in Conant (1950).

experimentally—as I show in chapter 3 in reconstructing the sources and origins of what comprised the closest version of a full-fledged “phlogistic theory,” that of the Anglo-Irish natural philosopher Richard Kirwan.12 Coming to the fore during the 1780s, Kirwan’s version of phlogiston theory also represents, almost by default, a quintessential phlogistic defense—a subject about which much has been said.13 With respect to chemistry during the Chemical Revolution, my attempt is to uncover and establish salient features of

“phlogistic” chemistry, as related to thought and practice and the way they bear upon each other in the production of chemical-pneumatic knowledge. I am subsequently interested in the set of ontological and experimental commitments assumed by leading proponents of various phlogistic views and their interconnectedness, as gleaned from various debates, changes and transformations generated by and within the Chemical Revolution. The same types of goals and intents apply to my treatment of chymistry during the Scientific

Revolution.14 Butterfield, in line with contemporary postwar historiography highlighted

“phlogistic theory” alongside Boyle’s theoretical contributions to pneumatics. My focus,

12 See Boantza (2008); Holmes (2000a); Holmes (2000b). 13 See, for instance, Partington & McKie (1981); Boantza (2008), pp. 310-314; Boantza (2007a), pp. 506-508. 14 A note on terminology and my use of the terms ‘chemistry’ and ‘chymistry’ throughout the study: I use ‘chymistry’ as synonymous with (al)chemistry, denoting the transitional phase (especially the sixteenth- and seventeenth-centuries) bridging classical and medieval alchemy with modern chemistry. See Principe & Newman (1998). Since both the Scientific and the Chemical Revolution occurred during what is designated as the early modern era, I use ‘early modern chemistry’ to denote seventeenth- and eighteenth-century chemistry in general. I also use ‘chemistry’ and ‘chemical’ to refer to this field of inquiry in a general manner, outside of specific chronological frames of reference. In other words, ‘chymical’ and ‘chymistry’ are reserved for designating seventeenth-century ‘chemistry’ (and earlier) alone whereas most other cases—either later periods or general references—are denoted by ‘chemical’ or ‘chemistry’. Although Principe & Newman’s linguistic approach is considered standard nowadays, other historians have pointed to the irreducible complexity of the issue of alchemy’s ‘transformation’ into chemistry. See Abbri (2000).

in presenting micro-studies related to both the Scientific and Chemical Revolutions is the interplay between chemical theory and practice, between epistemology and experimental method; the dialectics of formation and reformation, innovation and renovation in the generation of early modern chemical knowledge.

At first view, read as a general statement of intent, the last sentence may seem to involve several methodological tensions worthy of particular attention. One difficulty derives from the disparity between the intrinsic restrictedness—chronological, geographic, thematic, etc.—of micro-studies and the possibility of merging them within a narrative that will transcend their locality and advance a broader argument concerning the nature of early modern chemistry. In other words, the problem is primarily one of dealing with the interplay between divergence and convergence, at both formal and substantive levels.

Another related difficulty has to do with the choice of focusing on two episodes, chronologically set apart by over a century. A less evident but equally important set of challenges derives from the attempt to deal with the interplay between chemical epistemology and what may be referred to as experimental method (see section From

Reaction to Action: Style of Experimental Reasoning).

The disparity, historiographical and chronological, serves to elucidate numerous core themes and events by projecting them against each other. Chemistry during the

Chemical Revolution is employed to illuminate chemistry during the Scientific Revolution, and the other way round. Such contrasting comparisons, however, depend upon the establishment of a well-defined conceptual framework. One way to fulfill this requirement is by underscoring conceptual similarities and employing them as guiding principles. In fact, the greater the apparent divergence between the subjects compared (conversely, the

less evident the common ground between them), the greater the relevance and service of such principles, which ultimately encapsulate the rationale underlying the entire analysis.

Formally dealing with scientific revolutionary episodes in the history of science we turn to

Kuhn’s Structure of Scientific Revolutions, and in particular to one of his most famous analytical tools: the notion of ‘crisis’ in science.

METHODOLOGICAL FRAMEWORK: OBJECTIVES AND SUBJECTS

Two “Revolutions”, One “Normal Science” and The “Crises” of Early Modern Chemistry

Despite vast differences in scope, subjects and evolutionary patterns, the science of chemistry was fundamentally challenged during both revolutionary episodes. This is widely recognized with regard to the Chemical Revolution. So much so, that the difficulties and woes of the phlogiston theory play a central role in the historiography of that episode. Going back to Butterfield or Conant, the shortcomings of phlogistic chemistry have been repeatedly discussed and examined in various studies of the Chemical

Revolution.15 Commonly contrasted with Lavoisier’s algebraic all-encompassing approach, phlogiston theory has been commemorated as one of the greatest theoretical slips of late early modern science. Although less widely researched, seventeenth-century chymistry has not been treated with greater historiographic charity: associated with the magical and irrational, it has been traditionally deemed as pseudo- or pre-scientific. As such, until recently, it has not received due scholarly attention and remains a much less

15 See, for instance, Musgrave (1976); Thagard (1990).

studied subject than eighteenth-century phlogistic chemistry.16 Lavoisier’s seventeenth- century counterpart, insofar as he assumed the historical persona of challenger or reformer of contemporary chemistry, was Robert Boyle. Owing to the complexity of the subject matter, as well as to Boyle’s lesser success in carrying through his intended reformation, of reconciling chymistry with the emerging mechanical philosophy, the nature of the seventeenth-century challenge to chymistry, and the corresponding reaction of the traditional chymical establishment, are usually either underrepresented or misrepresented.

I discuss this in Part I, at the center of which is an examination of a pivotal yet little known critique of Boyle, carried out by French royal academician Samuel Cottereau Duclos

(1598-1685), followed by an examination of some of this critique’s repercussions, set against the backdrop of the central tension between the traditional chemical philosophy and the rising mechanical doctrine.

Major differences notwithstanding, during both instances contemporary chemistry was profoundly shaken. The validity and applicability of its discursive and practical properties have been severely questioned; its foundations—whether at the level of matter theories, experimental philosophies or literary legacies and technologies—have been subjected to far-reaching skepticism. Early modern chemistry has undergone two major crises, to use Kuhn’s term. To further elicit Kuhnian terminology, the crisis imposed by

Lavoisier ended up undergoing a fully-fledged, if “postponed,” paradigmatic change, or in

Kuhn’s words, a scientific revolution; the one initiated by Boyle represents a less clear-cut

16 This is changing as studies of early modern chemistry have recently undergone a scholarly renaissance. See, for instance, Principe (1998); Newman (2006); Newman & Principe (2002); Moran (2005).

case and is more difficult to judge along strict Kuhnian guidelines. Kuhn acknowledged the sweeping seventeenth-century shift in natural philosophy as a scientific revolution but his view concerning the particular influence of that change on the science of chemistry is less clear. In general terms, however, it may be said that Boyle’s success in subjecting chymistry to the physically-governed laws of matter in motion does not match the magnitude of Lavoisier’s accomplishment of submitting chemical phenomena to “the rule of the balance.”17

Despite his wide-ranging use of examples and case studies from the history of science, Kuhn was not a professional historian of science. In his Structure—the locus of his foremost analytical framework, comprising concepts such as ‘normal science’, ‘crisis’,

‘anomaly’, ‘puzzle-solving’, ‘paradigm’, ‘scientific revolution’, etc—Kuhn enumerated only four complete revolutions in the history of science; only four integral replacements of a reigning paradigm with a novel one: the Copernican, Newtonian, Chemical and

Einsteinian Revolutions.

Although Kuhn’s historical account of the Chemical Revolution is simplistic, it is closely linked to his notion of crisis, representing the most significant historical example

Kuhn had used in the elaboration of this concept. For Kuhn, the short-lived, relatively localized, and climactic group of events and shifts comprising the Chemical Revolution— in particular the downfall of phlogiston and the rise of the oxygen theory of combustion and acidity—represented the essence of a scientific crisis or, of normal science under acute duress, while rivaled by a competing theory. In the case of the Copernican revolution, for

17 The phrase is found in Kim (2003), p. 380.

instance, “because the astronomical tradition was repeatedly interrupted from outside and because, in the absence of printing, communication between astronomers was restricted, these difficulties [“anomalies,” increasingly plaguing Ptolemaic astronomy] were only slowly recognized.” The Chemical Revolution, however, provides a “rather different example, [that of] the crisis that preceded the emergence of Lavoisier’s oxygen theory of combustion.” Whereas the Ptolemaic system seems to have undergone an implicit critical phase, “in the 1770’s, many factors combined to generate a crisis in chemistry.”18 Like

Butterfield, Kuhn stressed “the rise of pneumatic chemistry and the question of weight relations,” closely associated with “the increasing vagueness and decreasing utility of the phlogiston theory.” Writing almost two decades after Butterfield, Kuhn’s historical message is nearly identical. The former observed that, “the chemistry of Boyle and Hooke may not have taken the shortest possible route to arrive at Lavoisier” while the latter suggested that, “the theories of combustion by absorption from the atmosphere—theories developed in the seventeenth century by Ray, Hooke and Mayow—failed to get a sufficient hearing.”19 Although he seems to agree with Butterfield concerning the

“postponed” influence of Boyle’s pneumatic discoveries on Lavoisier, Kuhn acknowledged that the “atomistic, mechanical metaphysics… which provided so many fruitful new problems and new concepts to seventeenth century physics, proved a sterile and occasionally adverse intellectual climate for an understanding of the processes underlying chemical change.”20 He thus distinguished between Boyle’s pneumatic

18 Kuhn (1962), pp. 68-70; italics added. 19 Kuhn (1962), pp. 70-71, 76. 20 Kuhn (1952), p. 15.

observations as a precursor to Lavoisier’s reformation on the one hand, and his corpuscular matter theory, as a hindrance in the way of the advancement of early modern chemical knowledge on the other.

From a distinctly Kuhnian perspective, revolution and crisis are inextricably linked.

For my present purpose I find more use in the latter than in the former. Revolution, whether in its Kuhnian or in its general sense, marks out my general chronology and approach, signaling the form of my subject; crisis, however, brings us closer to its particular features and content. While not all crises evolve into revolutions, all revolutions are triggered by “the repeated failure of established normal scientists to handle the crisis situation.”21 Since all successful revolutions have been preceded by crises, the crisis may be said to be a highly critical part of a given scientific revolution. At the same time, a crisis designates another entity by excluding the actual process of transformation and coming into being of a revolution—the replacement of one scientific worldview with another—although the advent of a crisis usually signals it. Indeed, my general interest is in chemistry during the two Revolutions, but my particular concern lies in the critical phase that normal science undergoes (universally and periodically, according to Kuhn) and which is so forcefully represented by Kuhn’s notion of crisis. While not equally revolutionized, chemistry was equally challenged during the Scientific and Chemical Revolutions. This is a significant historical distinction; one that is implied by the Kuhnian conceptual scheme:

all crises close in one of three ways. Sometimes normal science ultimately proves able to handle the crisis-provoking problem despite the despair of those who have seen it as the end of an existing paradigm. On other occasions the problems resist even apparently radical new approaches.

21 Nickles (2003), p. 2.

Then scientists may conclude that no solution will be forthcoming in the present state of their field. The problem is labeled and set aside for a future generation with more developed tools. Or, finally, the case that will most concern us here, a crisis may end with the emergence of a new candidate for paradigm and with the ensuing battle over its acceptance.22

Staying with Kuhn’s threefold typology, it may be said that, insofar as chemical knowledge and practice were concerned, the Chemical Revolution is an exemplar of the third instance

(as Kuhn himself argued) whereas the Scientific Revolution represents a mixed instance, featuring traits from both the first and second examples. Whereas the concept of crisis embodies and preserves the crucial difference in the ways chemists have dealt with the respective challenges—both of which are closely identified with revolutionary affairs— this distinction is lost in the notion of revolution, which suggests, above all else, a radical transformation and paradigmatic exchange.

Crisis, furthermore, throws into sharp relief the normal science of chemistry, permitting a profounder inquiry into why and how various early modern chemists

“handle[d] the crisis-provoking problem despite the despair of those who have seen it as the end of an existing paradigm.” Dramatic connotations aside, the “despair experienced by chemists during the two greatest upheavals in the history of early modern chemistry, in being forced to respond to the emergent sets of “crisis-provoking problem[s]”, delineates a significant aspect of my approach.

Although suggestive, “despair” is an abstract category, which needs to be imbued with historical substance. Its structuring cause, the category singled out by the phrase

“crisis-provoking problem,” however, is tangible. It is also useful as a starting point for

22 Kuhn (1962), p. 84

drawing up several conceptual parallels. At a fundamental level, the main charges laid against contemporary chemistry during both revolutions derive from similar metaphysical and epistemological concerns. The respective “crisis-provoking problem[s],” observed in both late seventeenth- as well as late eighteenth-century chemistry, share a fundamental trait: a demand for quantification.23 Given the various backgrounds and contexts, the causes for this increasing concern stemmed from different sources and in response to different emerging questions. Nonetheless, the ideal of a quantified or quantifiable science of chemistry comprised a prominent dimension in the two crises of early modern chemistry.

Quantification and Physicalist Reduction: A “Crisis-Provoking Problem”

Quantification suggests measurements, numbers, computations and accuracy. It may thus be associated with laboratory work, the manipulation of scientific instruments or the variety of experimental practice. Yet in both instances, chemistry and chemists were not faulted for neglecting to measure or for lacking accuracy in their practice. Chemistry was not perceived as lacking experimental quantificational standards. The call for a quantified science of chemistry derived from metaphysical and epistemological considerations. Both Boyle and Lavoisier observed that chemistry was wanting in accuracy yet neither disputed the authenticity or rigor of chemical experiments and practices; neither faulted leading chemists’ procedures and praxis. In general, neither

Boyle nor Lavoisier found chemical experiments unreliable or inaccurate, yet both objected

23 On chemistry and quantification see Guerlac (1961b); Guerlac (1976); Thackray (1970), esp. pp. 199-233; Melhado (1985); Lundgren (1990).

to chemical experimentalism, chemical philosophy, or the rationale behind the chemical experimental programs of their contemporaries: their theoretical considerations and their interpretations of experimental output. As Boyle aptly observed in the Sceptical Chymist:

“There is a big Difference betwixt the being able to make Experiments, and the being able to give a Philosophical Account of them.”24 Boyle’s and especially Lavoisier’s reformations had prominent experimental repercussions, affecting chemical practice in various ways. But in a significant sense, both reformers, much as Kuhn suggested, charged chemistry from the top down, that is, their primary target was chemical theory.

Given the complexity of the interconnection between practice and theory, it is beyond my present scope to distinguish comprehensively between the two realms and their dialectics as pertaining to scientific developments. A prime example of this methodological difficulty is represented by the claim that experimental pursuits are never free of theoretical considerations: they are universally theory-laden. The diametrically opposed claim for the independence of local knowledge within the emergence process, or

‘construction’, of scientific theories is equally problematic. While I leave the clarification of such problems to philosophers of science I wish to acknowledge them and signal their relevance to my work. The difficulty in distinguishing between theory and practice notwithstanding, I suggest that both Boyle’s and Lavoisier’s primary initial concerns were theoretical in nature. More specifically, both judged chemical theory to be unsound while finding experimental chemistry useful.

24 Boyle, The Sceptical Chemist, p. 294 (in Works, vol. II; hereafter abbreviated as SC).

That the respective crises originated in theoretical considerations may be more evident with Boyle, whose critical manifesto, the Sceptical Chymist (1661), advanced a direct critique of matter theories and experimental philosophies. Lavoisier’s rhetoric, on the other hand, expressed his concern with experimental accuracy and instrumental authority. But this should not be confounded with Lavoisier’s experimental agenda. The decline of phlogistic chemistry can hardly be attributed to increased experimental precision and accuracy, as any rudimentary balance would have detected the discrepancies in the gain-and-loss of weight patterns related to combustion and calcination processes, hinted at, for instance, in Kuhn’s “question of weight relations.” Lavoisier employed a multi- pronged strategy in establishing his theoretical agenda, conceptually and linguistically, as part of reinterpreting chemical theory (indeed establishing a new theoretical order) and subsequently practice. I wish, however, to underscore the importance of understanding the multiple contexts through which an intricate notion such as ‘quantification’ may be understood and applied as an explanatory kind or, more specifically, as a unifying principle in a comparison such as the one between the two critical episodes at hand.

In general, Boyle commended contemporary chymists (except for those he designated as “cheats”) for their experimental acuity, practical knowledge and skills, emphasizing their lack of reasoning, a problem he believed could be resolved by recourse to the general principles of the mechanical philosophy, which he generally called the

“Corpuscular Philosophy.”25 Despite Boyle’s qualms concerning the experimental

25 Boyle refrained from associating himself with a particular mechanistic school of thought. He adhered to the claim that, “both the Cartesians and the Atomists explicate the same Phenomena by

philosophies of his contemporaries he did not cast general doubt upon the validity of chymical experiments. He wished to see whether he “could by the help of the Corpuscular

Philosophy… associated with the Chymical Experiments, explicate some particular subjects more intelligibly.”26 Similarly, Lavoisier readily acknowledged the experimental capacities of his greatest rivals (discussed in chapters 2 and 3). Both reformers drew extensively and at times overtly upon the experimental findings of their contemporaries and predecessors.27 The problem was not of experimental or practical inaccuracy but one of theoretical ambiguity and frailty. Boyle was concerned with the obscurity and vagueness of Paracelsian and peripatetic elemental theories whereas Lavoisier considered phlogiston an as an ill-conceived entity. This, again, squares well with Kuhn’s understanding of crisis, which relates to the practical and experimental only indirectly, subsisting primarily at the theoretic-paradigmatic level. Kuhn urged his readers to

“assume that crises are a necessary precondition for the emergence of novel theories,” indicating that, “the novel theory seems a direct response to crisis.”28 In response to these concerns Boyle and Lavoisier proceeded, although in different ways, to promote all- encompassing programs for the quantification of chemical phenomena. By advocating quantification—whether structural-geometric29 or gravimetric—Boyle and Lavoisier hoped

little bodies variously figur’d and mov’d,” adding that he did not wish to “determine [such]… controverted points.” (Boyle, CPE, p. 87) 26 Boyle, Certain Physiological Essays, pp. 87-88 (in Works, vol. II; hereafter abbreviated as CPE). 27 Recent studies have demonstrated Boyle’s inconsistent recognition of intellectual and experimental debts to natural philosophers such as Daniel Sennert, George Starkey, J. B. Van Helmont and others. See Newman (1996); Newman (2006); Newman & Principe (2002). 28 Kuhn (1962), pp. 75, 77; italics added. 29 By structural-geometric (reductive) quantification I mean the general perception of matter (substances, elements, etc) as consisting of minute parcels endowed with extension and some other geometrical, hence primary, qualities such as shape, configuration, size and texture. The various

to achieve, among other things, what they believed was missing in chemistry: unifying standards. They hoped to rid chemistry of what they interpreted as metaphysical (and epistemological) obscurity and ambiguity. Boyle, for instance, insisted upon the intelligibility of mechanical explanations. Lavoisier and his co-authors of the new nomenclature introduced an entirely new linguistic order, to match his newly conceived notions of chemical elements and composition.30 Introducing a new scientific nomenclature is no easy feat and Lavoisier recommended his for its clarity and simplicity, as opposed to the intrinsic ambiguity of phlogistic chemistry. From a rhetorical-critical perspective, analogous to Boyle’s Sceptical Chymist is perhaps Lavoisier’s 1777 memoir titled Réflexions sur le phlogistique, in which he referred to phlogiston as that “vague principle, lacking a rigorous definition, and which is, consequently, adaptable to all explanations… It is a veritable Proteus that changes its form at each instance.”31

In the early 1660s Boyle launched a momentous attack upon contemporary chymical principles: various systems of material or hypostatical elements, mostly based on the Paracelsian Tria Prima (salt, sulfur, mercury), the Aristotelian Four Elements (air, fire, water, earth), or combinations thereof. Arguing that chymical cosmologies based upon

versions of atomism and corpuscularianism qualify as instances of this type of metaphysical quantification, the main difference being that the former presupposes the indivisibility of such material parcels. 30 See Berthollet, Fourcroy, Guyton (1788). 31 The passage reads: “les chimistes ont fait du phlogistique un principe vague qui n’est point rigoureusement défini, et qui, par conséquent, s’adapte à toutes les explications dans lesquelles on veut le faire entrer; tantôt ce principe est pesant, et tantôt il ne l’est pas; tantôt il est le feu libre, tantôt il est le feu combiné avec l’élément terreux ; tantôt il passe à travers les pores des vaisseaux, tantôt ils sont impénétrables pour lui ; il explique à la fois la causticité et la non-causticité, la diaphanéité et l’opacité, les couleurs et l’absence des couleurs. C’est un véritable Protée qui change de forme à chaque instant.” Lavoiser (1862-1893), II, p. 640.

such principles were metaphysically obscure and theoretically precarious, Boyle sought their rejection in favor of mechanistic principles. Boyle suggested the explanation of chymical reactions and phenomena in corpuscular terms, drawing upon distinctly physical features such as the particles’ size, motion, shape, configuration and texture.32 This represented Boyle’s attempt to reconcile the repository of extant chymical experimental data—recipes for the chemical preparation of medicaments, distillation practices, metallurgical procedures as well as alchemically-informed knowledge of metals, salts, solvents and ferments—with the principles of the budding mechanical philosophy. The latter was predicated upon a combination of a particulate theory of matter (revived versions of ancient and medieval atomism) and Cartesian mechanism, according to which all natural phenomena are to be accounted for in terms of matter in motion, matter being endowed with geometrical extension as its sole primary quality.

In the early 1770s Lavoisier embarked on an enterprise that he predicted would lead to a “revolution in physics and chemistry.” Nearly two decades later, his “revolution” reached its climax with his publication of the Elements of Chemistry (1789), the single treatise most closely associated with the Chemical Revolution. Lavoisier reformed the science of chemistry, dislodging the theory of phlogiston and replacing it with his novel theory of combustion, acidity and heat. The most conspicuous general aspect of

Lavoisier’s reformation consisted in the multi-dimensionality and integrity of his system.

32 The distinction between the configuration and texture is a difficult one. However, it seems that for both Locke and for Boyle the terms are not interchangeable. Since this is not crucial to my argument, I do not discuss the nature of the distinction; but I retain it, in line with the historical actors’ usage. For detailed analyses of this subject in the context of Locke’s and Boyle’s philosophy of matter and particulate theories see Alexander (1985); Anstey (2000).

He advanced at once a novel chemical theory—reinterpreting processes such as combustion, calcination and respiration—and a corresponding novel nomenclature. This, in turn, was accompanied by a set of newly devised apparatuses and instrumental practices.

On the whole, the system expressed what has been aptly referred to as Lavoisier’s

“algebraic vision of chemistry.”33 The foremost underlying principle in this system was the conservation of weight, supplemented by an increasing awareness that weight gain meant the addition of matter and that quantitative changes were linked to changes in the properties of bodies. Lavoisier accordingly subjected chemistry to the rule of the balance, advocating a radical quantification of chemical phenomena. Chemical analysis and synthesis were to be determined by observing the changes in the weight of the reactants and products.34

This is a general portrayal of the two major “crisis-provoking problem[s]” found in early modern chemistry. Having outlined the primary challenges posed to chemistry in the early modern period, the notion of “crisis” redirects our attention towards the receiving end—the challenged rather than the challengers, the provoked rather than the provokers— the subjects of the critical episode. Going back, once again, to Kuhn’s conceptual scheme, we can reassess the methodological possibilities afforded by the adoption of the distinction between revolution and crisis, and reflect upon its possible application. It is not simply a matter of looking at the other side of a revolutionary episode, turning our focus from the revolutionaries to their rivals, although in general terms, this study can be said to be first

33 Kim comments about Lavoisier’s “algebraic vision of chemistry and… grammatical understanding of nature.” Kim (2003), p. 380. 34 See Kim (2003), esp. pp. 279-334; Levere (2001), pp. 62-65.

and foremost concerned with the latter while dealing with the former only minimally. Any study, however, looking to establish the nature of early modern chemical thought and practice, by looking at its manifestations during its two most prominent points of crisis— intrinsic parts of two scientific revolutions—would inevitably, almost by definition, end up dealing with the ‘losing’ parties of the respective revolutions.

Both revolution and crisis entail a conflict, suggesting a tension between two poles.

But whereas ‘revolution’ can be said to represent a process, ‘crisis’ is most readily evocative of a state of affairs. Even in the strict Kuhnian sense, a revolution is the resolution of a crisis: a replacement of one paradigm by another is the dynamical- dialectical process by which the resolution of the (pre-revolutionary) “crisis-provoking problem[s]” is negotiated. Let us assume, for the sake of illustration, that A and B represent two paradigms, two rival scientific systems; in the wake of a scientific revolution, B replaces A. Let us further assume that if one were generally interested in how or why B replaced A, one’s inquiry could be said to be concerned with the revolutionary process. If, on the other hand, one were interested in what constituted A, one’s goal would be better realized by looking at the respective pre-revolutionary crisis, to which A and its proponents have been subjected. I neither wish nor intend to brush aside the significance of contextual categories such as rivalry, revolutionaries, assailers, defenders or assailed. Such concepts are useful and widely employed in descriptive analyses of the dynamics underlying revolutionary episodes. Yet I shall substantiate a type of discourse related to these categories only insofar as I approach the subject through the examination of two revolutionary chapters in the history of science. The revolutionary processes, in themselves, serve as passageways into the world of the early modern

chemists, their ways of reasoning, theorizing, arguing and experimenting. Theoretically precluding these dynamics of change while including, indeed revolving around, the element of “crisis-provoking” challenges, the conditions and circumstances of a crisis embody an essential version of “normal science” at its boldest: in the present case, early modern chemistry as the subject of the crises. Employing the simplistic yet instructive dichotomy between winner and loser, it may be said that while ‘revolution’ gives rise to winners, ‘crisis’ is where losers come to the fore. As a human pursuit, science never fails to include drama. Cornered and threatened, facing novel challenges and experiencing “the despair of those who have seen it as the end of an existing paradigm,” the chemists— subjects of the crises and of this study—were forced to redefine their previously taken-for- granted metaphysical commitments and epistemological practices.

THE CHYMICAL VS. THE PHYSICAL: REACTIONS AND ACTIONS IN EARLY MODERN CHEMISTRY

Thematic Outline

At the center of both the seventeenth- and the eighteenth-century endeavors to reform chemistry stood attempts to quantify it and to subject its realm of entities and related phenomena to a restricted and physically informed set of principles. In both cases, chemists—the opposing party, the defenders of the reigning paradigm, the representatives of “normal science” or otherwise those for whom these endeavors represented “crisis- provoking problem[s]”—responded in ways indicating that the physicalist reduction of chemistry, following the attempts at quantification, epitomized their single greatest concern and comprised the ultimate cause of their epistemological and metaphysical

incertitude and “despair.” In primarily exploring the chemists’ reactions and responses to the reforms, the following case studies engage with various aspects arising from the interplay between the ‘chymical’ and the ‘physical’ or, in a more general sense, early modern chemistry and natural philosophy.

Early modern chemists felt threatened by the two major physicalist challenges and reacted accordingly. The interplay between rejection and appropriation plays an important role in identifying the principles underlying the chemists’ reactions, shedding light in turn on their chemical perceptions. The key question of how chemists reacted and dealt with these challenges is better grasped as a series of sub-queries. Bound to defend their once self-evident theoretical and experimental grounds, to what extent did the chemists object to the quantifying-physicalist programs; were they willing to adopt parts of the new discourse or was it integrally rejected; what were the chemists willing to accept and why; and what were they completely unwilling to forgo? As a secondary question we might also wonder about the possibility and degree of theoretical as well as experimental incommensurability.

It is with such questions in mind that we approach the following series of case studies, which exhibit both the variety and the regularity in the nature of the chemists’ reactions, throwing the chymical-versus-physical debates into sharp relief.

The discussions ensuing in both parts (I and II) feature a number of chemists and natural philosophers, chymically- and physically-oriented. In both parts, however, the work of one chemist is more prominent than that of others. The historiographic images of the chemists in question reflect the contrasting states of scholarship in the history of chemistry during the respective periods. Joseph Priestley is a widely known figure both in the immediate context of the Chemical Revolution as well as in the history of science in

general; Samuel Cottereau Duclos, on the other hand, is a virtually unknown seventeenth- century savant, chymical practitioner and founder-member of the Parisian Royal Academy of Sciences.35

Part I focuses on late seventeenth-century chymistry through a scrutiny of the work of Duclos and some of its ramifications within the Parisian Royal Academy of Sciences.

As a critic of Boyle and defender of prominent aspects of traditional chemical philosophy,

Duclos’s work offers an invaluable glimpse at how Boyle’s critique of contemporary chymistry—his critique of elementary theories, experimental philosophies, chymical cosmologies and rejection of substantial qualities and the occult—was received and perceived by a contemporary chymist. Leading chymist of the early French Academy of

Sciences, Duclos may be seen as Boyle’s French counterpart. While rejecting the reductionist mechanization of chymistry, Duclos was forced to defend and expound a modernized version of chemical philosophy, one that would satisfy some of Boyle’s objections yet retain what Duclos deemed as impossible to relinquish without dangerously compromising the status of chymical science. Following various aspects of Duclos’s critique of Boyle, part I explores the boundaries between the traditional chymical philosophy, with its eclectic origins and manifestation, and the new mechanized chymistry advanced as part of the New Science. Duclos’s reactionary reading of Boyle, his chymical views, his interpretation of traditional chymistry, and his travails within an increasingly mechanist-leaning French academic milieu are analyzed and brought together as part of an

35 See background to Part I and Introduction to chapter 2.

attempt to delineate the seventeenth-century chymical style of experimental reasoning

(henceforth SER).

Part II consists of an exploration of late eighteenth-century chemistry within the context of debates and shifts related to the Chemical Revolution.36 Chapter 2 examines the scientific methodology of Priestley, the most influential pneumatic chemist of his generation. In line with the general aims of this study, the chapter offers a corrective antidote to simplistic historiography. Priestley has been traditionally deemed, more than any of his contemporaries, as a reactionary (not only in the scientific context). He has been forcefully associated with the Chemical Revolution, commonly regarded as Lavoisier’s greatest rival and the greatest defender of the phlogistic cause (a problematic claim which I address in chapter 3). Commonly examined against the backdrop of Lavoisier’s systematic reformation, portrayed as a weak theoretician who had stubbornly clung to a defunct phlogistic chemistry, his positive contributions and scientific methodology—his chemical action—have been glossed over. This, however, is also part of what makes Priestley such a suitable candidate—and the analysis of his experimental method comprises such a convenient vehicle—for the elaboration and employment of the category SER.

While chapter 2 is mostly concerned with Priestley’s experimental methodology and with establishing prominent dimensions of the early modern SER, chapter 3 expands the analysis by examining metaphysical aspects underlying leading pneumatic phlogistic views during the Chemical Revolution. Two main strands of phlogistic thought are identified: the relatively short-lived Swedish model, associated with Carl Wilhelm Scheele

36 Chapter 2 builds on Boantza (2007a) and chapter 3 on Boantza (2008).

and Torbern Bergman, and the British model, which originated with Priestley’s findings in the early 1770s. Drawing extensively on Priestley’s phlogistic views, the British model evolved during the 1780s and reached its final version in the phlogistic theory of Richard

Kirwan (present in its full form in his 1787 Essay on Phlogiston and the Constitution of

Acids), constituting the principal chemical phlogistic rival to Lavoisier’s novel theory of combustion and acidity. Chapter 3 uncovers the origins of Kirwan’s theory of phlogiston- as-inflammable-air, demonstrating how it emerged in 1780 as a reaction to Scheele’s

Swedish model while building on Priestley’s phlogistic chemistry. It is subsequently shown that, in contradiction to common historiographic wisdom, Priestley was not phlogiston’s last great defender. Kirwan’s final version of the theory, however, departed from both Priestley’s and Scheele’s distinctly chemical metaphysics by importing physically oriented features originating in quantified research on heat going back to the

Scottish pneumatic tradition of Joseph Black and William Irvine. By employing Adair

Crawford’s consequential research on “animal heat,” Kirwan devised an integrative stand, combining both physical and chymical traits; as such, it showcases important aspects of the interplay between the two research programs, underscoring the way metaphysical commitments and experimental practices influenced each other in the production of physico-chemical knowledge. By devising an integrative outlook, Kirwan managed to narrow the gap of theoretical incommensurability; although this answered some of phlogiston’s difficulties, which have been in fact primarily generated by Lavoisier and his collaborators, phlogistic chemistry became even more exposed to Lavoisier’s charge. In

1792, the year in which Kirwan abandoned the phlogistic cause, phlogistic chemistry was generally considered to have all but disappeared. Contrasting the physical/chymical

dialectics, as related to the topography of the Chemical Revolution, the ‘chymical’ once more serves as a major component of the early modern chemical SER—such as the advanced commitment to pneumatic transmutations and aerial permutations.

Chapter 4 extends the substantiation of the chemical SER by broadening the basis of the case study—following a wider and more diverse range of members of the chemical community, both phlogistonists and anti-phlogistonists—while narrowing down the scope of inquiry, focusing intensely on the nature of the response of the chemists to the physicalist-reductionist challenge before, during and after Lavoisier’s announcement of his most consequential discoveries in the late 1770s and early 1780s. In this sense, chapter 4 is most concerned with a portrayal of the abovementioned “despair”—the loss of a scientific worldview and the metaphysical and practical manifestations of this loss—in face of the “crisis-provoking” set of challenges. The chapter’s narrative keeps close to reactionary expressions of leading late eighteenth-century phlogistic chemists such as

Priestley and Kirwan. Kirwan’s phlogistic summa, his 1789 Essay on Phlogiston and the

Constitution of Acids, embodying a singular dialogue between the phlogistians and the antiphlogistians, is examined in detail, including the contributions by its English translator,

William Nicholson. The chapter reconstructs the set of metaphysical and epistemological assumptions pertinent to phlogistic chemistry by uncovering its opponents’ perceptions of matter, affinity, substances, chemical reactions and processes, substantiating the ontology and experimental philosophy defended under the banner of phlogistic chemistry.

From Reaction to Action: Style of Experimental Reasoning (SER)

The notion of experimental method in the present context is complex and requires elaboration. The role of experimental practice has long been considered as central to the study and understanding of early modern chemistry. This owes, to a large extent, to the traditional origins of ancient and medieval alchemy in metallurgy, mining, natural magic, folk medicine, etc, revolving around praxis and technological knowledge. Such assumptions have given rise to some reductive interpretations of seventeenth- and early eighteenth-century chemistry, which view it as a type of art or craft, consisting in the acquisition and manipulation of technical-practical knowledge and skills that are often secondary to other branches of knowledge.37 A prime example of such an instance is the subordination of chymistry to early modern medicine, as in the case of iatrochemistry

(medical chemistry).38 On such accounts, early modern chemical theory played a limited

37 I discuss the theme of Maker’s Knowledge at some length in chapter 2, relating it to Priestley’s experimental philosophy and to his epistemological predisposition towards the production of chemical effects through experimentation as part of producing scientific effects. 38 It should be noted that in the case of iatrochemistry, the conception of chemistry as a craft and practical art was less influenced by ancient and medieval sources (paradigmatic throughout the Middle Ages and most of the Renaissance, Galenic medicine was theoretically-centered after all). It was rather spurred by the advent of Paracelsianism during the sixteenth- and seventeenth- centuries, with its emphasis on medical empiricism and administration of chemically prepared medicaments. Reactionary and opposed to the established and institutionalized Galenic and Scholastic philosophies, Paracelsian medicine was considered subversive. The clash between the two movements was most prominent in France during the early seventeenth-century, especially between the traditional Parisian faculty of medicine and dissenting academies such the one in Montpellier or Théophraste Renaudot’s Parisian bureau d'adresse et de rencontre. Although it was heavily informed by natural magic, this is not to say that Paracelsian cosmology was purely empirically-oriented, as it consisted of an intricate myriad of abstracted and theoretical notions derived from a mélange of Neo-Platonism, Gnosticism, Hermeticism, Calvinism, Cabbalistic precepts, astrology, etc. On the clash, and especially the ‘antimony wars’ see Debus (1993). For a classical essay on the dissemination of Paracelsian ideas in Europe see Trevor-Roper (1985); for a recent account see Kahn (2007). On Paracelsianism see Debus (2002), esp. pp. 63-204.

role.39 This interpretive strategy is hardly new; it can be traced all the way back to Robert

Boyle’s heavy-handed critique of Paracelsian and peripatetic chemical philosophies, following a tripartite classification of contemporary chymists into “laborants, iatrochemical pharmacists and textbook writers, and Paracelsian systematizers,” as

Principe indicates in his scrutiny of the Sceptical Chymist.40 Boyle praised chymical adepti, who possessed the hermetic-magical knowledge and capabilities, the mastery of which Boyle sought throughout his career. Most intriguing is Boyle’s denigration of the

“laborants” and the medical pharmacists—technical chymists, distillers, herbalists, etc— who were accused of reducing the status of chymistry to a mere practical pursuit. On this account, devoid of much necessary theoretical grandeur, chymical knowledge could not have been an appropriate candidate for joining the ranks of the New Science. Attempting to ennoble chymical discourse by reconciling its repository of experimental data with the budding mechanical philosophy, as part of a theoretical (and quantitative) agenda, Boyle, while retaining his aversion towards metaphysically oriented chemical cosmologies—“the

Paracelsian systematizers”—rejected the pursuit of theoretically-devoid practice.

The application, past or present, of such notions to the study of the history of early modern chemistry has generated historiographical biases. The case of Priestley’s scientific method and experimentalism is a strong case in point, as we shall see in part II. Priestley,

39 See, for instance, Joly (1992), who proposes a radical interpretation according to which the (early modern) alchemical laboratory is the space in which alchemical theory manifests itself. On this view, alchemical practice does not contribute to theory, which is neither confirmed nor invalidated in the laboratory. The role of alchemical practice (in this sense divorced of theory) is to produce effects and reveal (not discover but make manifest) theoretical aspects that have already been established. Joly rejects the existence of alchemical theory-practice dialectics; thus alchemical theory does not progress or evolve by drawing upon practice; the production of alchemical effects is in a sense a theoretical display. 40 Principe (1998), p. 58; on this subject see also Clericuzio (1994).

who was a hesitant theorist and who remained a lifelong supporter of theoretical phlogistic notions, has been commonly misinterpreted as an able practitioner yet raw and unsophisticated theoretician, or, alternatively, as a natural philosopher who took little interest in theorizing, favoring instead the role of scientific educator and popularizer of empirical agendas as part of British Enlightenment scientific culture. Such a view underscores the association between chemical knowledge and the practical and experimental realms. Equally distorting is the identification of chemistry with chemical theory and ideas, as seen in the case of Butterfield’s remark.

The early modern era saw the rise of a new science by way of a series of changes.

Some of these shifts occurred within a broader intellectual transformation that affected the whole of Western philosophy, society, religion and culture, often referred to as the

Intellectual Revolution; other shifts were more particular to scientific discourse. Changes of the latter kind can be broadly classified into two groups: the theoretical move towards a quantification and mathematization of natural phenomena and the practical increasing commitment to systematic observation and experimentation in the study of nature. As the science of matter and material change, chemical knowledge has always been informed by both theory and practice, by philosophy (know-what; know-why) and know-how, by cosmological as well as technological perspectives. This twofold influence can be seen in terms of a symmetry between theory and practice. Such symmetry is arguably more evident in the case of chemistry than in other branches of natural knowledge. I mean this in a general sense, mostly in contrast to other scientific endeavors that lent themselves more readily to quantification; mechanics, optics, astronomy, kinematics, etc., come to

mind in this context, and can be subsequently characterized as exhibiting a lesser degree of such symmetry.41

Historians have labored over the past two or three decades to (re)establish the prominence of practical pursuits in the construction of theoretical ones.42 This kind of scholarship has done much to blur the distinction between theory and practice, holding that the former is much influenced if not fashioned by the latter. Methodologically challenging and mostly polemical, such interpretive strategies have gained substantial scholarly weight, undermining the validity of generalized statements such as the one concerning the prominence of the twofold or symmetrical influence on chemistry. Yet I believe that my claim regarding chemistry’s symmetrical debt to both theory and practice, when considered abstractly, as a comparative measure in relation to other early modern scientific disciplines, remains instructive. I wish further to suggest that early modern chemistry has proved to be a particularly challenging historiographical nut to crack, not least due to this symmetry.

At the same time, early modern chymistry displays a recalcitrant disparity: theory and practice seem often detached from one another. This is most evident in the blend, characteristic of seventeenth-century chymistry, of grand chymico-metaphysical cosmologies alongside technical textbooks comprising recipes and detailed descriptions of laboratory procedures, often brought together in the same treatise. Although sharing some similarities, chymical cosmologies were frequently different in scope and nature,

41 See Dijksterhuis (1961). Sometimes these are referred to as the ‘mathematical’ branches of natural philosophy, as opposed to the non-mathematical ones: medicine, physiology, astrology, etc. The case of early modern chemistry is interesting as it seems to have been characterized as ‘accurate’, possibly partly mathematical science only in the post Chemical Revolution era, prior to which it was most commonly considered by scholars as ‘alchemical’ and hence non-mathematical. 42 A trend also referred to as constructivism, closely associated with the Sociology of Scientific Knowledge. See Golinski (1998).

conveying a sense of idiosyncrasy. This sense has infused the debate over the nature of early modern chymistry and has increased scholarly confusion. Within a balanced interpretation, neither chemical theory nor practice can be dismissed or undermined. Yet demonstrating the connection is often challenging. Again, this seems to be the case with early modern chemistry, especially when compared with either theoretically-centered fields such as mathematics or ancient astronomy or to practically-oriented pursuits, such as instrument making or other any other types of scientific artisanship.43 What is important to note is that in both cases there seems to be a dominant trait, which is adopted as a historiographic platform on which further (challenging or even conflicting) claims can be made concerning the interplay between scientific practice and theory. In the case of early modern chemistry, this type of self-evident orientation is missing. In the attempt to account for the interplay between chemical theory and practice, epistemology and experimental pursuits, I employ the notion of ‘style of reasoning’.44

The series of case studies on which this study builds comprise, within various contexts, a close study of the ways by which chemists fashioned themselves during two of the most consequential moments of conflict seen in early modern chemistry. This strategy, as explained, is not without its difficulties; it requires a deliberate historiographic

43 For an original and insightful account of how scientific epistemology, art and artisanship commingled in the production of knowledge during the Scientific Revolution see Smith (2006). 44 The various uses of ‘style’ in the history and in the philosophy of science, its origins and its relations to other disciplines has been at the center of numerous studies and debates. See, for instance, Daston and Otte (1991), a selection of essays from two conferences: “Styles as a Category in the History and Philosophy of Science” (1987) and “National Styles in Science” (1988). For two excellent discussions on the notion and uses of ‘style’ as a historical category see the first two papers in the collection (Otte, Wessely), pp. 233-278. See also Crombie (1994); Hacking (1992). For a wide-ranging discussion of the concept and uses of ‘style’ in philosophy, literature, fine arts, music and history, see Lang (1979).

approach, the principles of which have been outlined. While some principles are furnished by the form of the study—exploring reactions of chemists to similar types of challenges— others derive from the study’s particular contents and subjects—as depicted, for example, in how both seventeenth- and eighteenth-century challenges to chemistry were closely linked to material quantification, promoting the inquiry into the nature of the dichotomy between the chymical and the physical, which bears out in turn the substantiation of the chymical. Form, however, is only a constituent of a style and we should be careful not to reduce the latter to the former. In his article “Style as a Historical Category,” Otte clarifies this point by explaining the inherent conceptual difficulty. “The category of style,” he notes,

has an objective and a social perspective: It expresses naturally opposing trends insofar as the subject is assumed on the one hand to be an absolute being and on the other to be a socially relativized being. Style becomes an almost paradoxical category… Style itself on the one hand is perceived as a unit that can be closed and detached from its works [artistic, scientific], but on the other hand it designates nothing other than the mere dynamics of development. Style does not exist apart from its works in art or in science.45

“Style does not mean the form,” he concludes, “or the relation between form and content but the meaning of a unity of the two. This unity however is not absolute and static but is a unity of process.”46 I wish to call particular attention to the necessarily dynamical nature of both its “form and content,” coming together through a “unity of process.”

The tools required for carrying out such an exploration are seemingly in place. If we were to compare the present task to an act of excavation (not too remote an analogy)

45 Daston & Otte (1991), pp. 237-238; italics added. 46 Daston & Otte (1991), p. 238; italics added.

we could be said to possess a relatively well-defined map; we know where to excavate and why; we also know what to look for and how to identify it.47 The essential element missing is a receptacle to contain our findings and hold them together, a plane on which to carry out the work of evidencing, by juxtaposing the historical evidence collected. A few circumstances call for the introduction of such a category. A common feature, one may say, of historical work is the presence of a discernible narrative. Common forms include biographical, chronological or thematic narratives; others rely on a plot or a succession of events interlinked by spatial or temporal proximity. The present study, in contrast, draws upon a comparative analysis of theoretical, practical and rhetorical dimensions, gleaned from a series of interconnected case studies. Much of the connection between the corresponding analyses is borne out and created by the methodology employed, one of the major features of which is the deployment of circumstances entailed by the historical crises. The subsequent, deliberate, focus on chemists’ reactions or responses to certain sets of challenges affords particular insights. By privileging these responses, however, we run the risk of undermining and possibly glossing over the peculiar ways in which chemists acted, performed and reasoned in establishing chemical knowledge. More specifically: although I here analyze the reactions of chemists in order to uncover their actions, we still need a category through which to capture what has been uncovered and substantiate it by

47 Mentioning excavating, Foucault’s archaeology comes to mind. On this point, however, I agree with Hacking’s remark that ‘style of reasoning’ should not be identified with Foucaultian ‘episteme’ but that “this concept, of a style of reason, when added to the ‘concepts, strategies’ and so forth that preoccupy Foucault in the Archaeology of Knowledge, would do much of the work demanded by Foucault’s completely opaque notion of the ‘archive.’” Hacking (1983), p. 460.

bearing out the interrelationship between the types of ‘action’ within the context of the production of chemical knowledge.

For this purpose I employ “style of reasoning,” which I take from I. Hacking, who paraphrases A. C. Crombie’s “styles of scientific thinking.”48 Crombie defined “scientific style” only loosely and broadly as a category meant to identify “certain regularities in the experience of nature which became its object of inquiry.” Following this, according to

Crombie, “the interactions between style and subject matter then generated the appropriate methods of inquiry” so that “within each style diverse but cognate subject-matters were brought together under a common form of argument.”49 Hacking drew on Crombie’s

‘style’ to suggest “a new analytical tool that can be used by historians and by philosophers for different purposes.” Like Hacking, I prefer “(scientific) ‘reasoning’ rather than

Crombie’s ‘thinking’… partly because thinking is too much in the head.” Hacking, however, rebuked even “reasoning” for not sufficiently invoking “the manipulative hand and the attentive eye.”50

Crombie’s notion of style has a different, non-analytical, origin: his monumental

Styles of Scientific Thinking in the European Tradition belongs among the ranks of comparative cultural anthropology and longue durée intellectual history. A

48 See the title of Crombie (1994). His six Styles of Thinking are: (1) Postulation and the Ancient Search for Principles and Methods; (2) The Experimental Argument; (3) Hypothetical Modelling; (4) Taxonomy; (5) Probabilistic and Statistical Analysis; (6) Historical Derivation: the Genetic Method. 49 Crombie (1994), p. xi. For an earlier general articulation of ‘styles’ of scientific thinking in the Western tradition see Crombie (1988). 50 Hacking (1992), pp. 1-4. Hacking mentions also various uses of ‘style’ by Stephen Weinberg and Noam Chomsky to describe the “Galilean style of reasoning in physics” (drawing its roots from Edmund Husserl), Ludwig Fleck’s use of the term, Michel Foucault’s ‘episteme’ and Nicholas Jardine’s ‘questions’. For earlier reflections on this theme see Hacking (1983).

methodological intimation illustrates his conception of style as also related, implicitly, to objectivity and truth: “we must look for the questions they [historical actors] were asking within their mental horizons and for whatever it was that made certain types of question cogent and certain types of answer satisfying – and others not. We put our questions to our historical sources with this intention.”51 In the historical characterization of styles

Crombie identified three major commitments. First, the outlines of a style as “conditioned by language.” Second, “the conception of science and of the organization of scientific inquiry, argument and explanation.” Third, delineations “of what is desirable and possible, in view of evaluations of the nature, purpose and circumstance of human life.”52 To use a well-known literary distinction, whereas Hacking tells us what styles consist of, Crombie mostly shows—by juxtaposing fragments of “historical sources”—how different collective modes of grasping and manipulating nature emerged within different intellectual and cultural spheres across the history of the Western tradition (from Antiquity to the

Renaissance).

I am interested in style as a category that is less over-arching in space, time and metaphysical implications than both abovementioned versions. My present use of style does, however, build on dimensions found in both Hacking and Crombie. From Hacking I take the emphasis on “reasoning.” It is where he indicates that his “study is as a continuation of Kant’s project of explaining how objectivity is possible” that I part company with him and his employment of the notion as a category that ultimately “settled

51 Crombie (1994), p. 5, italics added. 52 Crombie (1994), pp. 56-62.

what it is to be objective.”53 In applying style my emphasis is on how different experimental and theoretical aspects were interwoven and brought together to generate chemical knowledge rather than on what were the conditions and commitments that established this knowledge as objective. In this respect, my use of style highlights the relationship between “the manipulative hand and the attentive eye,” in Hacking’s words.

Accordingly, I suggest a revision of this analytical tool to “style of experimental reasoning” (SER), which reminds us of chemistry’s debt to both experiment and reason within the context of a scientific style.

I favor SER over methodology or experimentalism because it suggests an additional—personalizing—usage. Hacking mentioned the distinction between “a

‘generalizing’ and a ‘personalizing’ use of the word ‘style’,” pointing out that, “there is the

Balzacian style and there is Balzac’s style.”54 As the singularity of Duclos’s or Priestley’s experimental activities is demonstrated, I utilize Duclos’s style rather than a possible

Duclosian style, and Priestley’s style rather Priestleyan style. The personalizing usage, moreover, squares well with the non-conformist makeup of both chemical practitioners in question. While the former has been crudely underrepresented, the latter has been mostly misrepresented in the history of chemistry and science in general.55 I show how singular aspects of both Duclos’s and Priestley’s SER, setting them apart from their contemporaries, have recurrently infused the historiographic debate regarding their scientific merits. Duclos’s case has been further influenced by triumphalist Anglo-centric

53 Hacking (1992), p. 4. 54 Hacking (1992), p. 2. 55 For an instructive and succinct summary, sketching “the dynamic ‘tensions’ in Priestley’s life and thought” see McEvoy (2000), p. 76.

historiography, consistently associating chymistry with alchemical pseudo-science or pitting British empiricism and observational practices against French rationalism and dogmatism.

Yet the way I employ SER is meant to transcend the personalizing usage. Having introduced its general characteristics, SER evolves in close relation to the historical analyses provided. Further defining it, a-priori, would go against its very meaning and purpose. The notion of SER is employed and reemployed, and cast and recast throughout the study, in order to capture the dynamics of the production of early modern chemical knowledge. Applied to various subjects, it wavers between its “personalizing” dimension, as in Priestley’s or Duclos’s SER and its “generalizing” sense, as in a possible ‘eighteenth- century chemical-pneumatic SER’ or the ‘seventeenth-century chemico-physical SER’.

Exploring the relation between style and knowledge, Otte explains that style,

helps the work of art to be better perceived as such, but style alone does not produce a work of art. To subordinate the work of art completely to style appears empty, formal, abstract, and not really viable. The work of art is not contained by its style; each complements the other, and it is this complementarity, understood as simultaneous relation and difference, that first creates an evolutionary dynamic. This can also serve as an instructive model for understanding other cognitive or historical processes.56

My overall purpose in using style can be illustrated by substituting, in this passage, Otte’s

“work of art” with early modern chemistry or early modern chemical knowledge. The rest must be gleaned from the ensuing analysis, in which SER complements the early modern chemical objects and subjects of action and inquiry, hopefully helping early modern chemisty “to be better perceived as such.”

56 Daston & Otte (1991), p. 239.

PART I: CHYMISTRY AND THE SCIENTIFIC REVOLUTION

CHAPTER 1

CHEMICAL PHILOSOPHY AND BOYLE’S PHILOSOPHICAL CHEMISTRY: DUCLOS READS BOYLE

BACKGROUND

Samuel C. Duclos and Chymistry at the Early Académie

On October 1685, the Amsterdam journal Nouvelles de la République des Lettres featured the following announcement:

The [French Royal] Academy of Sciences has recently lost one of its members by the death of M. du Clos. He was a physician aged 87 who lived in the house containing the Bibliothèque du roi. He disliked attending the sick, and he preferred to give his time to study, to chemical experiments, and to research on the Philosopher's Stone. This is how M. Clément, who lives in the same house as proposé à la garde of the King's Library under M. Thevenot, came to make the following declaration on behalf of this good man.

Following this short note, a “copy of a manuscript by M. Clément containing the declaration that M. du Clos made shortly before his death concerning the Philosopher’s

Stone” appeared:

The 20 August 1685, Monsieur du Clos, physician, being on his sick bed but sound in mind and judgment, I approached him to ask if he had anything to say concerning his writings; he told me that if I was spoken to about them, he begged me to bear witness that he had no complete work except a treatise on salts and mixtures that he had put in the hands of M. de la Chapelle; that he had meant for a long time to publish this treatise; that M. Colbert and a substantial proportion of the Academy had approved it, but that M. du Hamel, being always opposed to it on account of certain opinions that he could not accept, he had not been able to obtain permission to get it printed, a fact that obliged him to give one part to Elsevier who was at the time in Paris, & who printed it in Amsterdam. Regarding the other writings,

he stated that he had burnt them five or six months before. I let him know the wrong he had done in depriving his friends of the knowledge to be drawn from so many fine observations; but he told me that they were only formless fragments and nothing more; that, seeing that he was in no state to analyze them nor to put them in order & no one after him being capable of doing it in the same spirit, he preferred to put them in the fire. That, moreover, M. Friquet, his nephew who is a painter and professor of anatomy in the Royal Academy of Painting, tolerably successful in his field, he feared that if after his death he found these writings, most of which were observations and experiments on the transmutation of metals, that that would give him the opportunity to take up research that would divert him from his profession and cause him to waste his time and resources so uselessly. Upon which, I took the opportunity to put it to him that it would undoubtedly be advantageous to the general public, and even to the service of the King, if a man as able as he is, and who had employed the best part of his life to research on natural causes, particularly those concerning transmutation of metals and on that called the Great Work, should make known what he thought of the usefulness or uselessness of such research & that the acknowledgement he would make about it in the state he was in would have great weight in keeping those who engage too readily in this unfortunate passion for the art of the bellows; he replied with admirable presence and strength of mind that he was ready to swear that all the research he had done had served only to confirm him in his present way of thinking, that there was nothing more futile nor more useless than holding out the hope of being able to arrive at the transformation of metals, for that required them to change their essences, which was not possible. […] I asked M. du Clos if, for the satisfaction of his friends, he would not be happy for me to write under his direction what he wished me to say on the subject, he told me that he was not in a fit state at that moment and that if he felt his mind clear enough, he would willingly do it. But his strength has diminished ever since without my being able to find the [right] time to extract from him a coherent statement. And since he has always singled me out among those whom he honored with his friendship and trust during the last 15 years that we have lived in the same house, I have believed it necessary to offer to his memory this testimony, making known what I heard of his feelings more or less in the words in which he explained them. The esteem and reputation he acquired amongst the worthy men who knew him will perhaps ensure that they will not be distressed to see what he thought about a question to which he had applied so many experiments and so much fine knowledge without other success than that of having

recognized its futility, at a time when nothing obliged him to conceal his true beliefs.57

This is an intriguing document; its subject, “Monsieur du Clos,” is even more so. Samuel

Cottereau Duclos (1598-1685) was among the first founding members of the French Royal

Academy of Science and part of a group of eminent natural philosophers personally selected by Jean-Baptiste Colbert (1619-1683), who was minister of finance from 1665 to

1683 under Louis XIV, and the Academy’s protector from its establishment in 1666 until his death in 1683.58 At the time of his election, as one of two chymists, along with Claude

Bourdelin,59 Duclos was already 68 years old. This election suggests that he was held in high professional esteem as a chymical practitioner. He ran a laboratory in Paris prior to joining the Academy, and Nicaise Lefebvre, later appointed as court chymist and apothecary to king Charles II and author of a popular chymical textbook, was among

Duclos’s students.60

57 Nouvelles de la République des Lettres, October 1685, pp. 1139-1143. For this English translation and also for the original text in French and other details on the early Academy and on Duclos see Meynell (2002). 58 For background on the early academy see Saunders (1980); Mallon (1983). Published studies discussing the Academy during the seventeenth-century include: Maindron (1888); Brown (1934); Bertrand (1969); Hahn (1971); Taton (1966); Hirschfield (1981); Stroup (1990); Sturdy (1995). 59 On Bourdelin see Dorveaux (1929); Partington (1961-70), III, p. 13. 60 Stroup (1990), p. 18-19; Nicaise Lefebvre wrote in his Compleat Body of Chymistry: “at Paris, I had the happinesse of liberty to converse with M. du Clos Dr. of Physick, who did me the favour to correct my defaults, and lead me as by the hand of his judgment and experience, through all that which I have undertaken in my endeavours to advance the diginity of Pharmacy, which now lies, bending toward its ruine, if it be not upheld by its true Arches and Pillars, those faithful, learned, experience’d and curious Physitians. This Excellent and rare Physitian denyed me none of those lights, or illustrations, that are necessary for the well-doing of those that addict themselves to the legitimate preparation of Pharmacy; so that I am indebted to Him for the well-being I have acquired in my Profession.” Lefebvre (1664), Epistle, p. iii. On Lefebvre see Partington (1961- 1970), III, pp. 17-24; Metzger (1969), pp. 62-82; Debus (1991), pp. 125-130.

Duclos emerges for the historian at the end of 1666, almost ex nihilo, with the inauguration of the Academy and his appointment as senior academician.61 One of the greatest puzzles surrounding Duclos’s life and career has been expressed by Sturdy who observed that it has been “exceedingly difficult” to “adduce documentary evidence relating to the biography” of Duclos. Yet “this savant,” he noted, “so elusive to the present-day scholar in one respect, nevertheless was among the most active members of the Académie des Sciences during its early and formative period.” The chronicles of the early academy—and its minutes, the procès-verbaux for the period 1666-69 in particular62—bear witness to an exceptionally high level of activity and influence on Duclos’s part, who is mentioned more than any other academician.63 As we shall see, contrary to his deathbed proclamation that he had “burnt them [his writings] five or six months before,” several of

Duclos’s works survive in manuscript form; when considered together with the numerous memoirs found in the Academy’s minutes, this constitutes a substantial corpus of unpublished works, consisting mostly of experimental reports.

Nevertheless, the challenge of reconstructing his pre-academic career remains considerable, not least because four Protestant physicians named Samuel du Clos are known to have flourished at the same time.64 Among the founding members of the

61 Duclos is discussed briefly in Metzger (1969), pp. 266-272. He is mentioned in Partington (1961-70), III, pp. 11-13; Debus (1991), p. 151; Principe (1998), p. 40; all authors erroneously state his date of death as 1715. Duclos is recently receiving increasing scholarly attention by Stroup (2002); Clericuzio (2000), pp. 178-180; Kim (2003), esp. pp. 48-52; Holmes (2003); Jacob (2006), esp. pp. 52-65; Boantza (2007b). 62 The procès-verbaux of the early Academy—the minutes in which all the memoirs delivered during the weekly meetings have been recorded—survived only partially: nearly four year, 1670- 74, are missing. 63 Sturdy (1995), pp. 107-108. 64 Todericiu (1974).

Academy were seven ‘mathematicians’, responsible for research into geometry and astronomy, and seven ‘philosophers’, in charge of physics, chemistry, anatomy, medicine and botany. During the early period, Duclos dominated the research agenda of the

‘philosophical’ group, presenting memoirs on topics that were key in both institutional as well as philosophical contexts, such as research into the principles of mixts, botany and plant analysis (as part of the ambitious project on the Histoire des Plantes), mineral water analysis, etc.

Sturdy’s institutional and genealogical survey of the Academy and its academicians suggests a preference for savants in their 40s and in their 60s; the former were regarded as the Academy’s future intellectual spearhead while the latter were recruited for their scientific distinction, experience and prestige.65 In chemistry, this prototype was followed closely. The younger Claude Bourdelin, practicing apothecary and adept experimenter, was hired to help Duclos equip, build up and manage the intended laboratories, and to help him to develop the program for chymical analysis.66 Bourdelin, however, never ascended beyond the status of a reliable distiller. While the senior Duclos determined the chymical research agenda and conducted chymical lecture-demonstrations for the scientific assembly, Bourdelin zealously carried out vast numbers of systematic distillations, mostly of plant matter. Duclos invoked matter theories as a crucial subject to be discussed by academicians and shared with them his concern over the chemical validity of fire analysis.

65 Sturdy (1995), parts 2 and 3. 66 Chemical analysis was a central part of the early Academy’s research and part of leading projects such as the examination of French mineral waters and spas as well as the overly ambitious ‘natural history of plants’ project. See Stroup (1990); for a study dedicated to chemistry at the early Academy see Stubbs (1939) but also Holmes (2003); Holmes (2004).

Drawing upon Paracelsian and especially Helmontian perceptions, Duclos professed his belief in solution analysis as the ultimate chemical tool. The application of a universal solvent (alkahest) held the promise of transcending the received products of distillation— the Paracelsian Tria prima, the Aristotelian four elements or other various combinations thereof, which consisted mostly of pentads employed in operative fashions—towards an authentic chemical resolution of mixts into their true principles (elements).

Unlike other academicians, following his appointment, Duclos conducted his entire research within the Academy, in part due to his special relationship to its laboratory, which he designed and administered and in which he also resided for some time.67 His only published works, the Observations on the Mineral Waters of France and a

Dissertation on the Principles of Natural Mixts, were the outcome of work carried out within the institution.68 The essay on mineral waters was commissioned by the Crown and published in Paris in 1675. The dissertation on natural mixts, however, advancing a vitalistic cosmology inspired by Neo-Platonic and Paracelsian philosophies, was denied publication by the increasingly mechanistically leaning Academy of the 1670s and was subsequently printed in Amsterdam in 1680, where censorship was minimal; it was published by Elzevier, Van Helmont’s publisher. The Dissertation is mentioned in his deathbed declaration and referred to as the “treatise on salts and mixtures.” Duclos pointed a blaming finger at Duhamel (the academy’s secretary) as the actual censor, “being always

67 Sturdy (1995), pp. 107-109. 68 Duclos (1675); Duclos (1680).

opposed to it on account of certain opinions that he could not accept.”69 Two things are worth pointing out in this context. First, Duclos’s “treatise on salts and mixtures,” as he referred to it, most probably corresponds to his initial plan, in which the Dissertation comprised only one part of a larger work, including a treatise on salts. Given his dwindling academic status during the 1670s and 1680s, Duclos was obliged “to give one part to Elsevier who was at the time in Paris, & who printed it in Amsterdam.” The second part, the “treatise on salts,” is found in manuscript entitled Dissertations sur les sel, contenüe en plusieurs letters escrites à un physicien de l’Académie royale des Sciences par un autre physicien de la mesme Académie, en l’an 1677.70

In the unpublished manuscript, Duclos is referred to as a “physicien” of the

Academy. The full title of the published half is Dissertation sur les principes des mixtes naturels, fait en l’an 1677, par le Sr Du Clos, Conseiller et Médecin ordinaire du Roy, & l’un des Physiciens de l’Académie Royale des Sciences. This is in accord with Clément’s designation of Duclos as a “physician” but it also suggests his function as a Royal physician. Between 1666 and 1680, when the Dissertation was published, Duclos held his appointment as Royal Academician, which suggests that he may have been a court

69 MS. fr. 1333. Duclos, Dissertations physiques … faites en l'an 1677 and Remarques sur les Essais physiologiques de Boyle, July 1688, from f. 238. The former is the original version of Duclos's Dissertations physiques sur les principes des mixtes naturels, as submitted to the Academy in his application to publish the book; the negative report of four academicians— Blondel, Du Hamel, Perrault, and Mariotte—appears on fols. 42v–44r. 70 MS. fr. 12309 (MF. 15775). This is an epistolary manuscript consisting of 29 unsigned letters, arranged according to four main themes “Du sel en général,” “Des sels primitifs nitreux,” “of several particular salts,” and “Du sel commun resoult & circulé.” For details on this treatise see Franckowiak (2003), pp. 137-149.

physician sometime before 1666.71 In any case, it seems that at least during his career as academician (the last nineteen years of his life), Duclos dedicated himself exclusively to chymical studies, as his longtime neighbor Clément remarked: Duclos “disliked attending the sick, and he preferred to give his time to study, to chemical experiments, and to research on the Philosopher's Stone.” Yet here another intriguing paradox arises. Duclos, in Clément words, “had employed the best part of his life to research on natural causes, particularly those concerning transmutation of metals and on that called the Great Work.”

Such a lifelong pursuit of chymistry and alchemy on Duclos’s part is conceivable, especially in light of his memoirs, which bear witness to his vast knowledge on the subject and chymical skills.

Why, then, should Duclos decide to abjure his alchemical beliefs on his deathbed, intimating that, “there was nothing more futile or more useless than holding out the hope of being able to arrive at the transformation of metals”? Duclos denied the possibility of metallic transmutation and warned against the pursuit for the “Philosopher's Stone.” Two explanations are provided, one internal, the other external. The first concerned scientific knowledge, reflecting perhaps Duclos’s ultimate disillusionment in finding that metals cannot “change their essences.” The other was unrelated to matters of scientific knowledge per se and seems to have been part of a moral concern of Duclos, endorsed by

Clément; namely, to discourage “those who engage too readily in this unfortunate passion for the art of the bellows.” Duclos, however, had someone specific in mind: “M. Friquet,

71 The author could not find corroborating evidence for this. Duclos’s name does not appear in the registries listing physicians and apothecaries recruited to the Royal Court, dating back to the early 1640s. It possible that Duclos held an appointment at one of the Ducal courts outside Paris.

his nephew… painter and professor of anatomy at the Royal Academy of Painting,” whose career Duclos sought to protect during the last months of his life. The revocation of the

Edict of Nantes almost coincided with Duclos’s death. The overall intellectual climate seems to have been adverse. Marquise de Louvois, the protector of the Academy after

Colbert (from 1683 to 1691) was minister of war and mastermind of the dragoons

(dragonnades), instituted in 1681 in order to intimidate Huguenot families into either leaving France or converting to Catholicism. Indeed, most members of the chemico- medical community in seventeenth-century France were Protestant. In light of these political and social changes, Duclos’s abjuration of alchemy seems to have been more political than sincere.

“Precise Speculations” and “Sensible Operations”

Nearly half a century after Duclos’s death in 1685, the perpetual secretary to the

Academy, Bernard de Fontenelle, remarked that Boyle

had ventured to explain all chemical phenomena according to the corpuscular philosophy, that is, by the sole movement and configuration of small particles. Mr. du Clos… being possibly more chemically-minded, did not find it necessary, nor possible, to reduce this science [of chemistry] to such clear principles such as shapes and movements and had subsequently subscribed to a misleading obscurity.72

72 Fontenelle (1733), I, p. 79: Boyle “avoit entrepris de rendre raison de tous les Phénomènes Chimiques par la Philosophie corpusculaire, c’est-a-dire, par les seuls mouvemens & les seuls configurations des petits corps. M. du Clos, grand Chimiste, aussi-bien que M. Boyle, mais ayant peut-être un tour d’esprit plus chimiste, ne trouvoit pas qu’il fut nécessaire, ni meme possible, de réduire cette Science a des principes aussi clairs que les figures & les mouvemens, & il s’accommodoit sans peine d’une certaine obscurité spécieuse.”

A devout Cartesian, Fontenelle offered a demarcation—suggestive of his ardent beliefs in mechanical agendas as applied to natural philosophy—between chemistry and physics.

“Chemistry,” he argued,

resolves bodies by sensible operations into certain gross and palpable principles such as salts, sulphurs, etc. Physics, however, by power of its precise speculations, acts upon these principles, like chemistry does on bodies, by resolving them into yet finer and simpler principles, that is, the motion and infinite configurations of small particles. Herein, then, lies the principal difference between physics and chemistry; akin to the difference between Mr. Boyle and Mr. Duclos.73

He then surmised that contemporaneous chemistry was plagued by confusion and obscurity whereas natural philosophy, which he and his contemporaries called physics, exemplified a neat clarity. The spirit of Fontenelle’s eulogy has cast an enduring spell upon the historiography of early modern chemistry. While Boyle has been repeatedly praised for liberating chymistry from its pseudo-scientific roots, delivering it from mysterious obscurity to scientific light, Duclos’s chymistry has been largely overlooked. Thanks to recent scholarship, we now have a richer portrait of Boyle’s chymical and theological pursuits, yet we still know little about his reception on the Continent. Duclos was a critic of the mechanical reduction of chymistry, a vitalistic corpuscularian, and one of the most influential members of the early Academy; a contextualization of his work accordingly sheds light on the intersection where operational and theoretical dimensions converged to produce chymical knowledge.

73 Fontenelle (1733), I, pp. 80-81: “La Chimie par des opérations visibles résout les corps en certains principes grossiers & palpables, sels, souffres, &c. Mais la Phisique par des spéculations délicates agit sur ces principes, comme la Chimie a fait sur les corps, elle les résout eux-mêmes en d’autres principes encore plus simples, en petits corps mus & figures d’une infinité de façons : voila la principale différence de la Phisique & de la Chimie, & presque la même qui etoit entre M. Boyle, & M. du Clos.”

Given his mechanistic proclivities and considered in retrospect, Fontenelle’s evaluation is neither surprising nor singular. In fact, it squares well with numerous other contemporary depictions of Boyle, praising his association with “physics,” the

“corpuscular philosophy” and clarity, as opposed to a “chemistry” of “principles,” hopelessly plagued by “a misleading obscurity.” Nor is it all that different from the first modern assessments of Boyle’s science.74 My interest in Fontenelle’s remarks, as a starting point, is due to their specific origin and context. The remarks comprise his depiction—in the first volume of the Histoire de l’Académie Royale des Sciences, covering the Academy’s activities during its first two decades—of Duclos’s critical assessment of

Boyle’s Certain Physiological Essays, conducted during the winter of 1668-69.75

Frederic L. Holmes, in a posthumously published article, argued aptly that,

“Duclos’s discussion of natural mixts exemplifies the mélange of thought styles juxtaposed in the discourse of seventeenth century chemistry.”76 Holmes’s reference to “mélange” is illustrative, particularly due to its somewhat passive overtones, which might suggest that

Duclos was a point of convergence rather than, for instance, the hub of a single heated scientific controversy. This approach, moreover, is profitable for both inquiring into

Duclos’s chymical SER as well as for establishing it in a wider context, as an exemplar of

74 The view of Boyle as mechanical philosopher and ‘physicist’ goes back to his contemporaries and immediate successors (Leibniz, Peter Shaw, etc); similar depictions appeared in the eighteenth- century. Venel, for instance, “in his article ‘Chymie’ for the Encyelopédie, in which he aimed at discriminating between chemistry and physics, complained that Boyle ‘est trop exactement physicien corpusculaire-mechaniciéne, ou physicien proprement dit’ and suggested placing him among the physicists rather than among the chemists.” Clericuzio (1990), p. 562. Hall (1958), the first twentieth-century influential historical study of Boyle’s science, echoes similar sentiments. See also Cook (2001); Kim (1991). 75 Duclos used the 1667 Latin edition Tentamina Quædam Physiologica, a translation of the 1661 English edition. 76 Holmes (2003), p. 46.

seventeenth-century chymical discourse and SER. The historiographical focus on scientific controversies, to be sure, has become a commonplace in the history and philosophy of science, reaching a climax in the works of social constructivists. In a celebrated instance of this genre, Shapin and Schaffer’s Leviathan and the Air-Pump, the authors wondered, “How can the historian play the stranger to experimental culture, a culture we are said to share with a setting in the past…?” By way of an answer the authors suggested the examination of scientific disputes, explaining that the “advantage afforded by studying controversy is that historical actors frequently… attempt to deconstruct the taken-for-granted quality of their antagonists’ preferred beliefs and practices.”77 Duclos’s

1668-69 critique of Boyle’s Physiological Essays lines up well with Shapin and Schaffer’s maxim; Duclos indeed exposed and “deconstruct[ed] [some of Boyle’s] taken-for-granted qualities… preferred beliefs and practices.” Fontenelle, too, observed that Duclos’s examination of Boyle’s book consisted of a very profound discussion.78

Shortly after his appointment, Duclos, at the behest of fellow academicians undertook to examine Boyle’s chemical work. During the winter of 1668-69, from

September to February, he led the traditional Saturday meetings of the “philosophical group” with lecture-demonstrations, scrutinizing Boyle’s five Physiological Essays, written in Oxford during the late 1650s and first published in 1661. Boyle’s Essays are complex and intriguing works, concerning two main themes, as their respective and mostly self-explanatory titles suggest: Two Essays Concerning the Unsuccessfulness of

Experiments and two additional essays referred to as Some Specimens of an Attempt to

77 Shapin & Schaffer (1985), pp. 6-7. 78 Fontenelle (1733), I, p. 81.

Make Chymical Experiments Useful to Illustrate the Notions of the Corpuscular

Philosophy. A fifth, a Proemial Essay, was appended to serve as a lengthy introduction.

Duclos chose to survey the Essays as they would serve as a foil to criticize Boyle’s mechanistic agenda, as well as to promote Duclos’s own chymical cosmology. On a general level, the choice of Duclos was conceived as a vehicle for presenting the academy with a confrontation between the chemical and the mechanical, or, in Fontenelle’s words, to touch upon “the principal difference between physics and chemistry.”

Duclos’s critique, prima facie, highlights experimental practices and skill, challenging issues concerning the contingency of chemical matter and manner, and debating the applicability of mechanical explanations to chemistry. The lecture- demonstrations attest to Duclos’s empirical commitment, laboratory expertise, and intimate knowledge of substances, reactions and chemical processes. The memoirs further reveal his extensive knowledge of the written chymical corpus—and his systematic appeal to textual authorship—as the text overflows with references to numerous authorities and authors, from Roger Bacon, Paracelsus and Van Helmont to the less well-known

Christophe Glaser, Otto Tachenius, and Deiconti. Insofar as skill and erudition are concerned, Duclos emerges as superior to his English counterpart. This virtual debate, conducted in Latin and French, encompasses an exceptionally wide array of experimental details. Chosen excerpts from Boyle’s work (the 1667 Latin edition Tentamina chemica) were cited and illustrated to the members of the assembly, then evaluated, and either commented upon or refuted experimentally. Following this pattern, by invoking both “the manipulative hand and the attentive eye,” Duclos’s lecture-demonstrations (and prime instances of his SER) transcended textual and experimental analysis to bear upon broad

metaphysical agendas concerning chymical authorship, method and language, as well as matter theories and the relation between chymistry and the New Philosophy.

Although the scrutiny of the Physiological Essays was Duclos’s most systematic and comprehensive treatment of Boyle, it is not the only one. During 1666-1669, as the most active and vocal among founder-academicians, Duclos referred to Boyle many times.

While awaiting the establishment of the chymical laboratory, Duclos took the opportunity to discuss chymical issues and spark debates over matter theories, the nature of chymical analysis and corresponding elemental perceptions, chymical experimentation and textual authorship, as well as the application of the corpuscular philosophy to chymical theory and practice. Even a cursory inspection of the multitude of chymical subjects analyzed by

Duclos, mostly by way of lecture-demonstrations, reveals a close kinship to the issues that preoccupied Boyle, especially during the 1660s, his most active and fruitful period of chymical inquiry. Having immersed himself in natural philosophy and chymical studies during the late 1640s and 1650s, in the following decade Boyle published the influential

Sceptical Chymist (1661) and other works such as Certain Physiological Essays (1661),

Usefulness of Natural Philosophy (pt. 1; 1663), The Origin of Forms and Qualities (1666), etc. In what follows, Duclos’s references to the Origin of Forms and to the Physiological

Essays are most prominent. Throughout his memoirs, Duclos referred explicitly to the

“Chymista Scepticus”79 only once, pointing out Boyle’s favorable reference to Van

Helmont’s alkahest. There is little doubt, however, that many of the chymical subjects

79 Académie Royale des Sciences, Procès-Verbal de séance, tome 4: 144v (hereafter abbreviated as AdS, PV); reference to the 1662 Latin edition of the Sceptical Chymist, the Chymista scepticus, vel, Dubia et paradoxa chymico-physica circa spagyricorum principia

Duclos invoked in front of the assembly, especially during 1666-68, were closely related to the critique of traditional chymistry, as exemplified in the Sceptical Chymist. Since this was Boyle’s foremost critique of contemporary chymistry—his most explicit “crisis- provoking” treatise—I discuss it at some length.

THE CRISIS OF CHYMICAL PRINCIPLES

Recent scholarship has pointed to the previously overlooked complex character of

The Sceptical Chymist, a multi-layered and polemical manifesto that announced and created a crisis in seventeenth-century chymistry.80 Although the precise categorization of the subjects of Boyle’s skepticism has many ramifications, bearing as much upon Boyle as upon the identity of the seventeenth-century chymical community, two groups of chymical practitioners stand out as clear targets: the Paracelsian systematizers and the iatrochemical textbook writers. The former, exemplified by the work of, e.g., Joseph Duchesne

(Quercetanus), are condemned for advancing grand cosmologies on frail experimental bases; the latter, represented by, e.g., Jean Beguin, are reprimanded for reducing chymistry to mere practice, manual operations and pharmaceutics.81 Both groups have their origins in the Paracelsian movement. At the core of Boyle’s critique lay his claim for a discrepancy between chymical theory and practice: these two camps of knowledge have gained a disadvantageous independence. This undesired effect is most vividly apparent in the mismatch between chymical analysis and elemental theories. Boyle honed in on this

80 Principe (1998), Clericuzio (1994). 81 On Beguin see Metzger (1969), pp. 35-51; Partington (1961-70), III, pp. 2-4; Clericuzio (2006). On Duchesne see Kahn (2007), passim; Hirai (2001).

weakness to present a lengthy critique of fire analysis (the ‘art’ of distillation) and its corresponding products, regarded by Paracelsians, spagyrists and vulgar chymists as the elementary constituents of bodies.

While for Fontenelle chymistry was both “confused” and “shrouded in mystery,” we find Boyle complaining about the chymists’ “obscure, ambiguous, and almost

Aenigmatical Way of expressing what they pretend to Teach,” a practice and discourse arising from “their Dark and Smoakie Laboratories,” awaiting to be exposed and “brought into the open light.”82 A problem of still graver import, however, can be gleaned from

Fontenelle’s (unintentional) equivocal use of “principles”: to denote Boyle’s adoption of

“clear principles [such] as shapes and movements” of minute particles on the one hand, and to refer to Duclos’s advocacy of dubious “principles such as salts, sulfurs, etc” on the other. On this account, whereas Boyle subscribed to the clear ‘principles’ of the mechanico-corpuscular philosophy, Duclos is associated with a matter theory predicated upon the Paracelsian Tria Prima, the three principles-elements of salt, sulfur and mercury.

In both cases, the primary allusion is to a particular matter theory closely associated with a research program, the physical and the chymical, respectively.

In the prefatory passages to the Sceptical Chymist Boyle declared his

“unsatisfyedness not only with the Peripatetick, but with the Chymical Doctrine of the

Primitive Ingredients of Bodies.”83 The former represents matter theories and chymical explanations based on the Four Aristotelian Elements (earth, water, fire, air), which Boyle faulted for being rationally rather then empirically deduced. Since the “Assertors of the

82 Boyle, SC, pp. 209-211 83 Boyle, SC, p. 215

four Elements value Reason so highly,” they have considered it “much more high and

Philosophical to discover things a priore, then a posteriore. And therefore the

Peripateticks have not been very sollicitous to gather Experiments to prove their

Doctrines.” Nevertheless, Boyle allowed that the peripatetic doctrine was, to a certain degree, “clear and intelligible to the Understanding as obvious to the sense”; it also originated with Aristotle who drew upon “Theories of former Philosophers, which are now with great applause revived.”84 In discussing the advocates of the “Chymical Doctrine,” however, Boyle employed vitriolic language, depicting “Paracelsus and some few other sooty Empiricks” as philosophers who,

having their eyes darken’d, and their Brains troubl’d with the smoke of their own Furnaces, began to rail at the Peripatetick Doctrine, which they were too illiterate to understand, and to tell the credulous World, that they could see but three Ingredients in mixt Bodies; which to gain themselves the repute of Inventors, they endeavoured to disguise by calling them, instead of Earth, and Fire, and Vapour, Salt, Sulphur, and Mercury, to which they gave the canting title of Hypostatical Principles.85

Clearly, the “principles” of “mixed Bodies” comprise one of Boyle’s major targets as he rejected the peripatetic Four Elements, the chymical Tria Prima as well as any combination thereof, consisting mostly of operative elemental pentads. In fact, Boyle denied the possibility of a definite number of elements, conforming to chymical analysis.

What Boyle was really after, however, were not the experiments adduced by chymists but their interpretations of these experiments: “It is one thing to be able to help Nature to

84 Boyle, SC, pp. 221-222 85 Boyle, SC, p. 223

produce things, and another thing to Understand well the Nature of the things produc’d.”86

More specifically, he suggested that, “There is a big Difference betwixt the being able to make Experiments, and the being able to give a Philosophical Account of them.”87

The tenor of Boyle’s discussion in the Sceptical Chymist is mostly critical; he was critical of various contemporary matter theories, chymical cosmologies and analytical chymical perceptions, yet his own suggestions and remedies were only hinted at hesitatingly and sporadically.88 Boyle attacked the spagyrists for not providing causal explanations; for performing experiments, which they interpreted while being prejudiced by theory; for identifying the Tria Prima because it was what they had expected to see. In fact, Boyle was not so much against the experimental practices of the vulgar chemists but rather against the “Suppositions which Chymists as well as Periateticks, without proving, take for granted; and upon which Depends the Validity of the Inference they draw from their Experiments.”89 The core of Boyle’s critique can be gleaned from the various descriptions he had employed in communicating his reservations concerning the state of contemporary chymistry. Chymical discourse, he stated, is “Obscure, Ambiguous and

Aenigmatical”; chymists fail to write “intelligibly enough” and exhibit an “over great- reservedness”; “without proving” their arguments, the “validity” of their interpretations is questionable; given the “unreasonable liberty they give themselves of playing with Names at pleasure,” chymical entities lack fixed referents; finally, Boyle admonished chymists for

86 Boyle, SC, p. 278. For an excellent treatment of Boyle’s experimental philosophy and its origins see Sargent (1995). 87 Boyle, SC, p. 294. 88 See Franckowiak (2008), who suggests that in this context Boyle was interested in discrediting rather than correcting. (p. 4) 89 Boyle, SC, p. 277.

not having “Clear and Distinct Notions” concerning elements, for being “Un-

Philosophical.”90

Striving for clarity, intelligibility, open discourse, causal proof, “validity” and

“Clear and Distinct Notions,” in works following the Sceptical Chymist, Boyle advanced a reformulation of chymical discourse along what he aptly designated as “physico-chymical” lines.91 The traditional claim that Boyle revolutionized seventeenth-century chymistry by identifying it with “the spirit of physics,” in the sense conveyed by Fontenelle—an all- encompassing reductive mechanization of contemporary chymistry—has been aptly challenged and qualified.92 Yet even in the opening lines of the Sceptical Chymist we find

Boyle highlighting the link between chymical experiments, mechanical perceptions and causality:

though I am a great Lover of Chymical Experiments… I distinguish these from their Notions about the Causes of things, and their manner of Generation. And for ought I can hitherto discern, there are a thousand Phaenommena in Nature… which will scarcely be clearly & satisfactorily made out by them that confine themselves to deduce things from Salt, Sulphur and Mercury, and the other Notions peculiar to the Chymists, without taking much more Notice than they are wont to do, of the Motions and Figures, of the small Parts of Matter.93

This passage represents, in an abstract sense, the outline of Boyle’s program— encompassing his vision for a solution to the difficulties aforementioned—upon which

90 Boyle, SC, pp. 209, 211, 213, 277, 291-92. 91 The phrase is taken from the title of Boyle’s ‘Essay on Niter’: A Physico-Chymical Essay… Redintegration of Salt-Petre in Boyle, CPE, p. 93. 92 Most forcefully suggested by Hall (1958) and challenged by, e.g., Clericuzio (1990); Chalmers (1993). See also Kim (1991). 93 Boyle, SC, p. 208; italics added.

Boyle would elaborate in various works and particularly in the Physiological Essays, which drew the close attention of Duclos and the Academy.

“OUT OF THE STRONG CAME SOMETHING SWEET”

Duclos’s first substantial discussion of Boyle came in a memoir entitled

“Observations on certain salts, effectively sweet, drawn from highly acrid materials.”94

The memoir, “proposed to the assembly” on 26 Mars 1667, was delivered the following week. The opening statement reads: “The first of these observations is by Mr. Boyle who, like Samson, has presented an enigma.”95 The reference is traced to the fourth experiment occurring in the second section of the “historical part” of Boyles’s then recently-published

Origin of Forms and Qualities (1666).96

Duclos’s allusion to Samson is instructive. Having chosen Delilah for wife, from among the philistines at Timnah, Samson threw a weeklong wedding feast. To the celebrating philistines he said, “let me now put a riddle to you; if you can tell me what it is, within the seven days of the feast, and find it out, then I will give you thirty linen garments and thirty festal garments; but if you cannot tell me what it is, then you shall give me thirty linen garments and thirty festal garments.” Samson’s riddle—“Out of the eater came something to eat. Out of the strong came something sweet”—originated in an incident in

94 Duclos mentions Boyle twice beforehand: with respect to his experiments with the air-pump and in a letter, reproduced by Duclos, of his former student and colleague, Nicaise Lefebvre, Fellow of the Royal Society since 1663 and chymist and apothecary in the court of Charles II. 95 AdS, PV, 1: 93-94. 96 Published about a year prior to Duclos memoir: March-April 1666. Boyle, On the Origin of Forms and Qualities, p. xxviii (in Works, vol. V; hereafter abbreviated as OFQ).

which Samson was attacked by a lion. Samson tore the lion apart piece by piece with his bare hands and then went on his way. Some time later, he came back by the place were he had slain the lion and observed that inside the carcass, a swarm of bees had made a hive and that inside the hive was a honeycomb full of honey. Accordingly, the phrases “out of the eater” and “out of the strong” refer to the lion while the phrases “something to eat” and something sweet,” refer to the honey. Failing to come up with the answer, the philistines threatened Delilah, who enticed her husband and ultimately divulged the answer: “What is sweeter than honey? What is stronger than a lion?” An enraged Samson replied, accusing the philistines, “If you had not plowed with my heifer, you would not have found out my riddle,” the “heifer” representing Delilah.97

Duclos employed the fable as a metaphor to point to Boyle’s condescending view of the chymists, for if Boyle is identified with Samson, the chymists are but lowly philistines. Duclos in effect mocked Boyle for not abiding by his own standards. Having condemned the chymists so fiercely for writing “enigmatically” and for exhibiting an “over great-reservedness”— which he claimed was detrimental to scientific and philosophical discourse—Boyle presented, according to Duclos, an “enigma”; unlike Samson, he did not even “promise a reward.”98 This cynical undertone, as we shall see, is a prominent and recurrent theme in Duclos’s critical reading of Boyle and in the rhetoric of his SER, often suggesting that Boyle presented various excuses and justifications in order to cover up for

97 Judges 14: 12-18 (Darby Bible Translation); the “heifer” represents Delilah. 98 AdS, PV, 1: 93-4.

his lack of knowledge or proficiency. Addressing Pyrophilus,99 Boyle excused himself for discoursing “upon the Phaenomena of an Experiment, which I do not teach you to make… since I cannot as yet… plainly disclose to you what I must now conceal.”100 Duclos was hardly impressed with Boyle’s excuses: to him, this double standard was unacceptable.

Duclos reformulated Samson’s riddle—“Out of the strong came something sweet”—and recast it as a chymical query—“what is the sweetness that proceeds from acrimony”— relating it directly to Boyle’s “enigma.” Presenting the issue before the assembly, Duclos wrote:

Mr. Boyle, having extracted a sweet salt out of some very acrid materials, refuses to elaborate. He only describes a few [of its] singular qualities, in virtue of which he had designated it as anomalous. After having excused himself for acting against his own custom and inclination, he proposes to uncover a curious experiment, which he is committed to keep secret and not divulge, neither the materials [involved], nor the method. He describes some properties of an extraordinary salt that he has first produced following his own plan and then remade, while adding something, following the advice of a knowledgeable and well traveled chymist, who recommended it to him as a highly special and precious salt.101

These words set the stage for the rest of Duclos’s memoir concerning “Observations on certain salts… drawn from highly acrid materials,” which is dedicated to an exhaustive inquiry into the origins and nature of this “precious salt.” The account consists, among other things, of an exposition of numerous weaknesses on Boyle’s part, as perceived from a distinctly chymical standpoint, as opposed to “Physico-Chymical” middle grounds.

99 This was Boyle’s pseudonym for Mr. Richard Jones, son of the Lord Viscount Ranelagh. Boyle, Works, II, p. 6. 100 Boyle, OFQ, p. 407. 101 AdS, PV, 1: 94; Duclos depiction consists of an accurate rendition of Boyle’s words (Boyle, OFQ, p. 407).

“And though I found,” Boyle reported, “the way of making this Salt so nice and intricate a thing, that if I would, I could scarce easily describe it, so as to enable most men to practice it.” Duclos referred to this statement and proceeded to render a detailed list of various other properties related to the salt, as depicted by Boyle. For instance, according to Boyle all the ingredients composing the salt were “far more salt then Brine, or more sowr than the strongest Vinegar,” yet the salt itself was “rather sweet.” Boyle declared that this was the “onely instance” he had ever come across in which salts “compose a substance really sweet.”102 In his closing remark Duclos indicated that, “these, then, are the properties of the sweet salt that Mr. Boyle drew from certain salty, acidic and acrid materials, which he refuses to otherwise specify, allowing us the liberty to brood over [the issue].”103

Duclos drew up unmistakable parallels between Boyle’s mysterious salt and a similar substance and extraction reported by the German pharmacist Johan Schroeder, in his Quercetanus redivivus, hoc est, Ars medica dogmatico-hermetica (1638). The experiment in question, Duclos claimed, is attributed to no other than Quercetanus, the

Latinized namesake of Duchesne (d. 1609; also known as Sieur de la Violette), commonly identified as a Paracelsian systematizer par excellence (in particular due to the metaphysical chymical cosmology expounded in his Le grand miroir du monde, 1587).104

Exhibiting his supreme knowledge of the chymical corpus, Duclos set out to solve

Boyle’s “enigma.” Duclos explained (and quoted) that Duchesne, much as Boyle,

102 Boyle, OFQ, pp. 407-408; Duclos’s corresponding depiction found in AdS, PV, 1: 94-95. 103 AdS, PV, 1: 97. 104 Debus (1991), pp. 51-59.

described the production of a sweet salt out of salty, acidic and acrid substances. What follows is Duclos’s rendition of Duchesne’s account, relayed in extenso as it provides an invaluable passageway into various dimensions of Duclos’s chymical SER and his corresponding interpretation of Boyle. “It is the case, [Duchesne] claimed,”

that we engage in the research of the admirable effects produced by sea salt, which we employ for the seasoning of all our meats, and which is so vital to human life that it cannot be ignored. If we commence [our discussion] with the crystals of the marine salt, which are obtained from such an acrid and salty materials, there is little doubt that the illiterate [i.e. unlettered, uninformed, uninitiated] will mock us, claiming that this is not possible. And indeed, if we judge our proposition by such reasoning, it will seem ridiculous. But we do not submit [our proposition] to such judgment. It is of the True Philosophers that we write here, those that posses vast knowledge and know the truth. It is because of them, however, that we cannot be understood but by those initiated in this art, that know the terms, and who are imbued with the True Philosophy.

Duchesne’s account of the production of the salt follows:

In order to succeed in the preparation of these sweet crystals of marine salt, having dissolved the marine salt in its proper and natural menstruum, then filtering and coagulating the solution, according to the rules of the art, and repeating this until the salt becomes very pure and clear, one should take six ‘livres’ and pour them onto a vitriolic and mellifluous solvent, consisting of vegetal and animal matters; the quantity should enable a good fermentation; after the necessary digestion has been achieved, [the solvent] acts as a vehicle, elevating with greater ease the phlegmatic, sulphureous and vitriolic spirits, the sweet and the acidic, which are strongly attached to the salt. This extraction of the different spirits should be conducted in an earth retort, which can sustain the fire and yield it in degrees in a most careful and accurate manner, for this is the principal thing in this whole affair. This is why the operation should be performed by an artist who knows well how to manipulate the furnace and regulate the fire, which must be such that the retort does not turn too red but acquires only a faint shade of red, so that the salt inside does not melt; for the spirits to be given off properly, this equal degree of fire must be maintained for eight days, and therefore the recipient should be watched carefully, [and it should be ensured] that it is strongly secured at the joints, and that nothing escapes… [what follows is a condensation] into a highly acidic liquor, after which an earth sublimates from the neck of the retort into the recipient… the recipient should then be

vigorously shaken, to get the sublimate well mixed with the liquor, and all [the recipient’s] contents should be emptied into a glass alembic, separating the three principles… having attached the alembic to its recipient, the insipid phlegm should be distilled on a very gentle fire using a vapor bath; the alembic should then be placed in a cold place, where very distinct, sweet tasting crystals will form.

Besides being sweet, according to Duchesne, the salt is possessed of several remarkable characteristics. First, it is capable of dissolving gold “radically” and of “heightening” its vital virtues, which suggests that Duchesne had probably associated the salt with the practice of metallic transmutations. Secondly, should withered and dry flowers be drenched in a solution of this salt in aqua fortis (nitric acid), they will recover their previous color and vivacity. Thirdly, Duchesne reported his preparation of a “universal medicine” out of this salt and having applied it successfully.105 Boyle made do with

105 AdS, PV, 1: 97-99: “Il est juste, dit il, que nous nous appliquions aussy a la recherche des effets admirable que peut produire le sel de la mer, du quel nous nous servions pour donner l’assaisonnement a toutes nos viandes, et qui est si nécessaire a la vie humaine qu’on ne s’en peut pas bien passer. Si nous commençons par les cristaux du sel marin qui se tirent d’un matière si acre et si salée, il ny a point de doute que les ignorans se mocqueront de nous, ne jugeant pas que cela se puisse faire. Et de vray si nous remettons cela au raisonnement de ces tens la nostre proposition passera pour ridicule. Mais nous ne la soumettons par a leur jugement. C’est aux vray philosophes que nous escrivons cecy, comme a ceux qui en sçauront mieux connoistre la vérité. C’est en leur faveur néanmoins que nous ne puissions estre entendus que de ceux qui sont initiez en cet art, qui en sçavent les termes, et qui sont imbus de la vraye philosophie… Pour réussir en la préparation de ces cristaux doux de sel marin, ayant fait dissoudre le sel marin en son menstrue propre et naturel, puis filtré et coagulé la solution, selon les regles de l’art, et réitéré tant de fois que ce sel soit devenu très pur, et très clair, il en faut prendre six livres, et y surverser d’un certain dissolvant vitriolé et melliflué fait d’un matière végétale, et animale, y mettant de cette liqueur, en telle quantité qu’elle suffise pour procurer une meilleure fermentation, afin qu’apres en avoir fair une digestion convenable, il serve de véhicule pour faire élever plus facilement les esprits phlegmatiques, les sulphurez et les vitriolez les doux et ceux qui sont acides, lequels sont tout fortement liez au corps du sel, cette extraction de ces différents esprits se doit faire dans des cornues de terre qui soustiennent le feu comme font celles de Beauvais, donnant le feu par degrez avec soin et addresse ; car on cecy consiste le principal de l’affaire, et pour ce il faut y commettre un artiste qui l’entende bien il faut aussy que le fourneau de réverbère soit propre a y pouvoir bien régler le feu, qui doit estre tel que la cornue ne rougisse pas trop, mais quelle prenne seulement couleur de rouge obscur, et tanné, a ce que le sel qui est dedans ne fonde pas ; car les esprits ne

mysterious allusions, stating that the salt is “exceedingly noble” and that “besides some of the things I had been told [by the anonymous traveler] it would perform, I could do divers other things with it,” but since some related phenomena are “not so proper for this place,

[they] are reserv’d for another.”106 Such remarks suggest that Boyle too was aware of the salt’s powerful capacities and that he at least associated it with some kind of heightened activity, the precise nature of which remains concealed.

Before returning to Duclos’s discussion of Duchesne, a few contextualizing remarks concerning Boyle’s part are in place. Unlike the numerous experimental instances found in his earlier Physiological Essays, in The Origin of Forms and Qualities, Boyle declared that he “deliver[s] Experiments, not so much as parts of Natural History, [but] as instances to confirm the Hypotheses, and Discourses they are annexed to.” And it is the

“Particularian Philosophy” that Boyle sought to “Confirm and Illustrate” by presenting various chymical phenomena. He urged corpuscularians to “endeavour to illustrate and promote the New Philosophy, by addicting themselves to Experiments, and perusing the

Books of Chymists,” which would help “make the Corpuscularian Philosophy, assisted by

Chymistry, preferred to that which has so long obtained in the Schools.”107

To this end, in The Origin of Forms, Boyle set out to present, in a partly Baconian vein, a multitude of “Notes and Experiments concerning the Productions and Changes of

Particular Qualities.” Wishing to advance the “Principles of the Corpuscularian

s’en pourroient bien dégager, ce degré de feu doit estre continué également durant huict jours, et cependant il faut bien predre garde au récipient, qu’il soit bien lutté aux jointures, et qu’il n’en sorte bien… elles se condenseront en liqueur très acides, apres que tout les esprits sont passez, il se sublime au col de la cornue en en celuy de récipient.” 106 Boyle, OFQ, p. 407. 107 Boyle, OFQ, pp. 392-393.

Philosophy,” Boyle undertook to “subjoyn some such Natural Phaenomena, as either induce me to take up such Notions, or which I was directed to find out by the Notions I had imbrac’d.” This is the backdrop against which the report concerning the “anomalous salt” should be read. Not all the experimental observations expounded in The Origin of Forms are explicitly interpreted within a corpuscularian framework. Some, like the ones pertaining to our salt, consist of an exposition of various “Productions and Changes of [its]

Particular Qualities.” Nonetheless, Boyle clearly trusted that “Nature”—whether

“Master’d by Art” or left “to disclose her Self freely”—will not fail to “attest the Truth of our Doctrine.”108

In Duclos’s final opinion, Boyle’s sweet anomalous salt bears such great resemblance to Duchesne’s sweet crystals, that in all probability “they are the same thing,” an identification that is further evinced by the nature of “the substances from which the salt is extracted, its qualities and its virtues.”109 Duclos’s first comment, following the lengthy description of Duchesne’s procedure,110 touched precisely upon the interpretation of the salt’s “Particular Qualities.” Boyle’s primary reason for discussing the salt arose from the stark contrast between the taste of the components and that of the composed:

several Ingredients, that compos’d this Salt, were all of them such, as Vulgar Chymists must according to their Principles, look upon as purely Saline, and were each of them far more salt then Brine, or more sowr then the strongest Vinegar, or more strongly tasted then either of those two Liquors; yet the Compound, made up of onely such Bodies, is so far from being eminently salt, or sowr, or insipid, that the Stranger being ask’d, what

108 Boyle, OFQ, p. 381. 109 AdS, PV, 1: 100. 110 Duclos also drew parallels between Boyle’s account and a report taken from Hartman’s notes on Croll, which I shall not discuss here. The reference is probably to the 1635 Oswaldi Crolli Basilica chymica, pluribus selectis & secretissimis propria manuali experientia approbatis descriptionibus, & usu remediorum chymicorum selectissimorum aucta a Ioan Hartmanno.

Tast it had, would not scruple to judge it rather sweet, than of any other Tast.111

Boyle presupposed that any “Vulgar” explanation of this phenomenon would entail recourse to substantial qualities (possibly their multiplication), in order to represent the three distinct tastes mentioned, corresponding to “several Ingredients” or constituents of the salt, the identity of which Boyle refused to disclose.112 Following Duchesne’s procedure—and obviously his own experience—for Duclos, little mystery was involved.

The “three different tastes,” he explained, “mark three kinds of different materials which correspond closely to three substances which compete materially in the production of the crystals of the sweet salt.” Duclos identified these as the marine salt (salty), honey vinegar

(sour)113 and the acid (spirit) that is distilled and extracted from the two (acrid; in effect,

Boyle’s “more strongly tasted then either of those two Liquors.”). Boyle wrote of a salt that is “rather sweet, than of any other Tast,” a “really sweet” salt. Duclos maintained:

the anomalous salt of Mr. Boyle is sweet, [it is possessed] of a real sweetness, and he [Boyle] is astonished as to how this sweetness can proceed from such salty materials. The crystals of Mr. Du Chesne are possessed of a real and manifest sweetness.

Herein, then, to paraphrase Fontenelle, lies one of the principal differences between Mr.

Boyle and Mr. Duclos, who added:

If this astonishes a learned and great chymist such as Mr. Boyle, Mr. Du Chesne is well justified in his fear of the judgment of the ignorant[s] and of

111 Boyle, OFQ, p. 407. 112 On the problem of qualities and ‘substantial forms’ see Henry (1986), Anstey (2000), Hutchison (1982), Alexander (1985), Emerton (1984). 113 Duclos used the term “vinaigre fait de miel.” This ‘honey vinegar’ refers to what Duchesne described as the “mellifluous solvent, consisting of vegetal and animal matters.”

being ridiculed for proposing the extraction of sweet crystals from marine salt.114

We are now warranted in asking: who is the ‘vulgar’ chymist and who is the

‘philosophical’ one? But first, let us review Duclos’s accomplishment before examining it further. Prima facie, Duclos had introduced before the assembly a chymical conundrum, which he then proceeded to resolve. Both the context, however, and the text suggest much more. Duclos’s reading of Boyle is intricate and multi-layered; we can learn as much from the critique leveled against Boyle as we can from Duclos’s presentation. Ultimately, it comprised a testimony concerning the ways by which a seventeenth-century chymical philosopher read an aspiring philosophical chymist.115 More specifically, it was a

‘traditional’ chymical practitioner’s reactionary statement in face of a novel, self- proclaimed revisionist chymical program.

Throughout the memoir, Duclos displayed an authoritative hand in both his critical and his constructive inquiry. Duclos deconstructed Boyle’s account while employing it as a vehicle both to expose Boyle—and what Boyle stood for—and to advance his own agenda. While Boyle was interested in refashioning chymistry according to new “physico- chymical” principles, in the spirit of the New Science (especially in the context of the mechanical philosophy), Duclos was intent upon reforming chymistry by clarifying, possibly recasting, its status vis-à-vis its complex traditional origins. These were two

114 AdS, PV, 1: 103: “Si un homme docte et grand chimiste, comme est Monsr Boële, s’estonne de cela, le sr du Chesne a eu grande raison de craindre le jugement des ignorants, et de passer pour ridicule en la proposition qu’il fait de l’extraction des cristaux doux du sel marin.” 115 I take this wording from Kim (2001), p. 379. Kim contrasts ‘chemical philosophy’ with ‘philosophical chemistry’ to highlight the difference between traditional early modern chemistry (the former) and Boyle’s program, striving to ‘philosophize’ chemistry. The latter term should be read with the meaning of philosopher as natural philosopher.

radically different endeavors, represented by two different strategies to transform chymistry into a “modern” pursuit, as Duclos referred to it numerous times, setting it apart yet not severing it from ancient, magical, alchemical or Hermetical trends.116 Duclos’ SER suggests his high metaphysical and epistemological standards, for he was ‘defending’ traditional chymistry in a post-Boylean fashion. Aware of Boyle’s critique, and while reacting against it, Duclos faulted Boyle’s lack of chymical knowledge while insisting upon aspects of traditional chymistry that, in his view, could not be glossed over without compromising essential and distinct aspects of chymical knowledge. This is a prominent characteristic of Duclos’s SER, one that we shall encounter repeatedly; in this respect

Duclos can be said to be a post-Sceptical Chymist chymist.117 Throughout his career,

Boyle displayed a tortured and ambivalent relationship with chymistry’s roots, tradition and past. Given Boyle’s inconsistent acknowledgment of his sources, it is hardly surprising that we have no clear evidence of his knowledge or recognition of Duclos.118

Duclos’s abundant references to Boyle,119 accentuated by his lengthy and systematic scrutiny of the Physiological Essays, however, indicate that Duclos perceived Boyle’s work as a major turning point.

Although Duclos made it clear that Boyle’s display of secrecy is unacceptable, this claim in itself does not comprise the core of his criticism. Duclos used the analogy between Samson versus the philistines, on the one hand, and Boyle versus the vulgar

116 Duclos repeatedly distinguished between the “philosophes hermetiques” and “chimistes vulgaire,” setting them apart from “les chymiste[s] modernes.” AdS, PV, 1: 6-7. 117 I take this wording from Frankowiack (2007). 118 See Newman (2006) for Boyle’s plagiarism of Daniel Sennert. 119 To be sure, Duclos refers equally to Paracelsus and Van Helmont; however, Boyle is treated particularly and predominantly in a critical fashion.

chymists on the other, as a springboard into his discussion of the nature of chymical knowledge. He questioned at once Boyle’s mastership of the written chymical corpus and the validity of his arguments while showcasing his shortcomings as a practitioner.

Establishing beyond experimental doubt the fact that Boyle’s “anomalous salt” is the same as Duchesne’s (conceivably described well over half a century earlier), Duclos concluded that since Boyle admitted that this is the “onley [such] instance” he “hitherto met with of

Salts,” it follows that “he either has not read Duchesne or that his anomalous salt is not different from the abovementioned sweet crystals of marine salt.”120 In other words, Boyle is either unfamiliar with Duchesne—in which case the level of his erudition is questionable, leading him to makes false claims for originality—or, possibly worse, Boyle failed to acknowledge his sources; so much for Boyle’s advocacy of “perusing the Books of Chymists.” Recent explorations of Boyle’s intellectual and practical debts to alchemy and contemporary chymistry have emphasized his restricted recognition of sources, suggestive of his ambiguous relation to traditional chymistry. 121

Duclos’s cynicism reached a climax in his description of “a learned and great chymist such as Mr. Boyle,” who “is astonished as to how this sweetness can proceed from such salty materials.” Granted that Boyle’s astonishment was at least partly rhetorical— hinting at the possibility of explaining the transformation of qualities in corpuscular terms—Duclos was well justified in casting doubt upon Boyle’s understanding of the issues at stake. Significantly, Duclos did not question Boyle’s experiments per se but his chymical interpretations, on which account Boyle may be seen as a fine experimenter but a

120 Boyle, OFQ, p. 408; AdS, PV, 1: 103. 121 See, for instance, Newman (1996); Principe (1998); Newman & Principe (2002), esp. pp. 6-34.

poor chymical philosopher. Boyle further remarked that “Another thing considerable in our Anoumalous Salt is, That though its Odour be not either strong or offensive… yet if it be a little urg’d with heat,” it will give off a strong and offensive smell; this squares well with the reports of “some, that have been us’d to the powerful stink of Aqua fortis, distill’d

Urine, and even spirit of Sal Armoniack its self.” Yet, Boyle added, “when these Fumes settle again into a Salt, their Odour will again prove mild and inoffensive, if not pleasant.”122 Duclos conceded that,

Mr. Du Chesne has not mentioned this with respect to the salt crystals; but those which have seen and smelled, as I did, can assure [themselves] that these salt crystals, when cold, do not have a disagreeable smell; but those [smells] rendered by the fire are not a bit pleasant.123

Recalling Carneades’s words in the Sceptical Chymist, it is not about “being able to make

Experiments,” but about “being able to give a Philosophical Account of them,” that concerned Duclos in this case.

Duclos’s “account” revolved around Duchesne’s procedure, with which he was personally acquainted. Towards the end of the memoir Duclos mentioned Boyle’s complaint that since the procedure is “so elusive and so encumbering,” he (Boyle) found it difficult to describe and teach.124 Yet Duclos’s memoir comprised, in itself, a refutation of this statement. However, what Duclos found of primary significance was that in his work,

122 Boyle, OFQ, p. 408. 123 AdS, PV, 1: 101: “Le Sr du Chesne n’apoint remarque cela en ses cristaux de sel ; mais ceux qui les ont veus et flairez comme j’ay fait, peuvent asseurer que ces cristaux doux de sel estant froids, n’ont point d’odeur désagréable ; mais que celles qu’ils rendent au feu n’est gueres plaisante.” italics added. 124 Boyle wrote: “I found the way of making this Salt so nice and intricate a thing, if I would, I could scarce easily describe it, so as to enable most men to practice it.” (Boyle, OFQ, p. 407).

Mr. Du Chesne has made it very clear in the procedure he had described… [that it] requires much industry and accuracy, for which a highly skilled and conscientious artist [practitioner] is needed, high quality vessels and a furnace in which the fire can be well adjusted.125

Duchesne was equally explicit: the distillation is the most important part of the whole procedure. The fire should be manipulated and its “degrees” controlled “in a most careful and accurate manner, for this is the principal thing in the whole affair.” The operation would succeed only when performed by “an artist who knows well how to manipulate the furnace and control the fire,” its degree and intensity, which should be accurately sustained for “eight days.” Duchesne prescribed that the vessel employed should “not become too red but [should] acquire only a faint shade of red”, while Duclos claimed to have “seen and smelled” these “crystals of Mr. Du Chesne [which] are possessed of a real and manifest sweetness.” The procedure, then, was both attainable and describable. Its success, however, depended much on the proficiency and aptitude of the artist, in which context, the fire, the furnace, and the skill of the distiller were of prime significance.

The “philistine” chymist has resolved Samson’s riddle. For Duclos there was no riddle to begin with, nothing to be “astonished” about; hence the implicit rejection of

Boyle’s underlying message, presenting the case of the “Anoumalous Salt” as a momentous experimental instance, evincing the requirement of “Chymists to learn and relish the Notions of the Corpuscular Philosophy.” The alternative was depicted by Boyle in the preface to the section discussed:

125 AdS, PV, 1: 103: “Le Sr du Chesne a bien fait voir en la procédure qu’il a descripte… qu’il y faut beaucoup d’industrie, et bien de l’exactitude, et désire pour cela un artiste bien soigneux et bien expert, de bons vaisseaux et un fourneau bien propre a reigler le feu.” italics added.

To ascribe all Phaenomena, that seem any thing Difficult, (for abundance are not thought so, that are so,) to substantial Forms, and, but nominally understood, Qualities, is so general and easie a way of resolving Difficulties, that it allows Naturalists, without Disparagement, to be very Careless and Lazy… where as the Cultivators of the Particularian Philosophy, being obliged by the nature of their Hypothesis, and their way of Reasoning, to give the particular Accounts and Explications of particular Phaenomena of Nature, are also obliged, not only to know the general Laws and Course of Nature, but to enquire into the particular Structure of the Bodies they are conversant with, as that wherein, for the most part, their Power of acting, and Disposition to be acted on, does depend.126

Fontenelle held that Duclos had “subscribed to a misleading obscurity,” not unlike the one

Boyle railed against in this passage. Yet if we follow the discussion closely, Duclos hardly seems to be “Careless and Lazy” or as prescribing easy “way[s] of resolving Difficulties.”

Nor was he ill-acquainted with the “Laws and Course of Nature.” If anything, Duclos— the chymist who had “seen and smelled,” who stressed the “real and manifest,” who highlighted the skill and industry of the operator, and whose discussion revolves around the “furnace” and “substances which compete materially”—seems to have been at odds with “Hypothesis.” Duchesne certainly drew upon the “three principles” and Fontenelle chided Duclos for his recourse to “gross and palpable principles such as salts, sulfurs, etc.”

These references to the Tria Prima need to be set against the background of yet another significant dimension of Duclos’s SER: his chymical operative epistemology, to which we now turn.

126 Boyle, OFQ, p. 393.

DUCLOS’S PRINCIPLES

On the last day of 1666, Duclos delivered the first communication of the

‘philosophical group’ in a memoir bearing the title of Projet d’exercitations physiques.

Early on he made a statement much in line with the spirit of Boyle’s Sceptical Chymist:

“those that have proceeded inaccurately in their search for the principles of natural mixts, by way of chymical analysis, have adopted mercury, salt and sulfur, as principles and primary constituents.” The Tria Prima, Duclos asserted, cannot be considered as elementary. “A most accurate resolution” would demonstrate that these three principles could be further resolved (decomposed): sulfur into water, salt and earth; mercury into salt and phlegm; salt into phlegmatic water and earth. The Tria Prima, therefore, “being neither simple nor primary, cannot be principles.” However, whereas Boyle associated

‘modernity’ with the likes of Bacon, Descartes, and Gassendi, Duclos was inspired by Van

Helmont, the most ‘modern’ among chymical philosophers, whom even Boyle held in relatively high esteem.127 Duclos suggested two methods for inquiring into the principles of natural mixts: either by chymical resolution and inspection of the received components or by observing their generations and corruptions. His unmistakable Helmontian slant is revealed in his assertion that, “by the extreme resolution of natural mixts, nothing apparent remains but water. By observation of the generation of the mixts, water, too, is recognized as their primary matter.”128

127 On Van Helmont’s chymical views see Pagel (1982); Newman & Principe (2002), esp. pp. 56- 89 and chapter 6. 128 AdS, PV, 1: 2; “ceux qui ont procédé moin exactement a cette recherche des principes des mixtes naturels, par l’analyse chymique, ont pris pour principes et premières pièces constitutives le mercure, le sel, et le soulphre.”; italics added.

Discussing distillation, Duclos explained that an equally inaccurate chymical analysis of natural mixts is often interpreted as yielding five different substances: phlegm, spirit, oil, salt and earth. This, of course, refers to the widespread proliferation of elemental pentads, various combinations of peripatetic and Paracelsian elements and principles corresponding to substances received in distillation practices. These pentads arose from the addition of two of the Aristotelian elements—usually considered to be passive or inactive—to the Tria Prima, which represented the active elements. Duclos added that “three of these substances are said, by them [vulgar chymists], to be essential, the spirit, the oil and the salt,” explaining how the spirit is likened to mercury, the oil to sulfur, and the salt, which does not assume a different name, is only said to be either fixed or active. The phlegm and the earth, in contrast, are considered “purely material, lacking all virtue… vain and inefficient.”129

Much like Boyle, Duclos was critical of fire analysis and advocated solution chymistry.130 Unlike Boyle, however, Duclos was not dismissive of chymical knowledge in general. Instead he sought to separate himself from certain perceptions and traditions, which he was intent upon either rejecting or revisiting. In his ensuing discussion on the principles of natural mixts, he elucidated to the members of the assembly several key misconceptions concerning chymistry, while advancing his own ideas on the nature of matter and chymical analysis. As seen, Duclos spelled out the origin of terms like the pentad and its relation to the three principles. In the same vein, he referred to “them”—

129 AdS, PV, 1: 4. 130 Duclos’s views concerning distillation and solution analytical chymistry are discussed at length later on (see section on Alkahest, Corpuscles and Fire).

those who advocated and performed inaccurate chymical analyses—as the vulgar chymists.

These chymists, he asserted,

consider that phlegm is a basis or an elementary draft… lacking all essence, that the dead and damned earth (these are the terms of the art) is an excrement without energy… that these two weaken the virtue of the other three, and that is why they advocate the practice of their separation and removal.131

Similarly, he rendered the source of the Tria Prima as originating with the “hermetical philosophers, who desired that their sacred philosophical stone be composed of mercury, salt, and sulfur.” For Duclos, both these “mysterious philosophers” as well as the “vulgar chymists” accord the Tria Prima an elementary status in virtue of “some analogy between the three matters which compose the grand arcane of the Hermetics, and the three energetic substances… separated from several mixts by an imperfect analysis.”132

Duclos set himself apart from both groups while displaying affinity towards one of the most distinguished of “modern chymists,” who possessed the knowledge of a

“resolutive liquor, capable of penetrating and resolving radically all the mixed bodies.”

The allusion is to Van Helmont and his “alcahaliest” (alkahest), the utopian universal solvent. As if responding to Boyle’s concern over the “origin of forms,” Duclos maintained that, “we cannot be accused of having introduced, by this practice, new forms,

131 AdS, PV, 1: 4-5: “Ils jugent que le phlegme est un rudiment ou ébauche élémentaire… ny essensifie, que la terre morte et damnée (ce sont les termes de l’art) est un excrément sans énergie… que ces deux affoiblissent la vertu des trois autres, et pour ce ils veulent qu’on travaille a les séparer et rejeter.” italics added. 132 AdS, PV, 1: 4-5; “quelque analogie entre les trois matières qui composent le grand arcane des Hermétiques, et ce trois substances énergiques qu’ils scavent séparer de quelques mixtes par une analyse imparfaite.”

since nothing apparently remains but water.”133 Reasoning within a distinct Helmontian framework, Duclos suggested that an extreme resolution—such as the one brought about by the alkahest—would leave nothing behind but water. It followed that water was the

“primary matter” (raw matter) and the “primary component in the composition of natural mixts.”134 But even with a radical resolution, there was no certainty,

that the water is simple and devoid of anything else, although nothing else appears to be present, and we do not detect any signs of the previous fermentation, it [the water] can still be imprinted by some invisible efficient, capable of reproducing in it the new forms of salt, mercury, and sulfur, etc. We can only conclude that these primary forms were accidental; that they were the result of the action of some internal agent in the water.135

Materially, the radical resolution was conclusive, and the ultimate proof was empirical, for nothing “appears” or can be otherwise sensually “detect[ed]” in it. Yet, the water might still retain some insensible—hence immaterial—activity; an “invisible efficient” might transmute the water into salt, sulfur or mercury. In order to understand the “accidental” character of the Tria Prima we turn to Duclos’s distinction between perfect and imperfect natural mixts.

When an “impalpable and spiritual efficient” acts upon water, qua prime matter, it produces the Tria Prima, the multiple combinations of which can result only in the

133 AdS, PV, 1: 6-7: “Quelqu’un des plus renommez d’entre les chymiste modernes s’est vante de la connoissance d’un moyen fort expéditif de résoudre tous les corps mixtes… On nous accusera point d’avoir par ces travaux introduit de nouvelles formes, s’il ne reste en apparence que celle de l’eau.” 134 AdS, PV, 1: 2, 4. 135 AdS, PV, 1: 7: “nous n’asseurerons pas que cette eau soit simple et seule, quoyqu’il n’y paroisse autre chose, et qu’on n’y voye plus les effets de sa fermentation précédente. Elle pourroit ester encore empreinte de quelque efficient invisible, capable de reproduire en elle de nouvelles formes de sel, de mercure, et de soulphre, etc. Nous pouvons seulement conclure que ces premières formes estoient accidentelles ; que’elle estoient l’effect de l’action de quelque agent interne dans la matière de l’eau.” italics added.

production of “imperfect mixts.” “Perfect mixts,” on the other hand, are defined as

“partaking of life” or being vivified (to a certain extent) and cannot be produced by this

“alterative efficient of water.” In order to account for their occurrence, “it is necessary to assume a third type of principles of mixts, which modern chymists designate as arcana par excellence, for being the most perfect, and the most noble of all.” Therefore, Duclos surmised, “the principles of natural mixts are the material bodies, the alterative spirit, and the vivifying soul, or the arcanum.”136 Duclos’s depiction of perfect mixts as partaking of life is reminiscent of the increased complexity attributed to ‘organic matter’, for what distinguishes these mixts is that, “their mercuries, their salts, and their sulfurs are so diversified that they cannot originate only from the alterative spirits”; that is why there is a need to presuppose the existence of a “3rd principle more energetic and even less corporeal than the alterative spirit.”137

The significance of vitalist, animistic and Neo-Platonic dimensions of Duclos’s cosmology notwithstanding, it is his definition of the “corporeal” that is most revealing in the present context:

We name corporeal, not that which is extended in three dimensions geometrically; but that which is palpable. And we name incorporeal, and spiritual that which in this sense is not corporeal, and cannot be handled or touched sensibly.138

136 AdS, PV, 1: 3: “mixtes parfaicts” differ from “mixtes imparfaictes” in that they “ont quelque participation de la vie”; Duclos surmises: “ainsy les principes des mixtes naturels, sont le corps matériel, l’esprit altératif, et l’âme vivifiante, ou l’archée.” 137 AdS, PV, 1: 8: “il est nécessaire qu’il y ait en ces mixtes pairfaicts un 3e principe plus énergique et encore moins corporel que l’esprit altératif.” 138 AdS, PV, 1: 8: “Nous dison icy corporel, non pas ce qui est estendu en triple dimension géométrique; mais ce qui est palpable. Et nous appellons incorporel, et spirituel ce qui en ce sens n’est pas corporel, et ne peut etre manie ou touché sensiblement.”; italics added.

Recalling Fontenelle, it would seem that he called attention, inadvertently as it were, to a most consequential aspect in recognizing that chymistry “resolves bodies by sensible operations into certain gross and palpable principles such as salts, sulfurs, etc.” The tone of Fontenelle’s remark was of course derisive, purporting to contrast Duclos’s “gross” chymistry with Boyle’s “precise” physics. Duclos’s message, however, conveyed a radically different outlook. For Duclos, not all “principles” of natural mixts were “gross and palpable,” and while the Tria Prima might indeed be accessible “sensibly,” it was far from being elementary in the sense meant by either Fontenelle or Boyle. Out of three types of principles assumed by Duclos—body, spirit and soul—only the first was

“palpable” and it was, in fact, solely distinguishable—hence defined—by virtue of the fact that it could be “handled or touched sensibly.”

The corporeal for Duclos was not merely sensible but was manipulable, a proposition evocative of Aristotle’s implicit belief in the primacy of the sense of touch.

According to Duclos’s SER, the chymist worked with matter in the form of substances and it was the knowledge of the substances and the complex art of manipulating them that was unique to the chymist. Above all else, Duclos’s “principles,” and subsequently his SER, were tightly linked to experimental demonstration. At the end of the memoir on the

“principles of natural mixts,” Duclos stated clearly that, “the examination of all these things may take us a rather long while, and in order to research, discuss and acquire [this] knowledge we will have to perform many observations and experiments.”139 This is

139 AdS, PV, 1:14: “L’examen des toutes ces choses nous pourra exercer assez longtemps, et nous aurons sur cela beaucoup d’observations, et d’expérience à faire, pour rechercher, discuter et sçavoir.”

indeed a far cry from the “Chymists” Boyle referred to, who, “without proving, take

[suppositions] for granted; and upon which Depends the Validity of the Inference they draw from their Experiments.” Drawing on his outline for the research of the “principles of natural mixts” and his vision of chymical experimentation, Duclos challenged “the

Validity of the Inference” that Boyle drew from his own experiments, most notably those dealing with saltpetre, a substance of central significance for both natural philosophers.140

Duclos’s reading of Boyle’s Essay on Niter offers a preliminary understanding of Duclos’s

SER in the context Boyle’s most radical reformative suggestion: the submission of chymical phenomena to the principles of the corpuscularian philosophy. The discussion discloses Duclos’s relation to particulate theories of matter and to mechanistic agendas, as applied to chymistry.

PARTICLES OF SALTPETRE

As part of his examination of the Physiological Essays, during the assembly’s inaugural Saturday meeting for the year 1669, Duclos announced having reached

the second part of Mr. Boyle’s book, which contains two treatises, in which the author attempts to reconcile the principles of the corpuscular philosophy with the experiments of the chymists and to account for these experiments by the doctrine of atoms.141

140 See Debus (1964). 141 AdS, PV, 6: 1r: “la seconde parties de livre de m. Boyle, laquelle contient deux traittez, ou cet autheur a tasché d’accommoder les principes de la philosophie corpusculaire aux expériences des chimistes et de rendre raison de ses expériences par la doctrine des atomes.”

The reference is to Boyle’s Specimens of an Attempt to Make Chymical Experiments

Useful to Illustrate the Notions of the Corpuscular Philosophy. Claiming chymistry’s usefulness for making “some Meliorations… of Mineral and Metalline Bodies, and many excellent Medicines for the Health of Men, besides divers other Preparations of good use in particular Trades,” might suffice, Boyle suggested, to persuade some people that chemical pursuits were not a complete waste of time; “yet this would scarcely suffice to manifest it to be useful to Philosophy.” In order to demonstrate the validity of the latter point—and hence to promote chymistry as an inseparable part of natural philosophy—

Boyle set out to prove that “Chymical Experiments might be very assistant even to the speculative Naturalist of his Contemplations and Enquiries.”142 Subsequently, Duclos noted, “out of all the notable practices of chemistry” Boyle “had chosen the resolution and reintegration of saltpeter.” Duclos dedicated two consecutive memoirs (January 7th and

12th) to the evaluation of Boyle’s essay on saltpeter, the Physico-Chymical Essay

Containing An Experiment with some Considerations touching the differing Parts and

Redintegration of Salt-Petre.143

In the spirit of his preceding Physiological Essays, Boyle began by complaining that saltpetre, “in that form wherein it is sold in Shops, it be no very obvious concrete.” Its significance, nonetheless, could hardly be overstated:

it is to be found in so great a number of Compound Bodies, Vegetable, Animal, and even Mineral, that it seems to us to be not only one of the most Catholick of Salts, but so considerable an Ingredient of many sublunary

142 Boyle, CPE, p. 86. 143 AdS, PV, 6: 1r-v.

Concretes, that we may justly suppose it may well deserve our serious enquiries.144

Duclos remarked with irony that despite deeming “saltpetre… as worthy of the most exact study,” Boyle excused himself for not having taken the time to pursue such inquiries, due to his “grand affairs.”145

Boyle first attended to the resolutive procedure. Four ounces of purified saltpetre were taken and “melted into a limpid Liquor,” into which a “small live Coal” had been cast, which “presently kindled it, and made it boil and hiss, and flash for a pretty while.”

The procedure was repeated several times by subsequent additions of “glowing” coals “till the Nitre would neither fulminate nor be kindled any more.” The “remaining fix’d Nitre” was then divided into two equal parts. The first part was dissolved in “fair water” to which

Boyle added “Spirit of Salt-petre,” until the effervescence had died down. After being filtered, the resulting mass was exposed to open air. The second part, which had not been dissolved, was likewise mixed with the “same Spirit till the hissing and ebullition were altogether ceas’d,” after which the sample was exposed “in an open glass Jar to the air in the same window with the former.” Judging by “their manner of burning, as their shape,”

Boyle concluded that in both instances the resulting “Crystals” were of saltpetre. Finally, he embellished his qualitative observations with a quantitative consideration: “the weight of the Spirit of Nitre requisite to be drop’d on, till all the ebullition made betwixt that

144 Boyle, CPE, p. 93. 145 AdS, PV, 6: 1v: “salpestre qu’il estime digne d’estre exactement recherchée.”

Liquor and the Solution of fix’d Nitre were ceas’d, did not amount to so great a weight as the Salt-Petre lost in its detonation, and yet fell not much short of it.”146

Boyle proceeded to point out what he deemed as the most significant potential consequence the experiment:

if upon further and exacter tryal it appears that the whole body of the Salt- Petre, after it’s having been sever’d into very differing parts by distillation, may be adequately re-united into Salt-Petre equiponderant to it’s first self; this Experiment will afford us a noble and (for ought we have hitherto met with) single instance to make it probable that that which is commonly called the Form of a Concrete, which gives it it’s being and denomination, and from whence all it’s qualities are in the vulgar Philosophy, by I know not what inexplicable wayes, supposed to flow, may be in some bodies but a Modification of the matter they consist of, whose parts by being so and so disposed in relation to each other, constitute such a determinate kind of body, endowed with such and such properties; whereas if the same parts were otherwise disposed, they would constitute other bodies of very differing natures form that of the Concretes whose parts they formerly were, and which may again result or be produc’d after it’s dissipation and seeming destruction, by the re-union of the same component particles, associated according to their former disposition.147

Boyle sought to advance an explanation based on the experimental consequences of the reintegration experiment according to which the “Form of a Concrete… [and] all it’s qualities”—so poorly accounted for in the “vulgar Philosophy”—would be deduced from much stronger premises: the “Modification[s] of the matter” of the substance at hand. This

“Modification,” moreover, which governed the substance’s “properties” and “being,” proceeded from the relative disposition of its particles. Given his different outlook, Duclos was suspicious of Boyle’s prediction of such “noble” reinterpretations of a theme as pivotal as the “Form of a Concrete” on the basis of findings afforded by this experiment.

146 Boyle, CPE, pp. 94-96. 147 Boyle, CPE, pp. 107-108.

For Duclos, saltpetre resulted from “the condensation of air in a sulfurous salt,” and it was this condensed air that was the cause of its fulmination. “It will suffice,” he maintained,

“to elucidate the composition of saltpetre for examining the way by which Mr. Boyle had reasoned concerning some changes in this substance,” referring to its resolution and reintegration.148

Like Duclos, Boyle’s account of the various “changes” observed in saltpetre, followed from his conception of its composition. His preliminary remark to these explanations reveals his approach. “This Experiment,” he opined, “seems to afford us an instance by which we may discern that Motion, Figure, and Disposition of parts, and such like primary and mechanical Affections… of Matter, may suffice to produce those more secondary Affections of Bodies which are wont to be called Sensible Qualities.”149

Boyle first discussed the “Tangible Qualities” such as “Heat and Cold,” and explained that saltpetre is commonly perceived to be, in essence, a very cold body. “When the Parts of this so cold Body” are combined, however, they “immediately agitate each other with great vehemency,” which results in the production of a great amount of heat, “as if Heat were nothing but a various and nimble motion of the minute particles of Bodies.”

This conclusion rests upon the observation that as long as the “agitation lasted, so long the heat endur’d [but]… when the motion ceas’d, the heat also vanish’d.”150 Duclos found this interpretation wanting, since “it is indeed motion which brings about the effervescence, but

148 AdS, PV, 6: 3r-v: “par la condensation de l’air dans un sel sulphure.”; “Il suffit d’avoir icy expliqué la composition de salpestre pour servir a l’examen des raisons de Monr Boyle sur quelques changements qu’il a observez en cette matière.” 149 Boyle, CPE, p. 98. 150 Boyle, CPE, p. 99.

Mr. Boyle has not indicated the cause of this tumultuous motion,” which, Duclos added,

“he probably could not have attributed to the figure and disposition of particles.”151

According to Duclos, Boyle failed to account for the “cause” of the effervescence, the tumultuous motion and the ensuing heat. According to his SER, in particular as we have seen in the context of his operative epistemology, Duclos’s perception of chymical causality was closely linked to the manipulation and palpability of substances. From

Duclos’s standpoint, Boyle’s corpuscular interpretation—associating the effervescence with the great “agitation” between the “Parts” of the saltpetre—was not a proper causal explanation precisely because any reliance on the imaginary, indeed speculative, “figure and disposition of particles” could not comprise a valid chymical explanation. Duclos did not merely challenge the explanatory prowess of Boyle’s mechanico-corpuscular argument: he denied its plausibility. Duclos further indicated that whereas the mixture of iron with the spirit of saltpetre “excites a very violent motion and a great heat,” the dissolution of camphor in the same acid was devoid of any such effects. Whereas the camphor, Duclos explained, was entirely oily and hence lacks any salt, the iron was rich in sulfurous salt. It follows that the tumultuous motion excited during the dissolution of iron in the spirit of saltpetre was due to the “mutual and reciprocal action of salts of different qualities.”152

151 AdS, PV, 6: 4v: “c’est bien le mouvement qui fait l’effervescence, mais Mr Boyle n’assigne pas la cause de ce mouvement tumultueux, que peut estre il n’a pû trouver dans la figure & dispositions des particules.” italics added. 152 AdS, PV, 6: 4v-5r: “C’est donc par l’action mutuelle et réciproque des Sels de diverse qualité, qu ce mouvement est excité.”

Resuming his discussion, Duclos noted that, “the cause of the colors which the saltpeter assumes while in the fire, during its calcination by coal, is not adequately explained by the new disposition of particles.”153 Boyle had previously described the calcined, or “fix’d” nitre, as being possessed “of a deep colour betwixt blue and green.”

When mixed with the respective acid (spirit of saltpeter), this color disappears.

Advancing, once again, a thoroughly mechanistic account, Boyle attributed this change of color to “that disposition of parts, whereby the light reflected to the eye, was so modify’d as to produce that colour being now alter’d.”154 Boyle assumed that the cause of the change in the colors owed to the (re)configuration of the corpuscles of saltpetre. But

Duclos deemed Boyle’s interpretation as ill-conceived, attributing the color change to an

“exaltation of the sulfur” contained in the saltpetre. Admittedly, Duclos added, the sulfur of the saltpetre did not, solely by itself, occasion the various colors and color changes—as observed in different other chymical reactions—but it did enhance and stimulate those of other substances. For instance, “the fixed salt of common vitriol fulminated with sulfur and saltpetre turns green”; should the resulting substance be dissolved in water, it would become ruby-red, after which it would change into blue and finally into violet. Duclos attributed all these changes to the activity of sulfur.155 In contrast, Boyle’s corresponding examples were interpreted in accord with mechanico-corpuscular notions. Hence, saltpetre, upon distillation, “although it seem to have nothing of kin to Rednesse,” gave off

153 AdS, PV, 6: 5r: “la cause des couleurs que le salpestre contracte au feu en sa calcination par la charbon n’est pas fort bien expliquée par la nouvelle disposition des particules.” 154 Boyle, CPE, pp. 96, 100. 155 AdS, PV, 6: 5r: “le sel fixe du vitriol commun fulmine avec du soulphre et du salpestre devient vert.”

“blood-red fumes… which fall again into a Liquor that has nothing of red in it.” However,

“by a new disposition of its parts conjoyn’d with those of its reimbib’d Spirit, [it] becomes again somewhat Diaphanous.”156

Similarly, according to Duclos, the disagreeable smell of the spirit of saltpetre owes to the rarefaction of its sulfur.157 In his comments concerning the “offensive smell,” which proceeded from the “Spirit of Petre,” Boyle refrained from advancing a causal corpuscularian explanation, limiting himself to descriptive remarks. In the case of the mixture of spirit of saltpetre with “its own fix’d salt,” “stinking exhalations” were emitted, which Boyle merely ascribed to a “conflict” between the two substances.158 Duclos was quick to chide Boyle’s account of smells for failing to elucidate their “cause”; he added wryly that “Mr. Boyle could not find the cause according to the corpuscular philosophy since he did not mention anything” in relation to it. Embellishing his anti-mechanistic rhetoric, Duclos admitted that Boyle has “genuinely declared” the limitations of “this doctrine” in maintaining that, “it is not sufficient for explaining everything.”159

Duclos proceeded to claim that “Mr. Boyle is not well acquainted with saltpetre,” a statement in support of which he read to the assembly Boyle’s observation that saltpetre,

156 Boyle, CPE, p. 100. 157 AdS, PV, 6: 5v. 158 Boyle, CPE, p. 101. 159 AdS, PV, 6: 5v: “M. Boyle n’en a pas trouvé la cause selon sa philosophie corpusculaire, puisqu’il n’en a rien dict.” Duclos here refers to some comments made by Boyle “apres en la page 23” of the Latin edition; possibly to Boyle’s qualification that bodies “whose Organical parts require a much more artificial and elaborate disposition or contrivance of their component particles, cannot be safely judg’d of, by what is possible to be preform’d in a body so simple and slight a contexture as is Salt-Petre.” (Boyle, CPE, pp. 108-109).

“not onely is inflammable, but burns very fiercely and violently.”160 Boyle described an experimental conundrum, for which, he confessed, he had neither the solution nor the

“time to enquire after” it. What puzzled Boyle was that saltpetre seems to be invariably

“inflammable” and, moreover, “burns very fiercely” whenever it comes in contact with a

“glowing coal.” However, “if the same Nitre be plac’d in a [very hot] Crucible… the strange Salt will be thereby melted, but not kindled.”161 For Duclos, the issue was easily explicable. Nor did Boyle’s attempt to conceal his lack of knowledge behind a weak excuse go unnoticed. For the second time in this memoir, Duclos relayed Boyle’s words to the assembly; the latter’s obscure apologetic claim concerning the allegedly “strange” behaviour of saltpetre, “the Reason of which Phænomenon I must not now (but may on another Occasion) spend time to enquire after.”162

Whether Boyle made the excuse in order to vindicate his own measure of confusion or embarrassment, as Duclos hinted, is of little significance, although Boyle seemed equally uncomfortable with the causes of the “Inflammableness of Bodies,” which were to be treated more particularly “else-where.”163 Duclos’s solution to the mysterious

“Phænomenon,” however, is revealing. Saltpetre would not catch fire from a flame of a candle; nor would it inflame in kindled spirit of wine or in heated and kindled oil; it would not inflame when applied to melted lead, silver or gold. It would only inflame and fulminate when put together with heated earthy combustibles, as when mixed with coal,

160 AdS, PV, 6: 5v-6r: “Nitrum (quo nihil proclivius ad concipiendas flammas, nihil quod vehementiore conflagret incendio)…” Boyle (1661), p. 15 (Essay on nitre…); Boyle, CPE, p. 102. 161 Boyle, CPE, pp. 102-103. 162 AdS, PV, 6: 6r: “Cujus phaenomini causam non hic, sed alibi forte, sum redditurus…” Boyle (1661), p. 15; Boyle, CPE, p. 103. 163 AdS, PV, 6: 6r; Boyle, CPE, p. 102.

sulfur, sulfurous minerals, melted tin or white-hot iron. The more sulfurous salt these combustibles contained, the greater the resulting inflammation. This is why, Duclos held, the saltpetre must be mixed with coal, a substance rich in sulfurous salt, found in its ashes after it had undergone combustion. Contrary to Boyle’s opinion, then, Duclos stated that saltpetre was not inflammable: its fulmination “proceeds solely from the contrariety of the air, which it contains, and the fire which sets aflame the combustible matter with which it is mixed.”164

Duclos opened his second memoir—of the two dedicated to the appraisal of the

Physico-Chymical Essay on saltpeter—by asserting that “it is easy to resolve the question that Mr. Boyle poses… [for which he] could not find the solution in the corpuscular philosophy; but which is easy and straightforward in [the philosophy] of the chymists.”165

Boyle’s query, which prompted Duclos to commend the chemical philosophy vis-à-vis the

“corpuscular philosophy,” reads:

Whence it proceeds that whereas the body of Salt-Petre when committed to Distillation is oftentimes very well dry’d, and consists of Saline parts which are generally accounted to be of a very dry nature, yet the spirits of Petre forc’d by the fire into the Receiver should not, like Sal-Armoniack, and some other bodies distill’d with the like heat and vessels, adhere in the form of Sublimate to the Receiver, but fall into a liquor, which does not, for ought we have seen or heard of, either totally or in part coagulate again in the cold, as we have seen Spirit of Urine and other volatile liquors… often do.166

164 AdS, PV, 6: 6r-v. 165 AdS, PV, 6: 7r-v: “il est aisé de resoudre la question qu Mr Boyle a faict… Mr Boyle n’avoit pas trouvé la solution de cette question dans la philosophie corpusculaire ; mais elle est facile et prompte en celle des chimistes.” 166 Boyle, CPE, p. 103.

Boyle was perplexed as to why a body that is dry in essence like “the body of Salt-Petre,” when distilled resulted in a liquid and did not sublimate; “Sal-Armoniack” and “Spirit of

Urine” provided counter-examples. We have noted Boyle’s distrust of the “vulgar philosophy,” in accounting for the “Form of a Concrete.” Duclos provided the answer according to the philosophy of the “chymists.” Traditional chemical philosophers, he noted, were well acquainted with the observation that earth has a strong “symbole”— chymical affinity (in line with the principle of like acts upon like)—with sulfur, by virtue of its dryness. When earth was mixed with a sulfurous salt, the earth rose in the fire, during distillation, together with the salt, thus impeding the disengagement of the salt’s

“fluid spirit,” as could be observed in “Sal-Armoniack” or the volatile “Spirit of Urine,” as

Boyle pointed out. Duclos interpreted the distillation of saltpeter in the following way: when the salts were less sulfurous, their acid and mercurial (acido-mercurial) spirits

“detach easily from the earthy parts, which remain in the retort since they are less

[strongly] united to the mercurial salts, towards which they posses less liking.” Since these mercurial salts were humid, Duclos explained, the heat of the furnace resolved them into liquid spirits, which having left their earthy parts behind, in the bottom of the retort, retained their liquidity. This was because the earthy parts occasioned the coagulation of these salts.167

Boyle evoked the experiment on the “Redintegration of Salt-Petre” in support of his criticism of fire analysis—relayed extensively in the Sceptical Chymist—as perceived

167 AdS, PV, 6: 7v-8r: “se destachent facilement des parties terrestres qui demeurent dans les cornues, parce qu’elles sont moins unies aux sels mercuriels, avec lesquels elles ont moins de convenance.”

by “those vulgar Chymists who presume confidently (and indiscriminately enough) to ascribe to each of the heterogeneous Ingredients, or (in their language) Principles of a

Concrete analys’d by the fire, the virtues and properties… of the entire body.” When the saltpeter was distilled, “the volatile liquor and fix’d Salt into which it is reduc’d by the fire, are endowed with properties exceeding different both from each other, and from those of the undissipated Concrete.” The resultant spirit of niter possessed similar qualities to those of “acid spirits”; the fixed niter was of an alkaline nature and “participates the qualities belonging generally to lixiviate Salts.” Saltpeter, however, was an altogether different substance, a “peculiar sort of Salt discriminated by distinct properties” in relation to its latter two constituents. Boyle concluded by pointing out the “vast disparity in the effects and operations of these three bodies.”168 Duclos agreed with Boyle “that the parts of the mixtes separated or exalted by the fire acquire qualities they had not possessed before.”

But it might also be the case, he remarked, that the fire did not produce these qualities anew, that they may have preexisted and the fire merely rendered them “more active.”169

Doubtless, the spirit of saltpeter was more corrosive than saltpeter and could dissolve silver and mercury; the calcined saltpeter, alkalized by the coal, acquired new qualities as well. However, Duclos inquired,

What arguments can be adduced in favor of the corpuscularian doctrine that could be acceptable and informative? It is manifest that the spirit of saltpeter is rendered by distillation less earthy and more subtle and that it thus penetrates more efficiently into the pores of silver and of mercury; but beyond this tenuity of particles, occasioned by the fire in distillation, there

168 Boyle, CPE, pp. 105-106. 169 In the Scpetical Chymist Boyle argues against fire analysis on the same grounds. For a discussion of the niter experiment in the context of qualities and substantial forms see Newman (2006), pp. 208-215.

must exist in saltpeter and other similar salts some kind of peculiar quality regarding the dissolution of metals… As to saltpeter alkalized by the coal, it is a composed subject, the qualities of which, assumed during this preparation, do not originate solely from the fire and its actions on the particles of this calcined salt, but also from the sulfurous salt of the coal which mixes with this saltpeter and which renders it capable of resolving sulfurous substances.170

Arising from his reading of Boyle, this passage captures several key features of Duclos’s chymical SER; it provides crucial clues concerning Duclos’s conception of chymical analysis—“distillation” and “dissolution” in particular—to which we shall turn shortly.

Duclos admitted the transformation of qualities but rejected Boyle’s use of the

“corpuscularian doctrine” to explain this change, as it occurs in the redintegration of niter experiment. Yet at the same time he discussed the “pores” of metals, the “tenuity of particles” as “occasioned by the fire” and the “particles” of what Boyle designated as the

“fix’d salt” of saltpeter. This apparent discrepancy opens a path for a more accurate understanding of the nature of the criticism Duclos adduced against Boyle’s corpuscularian style of reasoning. As part of his argument, Boyle advanced an explicit distinction, encapsulating a metaphysical requirement:

it is not barely an indefinite nimbleness of motion, and activity of the particles… that enables them to perform each of their particular effects: for

170 AdS, PV, 6: 9r-v: “Quels arguments en peut on tirer, pour favoriser la doctrine corpusculaire, qui soient recevable & communicants? Il est manifeste que par la distillation l’esprit du salpestre est rendu moins terrestre et plus subtil, & qu’ainsy il pénètre mieux dans les pores de l’argent et du mercure; mais oultre cette ténuité des particules produicte pa le feu en la distillation, il faut qu’il y ait dans le salpestre & dans les autres semblables sels quelque qualité propre a la dissolution de métaux… Quant au salpestre alchalise par le charbon c’est un subiect compose dont les qualitez acquises en cette preparation ne viennent pas seulement du feu & de son action sur les particules de ce sel calcine; mais aussi de sel sulphure du charbon qui s’est mesle avec ce salpestre et qui le rend capable de résoudre les matières sulphurées.”

to the production of some of these there seems requisite, beside perhaps a Modification of their Motion, a determinate Figure of the corpuscles.171

Whereas Boyle believed, as we have seen, that the redintegration experiment provided an instance for discerning the “Motion, Figure, and Disposition of parts,” Duclos invoked, at the particulate level, only motion and its derivative particulate “tenuity.” Fire, for Duclos, has but a limited influence upon substances, rendering the acid “less earthy and more subtle.” Such increased mobility and activity brings about an enhanced “tenuity of particles.” “There is hardly any appearance,” Duclos added, to support the idea that “it should be the diverse disposition and configuration of particles of saltpeter which causes the difference in detectable qualities, which render it [saltpeter] either acrid, acidic, sulfurous, mercurial, fiery, or cool, etc.” These differences might be better attributed to the various substances comprising saltpeter and to their “alternating predominance.” Some were manifestly sulfurous or igneous, others airy, “as can be observed in the confection and resolution of saltpeter.”172 Furthermore, Duclos’s supposition of a “peculiar quality,” enabling saltpeter to dissolve metals, drew upon experimental evidence. A solution of raw saltpeter in common water dissolves silver efficiently with the addition of oil of vitriol and saltpeter would dissolve even gold when boiled together with a mixture of common salt an alum, “without the addition of any corrosive liquor.”173 Duclos’s view of the relation between fire, heat and chymical mixts was intricately related to his understanding of chymical analysis and experimental method.

171 Boyle, CPE, p. 105; italics added. 172 AdS, PV, 6: 11r-v. 173 AdS, PV, 6: 9v.

174 DUCLOS ON BOYLE’S “UN-SUCCEEDING EXPERIMENTS”

Boyle began On the Unsuccessfulness of Experiments by raising a problem. It was often the case, he maintained, that many experiments, published or otherwise communicated by practitioners, turned out to be “false or unsuccessful.” Regardless of the reliability of the source, experiments were “either not at all succeeding constantly, or at least varying much from… [the] expected.” The experimental realm was in fact unreliable and contingent in essence. Although the source of this problem was elusive, Boyle distinguished the “causes of this unsuccessfulness” as originating either from “the particular or mistaken properties of the Materials imploy’d… [or from] the handling of these Materials.” Experimental contingency was subsequently due to issues of matter and manner; materials and methods employed. By inference, matter was unstable and forms were impermanent.175 Duclos agreed that matter and manner were problematic categories and entities but insisted that with careful study of the literature, coupled with supreme workshop proficiency, experiments could be replicated successfully and distinct classes of chemical reactions could be discerned. Moreover, permanent and stable patterns of matter could be recognized.

On 7 September 1668, Duclos conducted with ease and confidence, in front of the assembly, an allegedly difficult experiment—the preparation of the star regulus of antimony—in support of his claim that chemical predictability could be achieved by a

174 Parts of this section are loosely based on Boantza (2007b). 175 Boyle, CPE, pp. 37-38.

skillful experimenter.176 Boyle, on the other hand, undermined the regularity of such operations:

…antimony… is wont by almost all men without hesitancy to be look’d upon as being all of it of the same nature as well as denomination; yet he that will take the liberty to suspect that they may be deceiv’d in that opinion, and then heedfully observe the differing progress and event of experiments, may very well discern, that there is as well a difference in minerals of the same kind, as there is in vegetables and animals of the same species.177

Boyle followed this up with an analogy: “the white-rose, the red-rose, and the Damask- rose differ much from one another, though all three be roses”; the same applied to oranges, dogs, etc. The differences between vegetables or animals, according to Boyle, were more obvious to the eye than the differences between various specimens of metals and minerals.178 Duclos rejected the analogy and its import, namely, that the various samples of what appear to be the same metal may constitute different species of matter. The main difficulty when working with antimony, for instance, was in the way it is handled. In this context, Duclos mentioned Basil Valentine’s Triumphant Chariot of Antimony,179 in which the author, in line with Duclos, stressed the following dictum:

nature knows not how to erre, if rightly governed by a faithful steward, to whose care she is committed: if thou (therefore) erre, because thou hast not loosned nature, and freed her from the body wherto she’s captive; learn the theory better, & more accurately attend thy work, that thou may’st be

176 AdS, PV, 4: 197r-v; “M. Boyle a avancé que l’Etoile qui paroist quelquesfois sur le Regule d’antimoine, ne ce faict que par hazard, et qu’il n’y a point de manière infaillible de la faire. Cependant l’opération ayant esté faicte trois fois de la manière que M. Du Clos a ordonné.” 177 Boyle, CPE, p. 41. 178 Boyle, CPE, p. 41. 179 AdS, PV, 4: 252r-253v: “M. Boyle… a jugé que la difficulté de faire ce regule estoilé procedoit de la différence des matières, & particulièrement de l’antimoine… Basile Valentin a dict en son char Triomphal de L’antimoine, que c’est a la manière d’opérer qu’il faut prendre garde.”; Duclos concluded: “J’ay observe que c’est seulement de L’opération que cela dépend.”

acquainted with the true fundamental knowledge of separating all things, and this is a chief, and most principal thing.180

Against the analogy pertaining to the difference between species of minerals and metals

Duclos held that “the alloys that one makes of silver and copper with gold change the karat of the gold without creating a new species.” The issue at stake, then, is the mixture and degrees of perfection rather than any diversity of species; the differences being particular, not essential.181

Duclos noted that the assembly had witnessed the successful preparation of the Star

Regulus using two different kinds of antimony, common and Hungarian.182 Here, too, a formal yet substantive difference emerges. Boyle’s rhetoric famously overflowed with sociable reports of anecdotes and the testimonies of “acquaintances” and other witnesses for whose integrity Boyle vouched, frequently describing them as “famous” or

“ingenious.”183 In contrast, Duclos’s reports were rendered in a forthright manner and straightforward language.184

Amplifying his emphasis on the diversity of matter Boyle asserted that “’tis vulgarly known, that there is a great difference between vitriols that are reputed to be merely of the same metal.” Duclos remarked that the only difference among vitriols from the same metal derived from the preparation of the metal and the way the vitriol was

180 Valentine (1661), p. 8. 181 AdS, PV, 4: 244v-245v. 182 AdS, PV, 4: 254r. 183 See, for instance, Boyle, CPE, pp. 38-42, where Boyle invariably refers to: “one of the eminentest and soberest Chymists,” “learned and severe Witnesses,” “an excellent Chymist of my acquaintance,” “an ingenious Goldsmith,” etc. 184 The memoirs represent a transcription of his lecture-demonstrations conducted in front of a set assembly, the members of which are identified and known.

extracted from it. He described an experiment that yielded two vitriols extracted from a ferrous Auteuil marcasite. The vitriols were extracted by use of common water: the first to congeal was of a green color and had an astringent taste while the second to congeal was completely white, of a distinct shape and possessed of an acrid and piercing taste.

Concerning the marcasite, Boyle noted the possibility that “rain may work upon those other substances formerly coagulated with them, and thereby imbue some parcels of the vitriol made of them with qualities other than are essential to the nature of vitriol, or belong ordinarily to it.”185 Again, Boyle alluded to “essential” differences in “the nature” of substances. Duclos insisted that the cause of the difference rested upon the fact that two consecutive coagulations had taken place. Initially, he explained, a most subtle part of the sulfur (from the marcasite) rose to the surface of the water and mixed with the saline part

(of the vitriol), rendering it green and astringent. The second time, it was the other saline portion of the vitriol that became reduced into crystals. The rest of the remaining sulfur, being too earthy, was left in a viscous and gelatinous state. Duclos, in his explication, drew upon the nature of the process, employing “sulphur,” “salt” and “earth” in an operative manner. He further pointed out that “transparent and crystalline” salts obtained from metals by means of “corrosive liquors” were not to be regarded as “real vitriols” but rather as the “saline spirits” of those liquors, “corporified and coagulated in the dissolved metals.”186

185 Boyle, CPE, p. 47. 186 AdS, PV, 4: 257v-258r: “ce sont les esprits salins de ces liqueurs corrosives, corporifiez et coagulez dans les metaux dissouts ; car ces dissolvants, selon l’axiome des chymistes qua actione dissolvunt coagulantur eadem [dissolve by the same means by which they congeal.]”

In his Essay of Un-Succeeding Experiments Boyle discussed chymical method and in particular, “the contingencies to which experiments are obnoxious upon the account of circumstances.” In this context, he evaluated the (un)successfulness of transmuting silver into gold by recounting he story of a “Dr K.,”187 a friend of whom

by digesting Gold with an Aqua Fortis was able to separate the Tincture or yellow Sulphur from it, and made it volatile (the remaining body growing white) and that with this golden Tincture he had, not without gain, turn’d Silver (as to part of it) into very perfect Gold. Upon which advertisement the Doctor speedily returning to his Laboratory, did himself with the same Aqua Fortis divers times draw a volatile Tincture of Gold, which did turn Silver into true Gold… out of an ounce of Gold he drew as much Sulphur or Tincture as sufficed to turn an ounce and a half of Silver into that noblest Metal.188

Unfortunately, the doctor failed to grow “rich by this experiment” as he was not able to replicate it consistently. He ascribed the failure to the “Aqua Fortis” (spirit of nitre)189 in use while Boyle cautioned that “’tis not improbable that the disappointment proceeded from some other more abstruse cause,” stressing, once more, the “contingency of such experiments,” derived from the unreliable nature of experimental performance.190 Duclos noted that had Boyle read Otto Tachenius’s Hippocrates chymicus he would have been acquainted with the experimental qualification according to which different degrees of fire occasion, in acids, different dispositions to act upon gold (or metals in general). That which is produced by a mild degree of fire (e.g. sand bath) will act upon gold by extracting only its sulphurous tincture, without corroding its entire body, as acids obtained by

187 Identified by the editors of the Boyle Works as Johann Sibertus Kuffeler (1595-1677), see Boyle, CPE, p. 46, note b. 188 Boyle, CPE, p. 57. 189 I.e. nitric acid. 190 Boyle, CPE, pp. 58-59; Here Boyle refers to testimonies by, e.g., Glauber and Mirandola.

extreme degrees of heat (e.g. open fire) do. “Aqua Regis,”191 for instance, being of a

“mercurial nature,” acted violently upon the whole metallic body, bringing about a physical discontinuation of its mass, which in turn resulted in a complete metallic dissolution. Subsequently, no actual “separation” could take place and no “extraction” was possible. The sulphureous part of metals could be obtained only by menstrua that possessed the propensity to unite to that component, according to the Paracelsian-Hermetic precept—like acts upon like (affinity)—with the sulphureous element being the common denominator; Duclos employed terms like “symbolic” and “symbolicity.”192

Duclos’s argument rests upon three additional premises. First, an “axiom of the hermetic doctrine, which holds that all metals are composed of mercury and sulphur.”

Duclos alluded to Paracelsus’s Archidoxis to promote the distinction between the

“mercurial” and the “sulphureous” components of gold.193 The analogous distinction is made clear in the fourth chapter, “Of the Extraction of the Quintessence out of Metals” where Paracelsus similarly observed the diversity of phenomena encountered by “many men [who] have (in our time) attempted and experienced very many things in them

[metals].” Subsequently, he remarked, metals

are to be divided into two parts, viz. into their Quintessence, and into their body; both which are liquid and potable, and will not be premixed together: but the impure body, turns forth the Quintessence to its superficies, even as the Colostrum, or cream is Separated from the milk. By this way are made two fatnesses, or viscuous liquors out of Metals, the which liquors are to be

191 Mixture of nitric acid (aqua fortis) and hydrochloric acid (muriatic acid). 192 AdS, PV, 4: 320v-322v: “Les soulphres qui déterminant et spécifient les métaux ne peuvent estre extraictes et séparez que par des menstrues Symboliques et partant Sulphurez qui n’agissent que sur ce qui leur est semblable.” 193 AdS, PV, 4: 323v-324r.

separated. As for the fatnesse of the Body, tis always white, even of all the Metals; but their Quintessence is coloured.194

Duclos identified the coloured “Quintessence” as the sulphur and the white “Body” as the mercury; the mercury represented the corporeal and the sulphur the incorporeal. Secondly,

“the dissolution of one metal facilitates that of another metal.”195 This is seen in the case of the vegetation of quicksilver in spirit of nitre, which was encouraged by the dissolution of silver in the acid: the diminished, or weakened, part of the silver in the solution dissolved part of the quicksilver while the remaining part attracted the silver from the solution, resulting in its exaltation in silvery (plant-like) formations throughout the solution.196

According to the final supposition, in accord with Hermetic and Paracelsian traditions, the causes of metallic transmutations were to be found in their sulphur(s).197

For Duclos, metallic transmutations were commonplace; in particular those in which iron turned into copper and cinnabar (HgS) into silver, as various practitioners had demonstrated.198 Duclos maintained that certain liquors, endowed with sulphureous spirits, when applied to gold or silver, acted symbolically upon the sulphureous portion of the metals and subsequently not only dissolved the metal’s body—consisting of a mercurial essence—but exalted it to a degree of fermentative activity, whereupon it assumed a different specification, that is, underwent transmutation. Such transmutations involved

194 Paracelsus (1661), pp. 47-48. 195 AdS, PV, 4: 322v. 196 AdS, PV, 4: 324r-324v. 197 AdS, PV, 4: 322v. 198 AdS, PV, 4: 324v: “les changement du fer en cuivre et du cinabre en argent sont vulgaires.”

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fermentative processes, occasioned by the symbolic action of the sulphureous spirits on the metallic sulphur(s), resulting in changes that took place at the mercurial level.199

According to Duclos’s explanation, while the change was occasioned and brought about by the sulphur, it actually came into being in the mercury.

Duclos elaborated upon the view that the metallic sulphurs were the cause of metallic transmutations, and offered a more sophisticated interpretation. In accord with

Helmontian perceptions, “each metal contains two kinds of sulphur,”

one is internal and generic, by which its [the metal’s] mercury coagulates and renders it metallic and the other is external and supplements the other [sulphur] in specifying the metallic body of each particular metal. It is the second sulphur, which is referred to as embryonic and may be separated without the destruction of the metal, which remains in a fusible and malleable bodily state, but not without the loss of its specific nature [l’estre spécifique]. It is the embryonic sulphur, rendering the specific form to the generic subject of the metals, which can also bring about transmutation of a specific metal, if extracted from one metal and then applied to another.200

The transmutation of silver into gold, Duclos remarked, occured when “the embryonic sulphur of gold is extracted from its subject by a sulphureous spirit” (esprit sulphuré) and applied to the silver to imprint gold’s embryonic sulphur by which the silver changes its specific nature and turns into gold.201 It was this extraction of tincture that Boyle had enumerated among contingent operations.

199 AdS, PV, 4: 320r. 200 AdS, PV, 4: 324v-325r: “chaque matail a deux sortes de soulphre, I’un interne et generique par lequel son mercure est coagulé et rendu metallique, l’autre est externe et adiousté au premier pour specifier ce corps métallique en tel ou tel metail particulier. Et ce seconde soulphre est dict embryoné & peut estre separé sans la destruction de metail qui demeure corps fusible et malleable, mais son sans la perte de l’estre specifique de tel metail. C’est ce soulphre embryoné qui donnant la specification au subiect generique des metaux, peut aussi causer la transmutation d’un metail desia specifié, s’il est extraict de l’un pour estre appliqué a l’autre.” 201 AdS, PV, 4: 324v-325r.

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Duclos’s insistence on the nature and means of the production of the solvent is significant. Any inconsistencies or contingencies related to this experimental setup are solely attributable to the different qualities of each acid, as forged at the furnace. Whereas a solvent which is the product of a temperate distillation is “purely sulphurated” and hence capable of acting (symbolically) upon the gold’s sulphur to extract the tincture, an acid which has passed through an extreme degree of heat can do little but “corrode the metal and separate between its integrant particles… leaving the constitutive parts in their primary union and in a disposition to regain their original metallic form upon reduction.”202

Following similar Helmontian precepts, then, Duclos exhibited a mélange of vitalism and corpuscularianism in making recourse to both spirits as well as particles.

Duclos’s SER, embodying his particular version of vitalistic corpuscularianism, drew intricately upon sources related in part to the Hermetic, Paracelsian, Helmontian and

Neoplatonic traditions. These, in turn, were embedded in theological motivations informed by a Calvinist-Reformed exegesis of Scriptural Creation coupled with a conviction in a chymical interpretation of the Book of Nature, an outlook that held great currency among the early modern French Paracelsians. Despite his espousal of a self- styled version of corpuscularianism, Duclos’s SER reflected a profound opposition to

Boyle’s mechanical reductionism and his attempt to reconcile mechanical and Christian philosophies by relying upon notions concerning providential design.203 In order to

202 AdS, PV, 4: 326r-326v. 203 Boyle did not defend mechanism despite but rather because of its far reaching religious implications, holding that if the orderly, organized and purposeful universe is nothing more than a vast system of particles in motion, then it can hardly be the result of chance—it must have been designed by a God of exceptional wisdom and providence.

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understand how Duclos’s corpuscularianism and vitalism commingled, we shall inquire into his views of analytic solution chemistry. Chymical analysis was an important research tool in the hands of natural philosophers at the early Academy; it was widely discussed and hotly disputed, especially in the context of the ‘natural history of plants’ project, to which we now turn.

ALKAHEST, CORPUSCLES AND FIRE

In a letter to Colbert in 1666, Christiaan Huygens referred to what would soon become the assembly of members comprising the Academy, established at the end of that year. Huygens referred specifically to the physics or ‘natural philosophy’ faction, suggesting that

the most useful occupation for such an assembly would be to work on a natural history project, modeled on Baconian precepts; a history that would consist of experiments and remarks as a supreme way for attaining knowledge of the causes of all that can be seen in nature; for knowing the causes of gravity (heaviness), heat, cold, attraction, magnetism, light, colors, the composition of air, of water, of fire and of all other bodies; which ascertains animal respiration, the ways metals, stones and plants grow, investigating all things unknown or poorly understood… the method must be one of proceeding from effects to causes… the descriptions should be numerous and detailed.204

204 Huygens, Oeuvres, VI, pp. 95-96 (letter undated): “La principale occupation de cette Assemblée et la plus utile doibt estre, à mon avis, de travailler à l’histoire naturelle à peu pres suivant le dessein de Verulaminus. Cette histoire consiste en expériences et en remarques et est l’unique moyen pour parvenir à la connoissance des causes de tout ce qu’on voit dans la nature. Comme pour sçavoir ce que c’est que la pesanteur, la chaud, le froid, l’attraction de l’aimant, la lumière, le couleurs, de quelles parties est compose l’air, l’eau’ le feu et tout les autres corps, à quoy sert la respiration des animaux, de quelle façon croissent les métaux, les pierres et les herbes, de toutes lesquelles choses on ne sçait encore rien ou très peu… L’utilité d’une telle histoire faite avec fidélité s’estend a tout le genre humain et dans tout les siècles à venir, parce qu’outre le profit

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Although vague about the particular targets of such a broadly defined research program,

Huygens specified that chemistry and the dissection of animals (natural history of animals) should be part of such a project, which, above all else, should first deal with “matters judged good, beneficial and useful.”205

Huygens’s formal proposal helped not only to convince Colbert and his advisers to found the academy but it also seems to have had a substantial influence on the early

Academy’s research orientation. Shortly after the establishment of the Academy, its members became increasingly involved in a prolonged series of animal dissections, ultimately brought together in Claude Perrault’s ‘Comparative Anatomy of Animals’ project, which was published in 1671 as Memoires pour servir a l’histoire naturelle des animaux. Chymical research was even more prominent and was mainly represented by

Duclos and his assistant, Bourdelin. Whereas Duclos’s main contributions were theoretical, Bourdelin, between 1666 and his death in 1699 performed and systematically recorded vast numbers of distillations, mostly of plant matter. Some of Bourdelin’s distillations were commissioned by Duclos for various research purposes, but for the most part they were carried out in the context of the second natural history project of the early

Academy—the natural history of plants—initially proposed by Huygens’s friend, Perrault, in January 1667.206 Perrault distinguished between two types of research required for a comprehensive study of plants: either by collecting plant material and studying its external

qu’on peut tirer des expériences particulières pour bastir une philosophie naturelle, dans laquelle il faut nécessairement procéder de la connaissance des effets à celle des causes. ” 205 Huygens, Oeuvres, VI, pp. 95-96. 206 AdS, PV, 1: 30-38.

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features and medical applications (natural history; l’histoire), or, by conducting an inquiry into the causes of the medical properties of plants and of vegetable reproduction and nutrition (natural philosophy; la physique). The latter way, Perrault thought, would require a broad application of chymical analysis, alongside microscopic observation of seeds and shoots, evaluation of theories of propagation and generation as well as studies of sap circulation, mostly inspired by the question whether sap circulated like blood. Having been suggested as a project only a short while after the establishment of the Academy, the natural history of plants started slowly and on a conservative note, consisting mostly of critical assessments of previously published botanical works (such as Gaspard Bahuin’s

Pinax theatri botanici, which academician botanist Nicholas Marchant had already started to revise).207

Academicians, however, keen to study nature rather than books, undermined

Perrault’s bookish natural history and focused on empirical work, incorporating chymical analyses designed to provide causal explanations to their descriptive matter. This was

Duclos’s main contribution to the project. By June 1668 he delivered a memoir, delineating the method to be applied in the natural history of plants. Perrault’s plan focused on illustrations, which Duclos judged as incomplete, adding the requirement for various textual descriptive details: whether a plant was tall or rested its branches on the ground; whether it sent out roots from these branches; he also demanded precise

207 Stroup (1990), p. 70.

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descriptions of the root, trunk, leaves, flowers, seeds, fruit and other natural products such as resins, gums or liquids.208

Duclos, moreover, added chymical analysis to the work plan. His general scheme consisted of seven major entries concerning the study of plants: “species; differences; denominations; place [provenance]; time [season of growth and maturation]; culture; and uses [medical or other].” Under the heading “differences,” Duclos included “differences which can be gleaned from the plant’s size, its appearance [“port,” carriage], its parts and their products.” As to parts, Duclos specified that, each of the following parts—“stem or trunk, leaves and flowers, fruits or seeds, etc”—must be examined according to “size, number, figure, consistence, color, odor and taste,” followed by an examination of “their constitution.”209 By constitution Duclos meant chymical composition and prescribed, first, the employment of color indicators.210 The second means of analysis would be distillation, followed by a study of the crystals obtained from the coagulated (dried up) juices. Duclos then suggested that “one can finally know the constitution of plants by the qualities of their separated constituent parts, which are their distilled juices (eau distillées), their spirits, both acrid and sulfurous as well as acidic and mercurial, their oils and their fixed or volatile salts.”211

208 AdS, PV, 4: 48r-v: “Il a dict que pour procéder avec méthode en cette histoire, il juge a propos d’expliquer premièrement en peu de mots le portrait de la plante faict par le graveur, on en doibt faire la description exacte claire et succincte. Exacte pour instruire le lecteur de tout ce qui concerne ce subiect. Claire pour ne pas embrasser son esprit de termes ambigus, et succinct pour ne le point fatiguer d’une lecture superflue.” 209 AdS, PV, 4: 48v-49r. 210 Especially noix de galle (oak marble galls, used in the production of dyes; contain large amounts of tannic acid). 211 AdS, PV, 4: 51r.

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Duclos’s consideration of water, acid, oil and salt was in line with commonplace contemporary views regarding the received products of various distillatory fractions. By referring to these distillants or constituent parts as extractions or the end products of extractive processes, however, Duclos implicitly hinted at their status as products of a non- radical or partial separation (recall his view that the Tria Prima are not chymically elementary units). This is further evidenced by his recommendation that “after such extractions, we must proceed to examine each extracted substance.” The examinations implied revolved around the content and characteristics of various salts, typically considered, in traditional seventeenth-century chemical philosophy, as vital-generative constitutive elements.212 For instance, Duclos noted that, “the distilled water of plants that are humid and cold, such as lettuce, purslane or chicory, carries with it some portion of a sulfurous salt.” This salt could be traced when the corresponding distilled water was mixed with a solution of salt of lead, which rendered the solution milky and turbulent. In contrast, the same could not be observed in distilled waters proceeding from dry and earthy plants since their salts were less volatile. Dryness, Duclos suggested, impeded volatility, change and action while fermentation and humidity encouraged vitality, motion and growth. Accordingly, the particular combination of constitutive salts indicated the chymical composition of the plant in question. Similarly, the presence of fixed or alkali salts—typically found in burned plant matter—was ascertained by the dissolution of vitriol

212 See Roos (2007).

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of iron in common water; upon mixing the two liquids, if fixed salts are present, the iron was precipitated, as indicated by the apparent yellowish-reddish color of the solution.213

The significance of the salts as vital-constitutive entities could not be overstated.

Duclos went as far as to propose that,

the various salts of all the constituent parts of a plant can be reunited into one single salt, which will contain all the virtues of that plant. This salt can then be resolved finally into an insipid watery liquid and a pure and dead earth, devoid of all virtue, [and that,] without any notable diminution of weight. This is the extreme [radical] analysis of plants, which serves in acquiring the most exact knowledge of the constitution of a subject.214

This view of what constitutes “the extreme [radical] analysis of plants” echoes Duclos’s

SER and vision of matter, as mentioned before. In line with Van Helmont, Duclos held that a radical chymical resolution, or decomposition, of matter should yield “an insipid watery liquid.” Over the following two weeks, in two consecutive memoirs (dated 16/23

June 1668), Duclos relayed to the assembly his views concerning chymical analysis, pitting distillation against solution analytical chymistry and physical mechanism against organic vitalism, in the context of particulate theories. These memoirs shed crucial light on the way Duclos charted the physical-chymical territory, providing a contextual interpretation of Boyle’s “physico-chymical” program, against the backdrop of contemporary chemical philosophy and Duclos’s SER.

213 AdS, PV, 4: 51v-52v. 214 AdS, PV, 4: 53r-54v: “le divers sels de toutes les parties constitutives d’une plante peuvent estre réunis en un sel, qui contiendra toute la vertu de la plante. Et ce sel peut finalement estre reduict en eau insipide et en terre pure et morte, sans diminution notable de son poids. Et cela est l’extreme analyse de la plante.”

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Duclos’s decision to dedicate two consecutive meetings to the theoretical aspects of chymical practice is telling, especially in light of the early Academy’s pronounced empirical-Baconian agenda, upheld in an attempt to minimize debate among members of a new and variegated collective research enterprise. The informal reason behind Duclos’s decision was clearly linked to the research agenda he was interested in promoting for the project on the natural history of plants. By 1668, given the prominence of chymical research and analysis, Duclos was presiding over that project. The official excuse, however, is found at the beginning of the first memoir, dedicated to fire analysis

(distillation):

Mr. Duclos has said that, lacking a laboratory for conducting chymical analyses, and wishing to avoid idleness, while all other members of the company are busy working, he had made up his mind to propose to the assembly, to render advice as to the methods for performing chymical analyses, which will be useful once a laboratory is established; having received the company’s approval, he went on to claim that the principle means of analysis are fire, air and dissolutive liquors.215

Opening the first memoir, the last statement in this passage sets the background to the ensuing discussion. Fire, Duclos noted, acts to separate (decompose) the parts of a mixt in two ways: either by the action of its heat alone, in which case no inflammation occurs, or

215 AdS, PV, 4: 58r: “Mr du Clos a dict que n’ayant point encore de laboratoire pour travailler aux analyses chimiques, et ne voulant pa d’ailleurs demeurer oisif, pendant que toute le monde de la compaignie travailloit chacun de son coste, il avoit jugé a propos de proposer a l’assemblée la metode qu’il seroit d’advis qu’on observant pour procéder a ces analises lors qu’on aura un laboratoire ; et la compagnie ayant approuvée sa proposition, il dit qu les pricipaux moyens des analyses chimiques sont le feu, l’air, et les liqueurs dissolutives.”

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by way of combustion and inflammation.216 Duclos explained the mechanism underlying fire analysis—or distillation—in the following manner:

The heat of the fire excites a motion in the mobile parts [of the mixt], according to their degree of mobility, to the effect that those that share the same degree of mobility cannot separate at the same degree of heat, which in agitating them equally, makes them rise together, and [hence] they separate only from the [relatively] less mobile parts. And those that are unequally mobile separate from each other, because the easiest to move [most prone to motion and excitability], being most agitated and most rapidly rarified by the heat, rise first and detach from the less mobile, that can follow when chased by a stronger fire.217

This explains at once how distillation works to separate constituents of mixts and signals the limitations of fire as an analytical tool; it implies that two constituents can be different yet by virtue of sharing the same degree of mobility (excitability), will not be separated during distillation, as the fire will cause “them [to] rise together.”

Duclos underscored the relation between heat and motion by challenging “those who say that it is a property of heat to bring together things of the same nature and to separate those of various natures.” This signals Duclos’s critique of traditional Scholastic and Paracelsian precepts according to which like acts upon like, as applied to distillation practices. In effect, it is not the heat that actively separates or unites the constituents of bodies, for its sole action is to impart motion, according to the given constituents’ degrees

216 AdS, PV, 4: 58r-v: “Pour ce qui est du feu il agit dans la séparation des parties des mixtes ou par sa chaleur seule sans embrassement ou par embrassement et combustion.” 217 AdS, PV, 4: 58v: “La chaleur du feu excite du mouvement dans les matières mobiles, selon le degré de leur mobilité, de sorte que celle qui sont mobiles en mesme degré ne se séparent point les unes des autres par un mesme degré de chaleur, qui les agitant également les fait monter ensemble, et les sépare seulement de celles qui sont moins mobiles. Et celles qui sont inégalement mobiles se séparent les unes des autres, car les plus faciles a se mouvoir estant plus agitées et plus tost raréfiées par la chaleur s’eslevent les premières et quittent celles qui sont moins moniles mais qui les peuvent suivre estant pressées d’une chaleur plus forte.”

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of mobility. The subsequent separations or unions are consequences of the motion—which depends upon the constituents’ propensity to move—not of heat in itself. Duclos’s discussion of possible unions suggests yet another sense in which he was critical of the analytical capacity of fire, for some constituents will “only liquefy and attach to those which are fixed, producing a new composition of parts.”218 Significantly, Duclos avoided interpreting such unions by recourse to affinity, resemblance or correspondences (whether occult or not) acting between two entities that bear essential similarities. In line with his

SER, he allowed for only the physico-mechanical principle of motion in explaining the separation as well as creation of new compounds during distillation, which again, is proven as an incomplete and partial means of resolution. Yet even more significant is the fact that

Duclos, in a fashion much like Boyle’s critique of fire analysis (especially in his Sceptical

Chymist), suggested that fire may alter the components. Not only did fire fail to decompose mixts into their constituent elementary parts, it created new ones that were not initially part of the analyzed mixt.219

Closely acquainted with chymical experimental reality, Duclos admitted that, “fire can occasion, by the power of its heat, not only separation, but also union.” Herein, then, lies the explanation of volatility or fixity of chemical substances, since fire

separates the volatile parts from the fixed ones by the motion occasioned by its heat… and it causes the union, into a new compound, of the parts which are less fixed with those that are more fixed, melting and liquefying the

218 AdS, PV: 4, 59r-v. 219 For details on the controversial nature of fire analysis in the early modern period see: Debus (1967); Holmes (1971).

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humid parts which penetrate into the dry ones, combining together, as in the case of carbon and glass.220

Heat, however, can produce some unions that will resist all degrees of heat; such unions can be resolved only by means of “inflammation and combustion.” The latter necessitate the presence of air and hence mark the limited capacities of distillation, which customarily takes place “in closed vessels” joined and “sealed carefully.” By means of its heat and inflammation, fire can resolve “mixts that [were] composed of volatile or combustible parts.” For the analysis of the most fixed (immobile, non-volatile) mixts—those that are usually earthy and dry, since fixity is related to lack of humidity—Duclos prescribed the use of “resolutive menstrua.”221

At the beginning of the following memoir, dedicated to solution analysis, Duclos provided a crucial clue regarding the mechanism of action of such solvents:

since most mixts that do not have a strong compaction between their parts, are independently resolved [resolve themselves] by way of putrefaction in their own humidity, the chymists have taken the opportunity to conduct the resolution of less humid substances by way of putrefaction, by the addition of some regulative liquor.222

These are commonly referred to as “regulative” liquors and their function is to

“facilitate putrefaction” or fermentation. Duclos distinguished between three kinds of

220 AdS, PV, 4: 60r: “fait séparer les parties volatiles des fixes par la mouvement que sa chaleur… et il fait coniondre en un composé nouveau les matières qui sont moins fixes avec les plus fixes, fondant et liquefiant les humides qui pénètrent dans les seiches et sentient avec elles, comme il se fait au charbon et au verre.” 221 AdS, PV, 4: 60r-61v. 222 AdS, PV, 4: 63v-64r: “Parce que la plus part des mixtes qui n’ont pas une forte componction de leus parties, se résolvent d’eux mesmes par la putréfaction en leur propre humidité ; Les chymistes ont prins de la occasion de faire des résolutions des metieres moins humides par putréfaction a l’aide de quelque liqueur adioustée [ajustée].”

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menstrua, solvents, or regulative liquors: corrosive, extractive and resolutive. The corrosive, when applied to solid mixts, brings about the discontinuation of their mass and break them down into “integrant, highly subtle, particles”; the extractive is employed for the extraction of a certain part of the mixt (usually acts by precipitation); and the resolutive is used for occasioning a “radical resolution.”223 Duclos referred to the latter in his research proposal for plant analysis as the “extreme analysis of plants, which serves for acquiring the most exact knowledge of the constitution of a subject.”224 This type of resolution, moreover, was highly regarded and sought after in analytical chymistry; according to Duclos, the resolutive menstrua and their actions should be studied most closely. The corrosive resolution, on the other hand, is considered as a preparatory step to the extreme resolution in that it rarifies the parts of the mixt and endows them with a kind of heightened activity and enhanced mobility, making them less compact.

All these menstrua, Duclos proclaimed, consist of “salts, resolved and spiritualized,” that is, “reduced into highly penetrating liquors.” These salts are either mercurial, sulfurous or mixt. The mercurial liquors are acidic and merely corrosive (like aqua fortis) while the liquors of sulfurous salts are acrid and merely extractive (like spirit of wine or alcohol). The mixt spirits, containing both mercurial and sulfurous salts, joined together, are solely capable of occasioning a radical resolution: “these mixt menstrua are the true solvents, intended for real chymical analyses… they are useful in the research of the principles of natural mixts as well as in performing analytical observations, which

223 AdS, PV, 4: 64r-v. 224 AdS, PV, 4: 53v.

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facilitate our knowledge of the nature and qualities of mixts.”225 The radical resolutive analysis, then, is an organic-vital process. Its activity generated by the combination of mercurial and sulfurous salts, it is analogous, like other types of resolution, to putrefaction and fermentative processes.

By 1668, when Duclos expounded his SER in the context of his views on chymical solution analysis and argued for its relevance to plant analysis—a matter that had been recognized by the assembly—a basic framework for the natural history of plants existed.

To some extent, the plan was multi-authored, drawing on an accumulation of ideas and proposals by Huygens, Perrault and Duclos. For carrying out the actual research, however, the Academy depended almost entirely on Bourdelin to analyze plants in the laboratory and on the botanists Nicolas and Jean Marchant to cultivate and describe them. Duclos’s assistant, Bourdelin, refined chemical techniques, especially for analyzing oils, and kept detailed records of his experiments and laboratory expenses.226 The Marchants, father and son, who cultivated rare plants for the Academy's use, were in charge of sections of the

Royal Gardens, nurseries and the orangerie; they cultivated seeds from all over the world, collected by friends, acquaintances, and colleagues. After cultivating a plant, the

Marchants described it, gave it to the illustrators and supplied the rest to Bourdelin for analysis, which often required very large quantities of plant material.227

The ambitious ‘natural history of plants’ collective project went down in the chronicles of the Academy as an overall failure: despite efforts to minimize controversy, it

225 AdS, PV, 4: 64v-65v. 226 MS. n. a. fr. 5147. 227 On Nicolas and Jean Marchant see Laissus & Monseigny (1969) and Sturdy (1995), passim.

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was plagued by numerous disputes between academicians over theory as well as practice and was never completed or published as intended. Almost a decade after it was first proposed by Perrault and subsequently expanded by Duclos, in 1676, two publications appeared, drawing on the vast work carried out under the banner of this project:

Marchant’s Descriptions de quelques plantes nouvelles and Denis Dodart’s Mémoires pour servir a l’histoire des plantes. True to its title, Marchant’s Descriptions consisted mostly of a descriptive history of plants, displaying illustrations while lacking reference to plant analysis; Dodart’s Mémoires, in contrast, discussed chymical analysis at length. Dodart, however, advanced a different view of the subject than the one envisioned by Duclos, the initial director of the project.

Since 1671, the year Dodart joined the Academy, Duclos’s power over the project as well as his status within the Academy had been increasingly undermined.228 Dodart was about 35 years younger than Duclos, who was 68 years old when he had initially joined the

Academy in 1666. Dodart was ambitious and energetic and soon after joining the

Academy took over the ‘natural history of plants’, marginalizing Duclos.229 The decline of

Duclos’s institutional power cannot be attributed to one single reason but the most prominent factor in his demise arose from his research agenda, and especially his promotion of solution analysis alongside (but mostly over and above) distillation. The minutes of the Academy chart this decline. During the late 1660s, Duclos was by far the

228 On Duclos’s decline see Stroup, Kim (2003), pp. 51-52. MS. n. a. f. 5147 charts Duclos’s decline by showing how during the 1670s and 1680s he had placed increasingly fewer laboratory orders while Dodart had taken over, his name being increasingly associated with the laboratory working transactions, requests and expenses (all recorded and tabulated by Bourdelin). 229 On Dodart and the various research tensions in the ‘natural history of plants’ project see Holmes (2004), esp. pp. 277-288.

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most active academician; between 1667 and 1669 his memoirs fill roughly 500 pages of the procès-verbaux, discussing chymical analysis, coagulation and cohesion, as well as providing a detailed scrutiny of Boyle’s Certain Physiological Essays and The Origin of

Forms and Qualities; from 1675 to 1683 his memoirs barely fill 20 odd pages.

Dodart was Perrault’s protégé and both shared, to different extents and in different fashions, mechanistic views. Duclos, in his SER, especially as seen in his views on chymical analysis, did not reject mechanistic principles; he even upheld a version of chymical corpuscularianism, mentioning particles under the influence of motion. Yet he drew a clear and distinct line between the mechanical and the chymical, arguing that physical reactions (i.e. mechanical) were superficial: distillation, being based on separation by heat according to degrees of mobility, was an incomplete method for decomposition, a partial analytical tool. In contrast, solution analysis, based on essentially vital and fermentative processes, represented chymical deep-level resolution. By way of analogy, physico-mechanical decomposition processes, such as separation by heat, were the opposite of mixtion, physical combination, or aggregation of constituents; chymico-vital resolutive processes, such as the ones generated by “true solvents” were the opposite of generation. Such notions can be traced back in time to Paracelsian and especially

Helmontian doctrines, closely identified with alchemical, Platonic and Hermetic precepts, all of which were controversial, particularly during the 1670s-1680s. At the same time, as we shall see, similar notions and distinctions can be found in eighteenth-century chemistry and matter theory. The young Academy, hosting members from a wide variety of backgrounds, dependent on royal funding for its existence, preferred to distance itself from any apparently subversive views associated with natural magic, Platonism or occultism.

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In his second memoir on chymical analysis, treating resolutive menstrua, Duclos observed that such “menstrua are either universal or particular. The universal [ones] must originate from the less specific salts, of a mixt and tempered nature. Such is the salt out of which Paracelsus produced his great solvent [Paracelsus’s Alkahest], which he named Sel

Circulé.”230 Only two months later, in August 1668, Duclos discussed at length this

Paracelsian salt, alongside Van Helmont’s Alkahest, the utopian universal solvent, presenting the assembly with a detailed survey and interpretation of alchemical literature concerning menstrua and seminal principles.231 Duclos repeatedly drew the distinction between vulgar (distillatory, mechanical, physical) and philosophical (vegetal, chymical, transformative) practices. Newton, as we shall see, displayed similar intimations in his alchemical tracts, in the 1713 General Scholium as well as in his Opticks.

In this sense Bourdelin was a vulgar chymist, a lifelong supporter of distillation analysis, a practice he dogmatically refused to abandon, performing for the academy thousands of distillations until his death fourteen years after Duclos’s. The task of interpreting Bourdelin’s results fell first on Duclos and then on Dodart. The wealth of records and information was immense, involving for example the weight of distillants, temperature records, colors, tastes, odors, color reactors, alongside a wide range of

230 AdS, PV, 4: 65v: “Les menstrües sont ou universels, ou particuliers. Les universels doivent estre tirez des sels les moins spécifiez, mais de nature mixte et tempérée. Tel est le sel commun, duquel Paraclese a fait son grand dissolvant, qu’il nomme Sel Circulé.” 231 Duclos delivered two lengthy and detailed memoirs on the subject of solution chymistry and the alkahest (18/15 August 1668). See AdS, PV, 4: 134r-175r. Paracelsus and Van Helmont are mentioned more than anyone else, followed by a discussion of Deiconti’s solvent; Glauber, Duchesne and Trismosin are mentioned too. On salts in the Paracelsian and Helmontian contexts see, for instance, Roos (2007), pp. 10-107. For an introductory historical study of alkahest see Reti (1968); for an interesting exploration of the relation between alkahest and chymical theory in he second half of the seventeenth-century see Joly (1996).

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distillation techniques based on the consequent replacements of recipients for each fraction, or practicing heat control by employing a double boiler. This superfluity of data left academicians, and especially Dodart, puzzled. Nonetheless, the Academy remained largely committed to distillation throughout the rest of the seventeenth-century. Duclos did not live to see the application of his visionary ideas concerning the analytical chymistry of solutions.232

Distillation, or fire analysis, was challenged as a legitimate means for the extraction of elementary constituents. But while research into the ultimate principles of mixts had been mostly Duclos’s aim (and in this respect he may be seen as more interested in natural philosophy than natural history), Dodart was interested in the medical uses of plants and in their nutritive values and mechanisms. This is not to say that Dodart had no qualms about distillation, which he had to scrupulously defend in his Mémoires. On the defensive and forced to support increasingly untenable arguments he still remained committed to fire analysis. In his 1676 Mémoires, more than half of which had to be dedicated to justifying the shortcomings and inaccuracies of fire distillation, Dodart stated clearly why the alternative, long since promoted by Duclos, was inappropriate: “for knowing that which plants are, we do not have to make the great efforts of resolving them into that which the chymists call their primary principles; that is, to irreversibly resolve them into a simple solution, containing their virtues, by means of allegedly universal solvents, enigmatically described by Paracelsus, Van Helmont, Deiconti, etc.”233 This reference is unmistakable:

232 Shortly after Bourdelin’s death Simon Bouldoc proposed the use of solution over distillation analysis. Kim (2003), p. 79. 233 Dodart (1676), p.13.

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these three chymical authors comprised the main subject matter of Duclos’s 1668 discussions of the Sel Circulé, alkahest and universal solvents.234

Dodart proceeded to dismiss any such ideas, claiming that, “these solvents are found only in books.” He noted, furthermore, that it would probably be more difficult to grasp the nature of these solvents than the nature of the plants themselves.235 With this view in mind, judging such chymical perceptions so harshly, Dodart struggled to find ways to compensate for the deficiencies of fire analysis, undermining its empirically inaccurate and controversial nature while arguing for the inadequacy of chymistry (in the Duclosian sense) for the pursuit of natural knowledge. This was a far cry from Huygens’s early vision of a natural history providing a “supreme way for attaining knowledge of [natural] causes,” or of Duclos’s similar allusions; instead, Dodart advanced a methodologically convoluted and epistemologically impoverished discourse, bordering on simplistic skepticism, as can be gleaned from the following passage, part of his concluding remarks on “general reflections” on all chymical analyses in the study of plants, solution and distillation:

it is not completely impossible to arrive, by the [chymical] analysis, at a certain degree of knowledge, which may serve at least for forming some conjectures, reasonable enough to be examined, and possibly incorporated in physics, almost as ordinary descriptions… 2. that it is very difficult, not to say impossible, to attain by analysis an accurate and certain knowledge of the natural constitution of each plant; 3. that in employing chymistry, we do not actually engage in the pursuit of the principles of natural mixts, or as the chymists call them simple and inalterable… It is not that we do not seek greater certitude, but we believe that we must stay within these limits, hoping that more reasonable [capable] persons, well aware of the great difficulties in attaining the knowledge of the simpler things, and who know

234 AdS, PV, 4: 128r-175r. 235 Dodart (1676), p.13.

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that even the possession of such knowledge will not remove all difficulties, will be content with what we have to offer… chymical inquiries which one day, we hope, will be employed as the basis for reasonable, even if not certain, conjectures.236

Dodart’s disillusionment with chymical analysis is evident. With efficient solvents “found only in books” he accorded distillation a “certain” degree of legitimacy. As problematic as it was, Dodart still considered it as the most appropriate means of analyzing plants.

Duclos’s critique of distillation processes notwithstanding, his chymical SER suggests, first and foremost, the significance of the distinction between the physical-mechanical and the chymical-vital (or chymical-generative and vegetative). As we have seen, this dimension of his SER dominated his interpretation of chymical analysis, a theme tightly linked to his vision of matter, elements and material change. The distinction between the chymical and the physical, in the institutional context of the early Academy, is thrown into final relief in the debate over pesanteur between chymically- and physically-minded academicians. This debate, aspects of which I discuss next, was prompted by Duclos’s critique of the final section of Boyle’s Physiological Essays.

236 Dodart (1676), pp. 14, 17: “qu’il ne pas évidement impossible de parvenir par l’analyse à un certain degré de connoissance, qui pourra servir au moins à former des conjectures assez raisonnables pour estre examinées, & peut-estre receuës en Physique, à peut prés comme les descriptions ordinaires… 2. qu’il est fort difficile, pour ne pas dire impossible, de tirer de l’analyse une connoissance sance precise & certaine de la constitution naturelle de chaque Plante ; 3. que nous servant de la Chymie, nous ne nous engageons ny à recevoir les principes des corps naturels, selon les Chymistes, comme principes, c’est à dire, comme généraux, ny comme simples, ny comme inaltérables… Ce n’est pas que nous ne desieassions une plus grande certitude, mais nous croyons devoir demeurer dans ces bornes, & nous espérons que les personés équitables, & qui sçavent combien les moindres choses sont difficiles à connoistre, & combien en a connu, nonobstant tout les difficultez, se contenteront de ce que nous pouvons leur promettre… la Chymie les recherches sur lesquelles on peut espérer de fonder un jour quelques conjectures raisonnable, encore qu’on ne s’y puisse promettre une entière certitude.”; italics added.

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FROM COHESION TO PESANTEUR

The Saturday meeting of 19 January 1669 marks the beginning of Duclos’s examination of the second and final section of the second half of the Physiological Essays:

The History of Fluidity and Firmness. Duclos dedicated two consecutive memoirs (19 and

26 January) to discussing fluidity and one memoir, delivered on 23 February, to the causes of solidity, cohesion or “firmness”; the latter memoir is the last of thirteen in the series comprising Duclos’s scrutiny of Boyle’s Physiological Essays. Boyle opened by declaring that the “following Particulars touching Fluidity and Firmness were first written but by way of Annotations” upon the former “Essay on Salt-Petre”; hence, “the unaccurateness of the Method, as a fault scarce evitable on the occasion.” As to the content, Boyle claimed to have but “set down Experiments and other matters of fact related to the Subjects,” humbly inviting “abler Pens to contribute their Observations towards the compleating of what he is sensible he has but begun.”237 Perhaps perceiving himself as an “abler Pen,” in contrast to Boyle’s pretensions to diffidence, Duclos openly rendered his overall judgment of the treatise:

The history of fluidity and solidity, comprising the second treatise of this second part of Boyle’s book of essays, is presented as an imperfect and prudent draft, in order to make excusable that which is found less explicable and less consistent according to the atomic or corpuscular doctrine, which Mr. Boyle perhaps could not find as easy to establish upon chymical experiments as he would wish to suggest.238

This critique, delivered in the beginning of 1669, triggered a lengthy series of implicit and explicit contentions over the nature of micro- and macro-matter within the Academy.

237 Boyle, CPE, p. 117. 238 AdS, PV, 6: 14r.

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These tensions, aspects of which comprise the subject of the following discussion, climaxed around nine months later.

In the summer of 1669, seven senior members of the Academy debated the causes of terrestrial gravity (causes de la pesanteur). During the same summer at least four academicians participated in a debate over the causes of coagulation.239 Both controversies consisted in exchanges of memoirs, delivered at the traditional weekly conventions (the mathematicians met on Wednesdays; the natural philosophers on Saturdays). The controversy on gravity lasted from August until late November and saw contributions from five mathematicians and two natural philosophers. The debate on coagulation, which peaked in the summer, lasted nearly a year and encompassed a prolonged collective experimental program, attributed in the procès-verbaux to the “company” alongside individual contributions from Huygens (mathematician), Edme Mariotte, Claude Perrault

(naturalists) and Duclos. The two debates overlapped chronologically as well as thematically and included Huygens, Mariotte and Perrault as participants.240

On 7 August, the mathematician Gille Personne de Roberval raised the question concerning the possible causes of gravity.241 His introduction was followed by the memoirs of two other mathematicians, Bernard Frenicle de Bessy and Jacques Buot. On

28 August, Huygens relayed his theory of gravity in a lengthy account, which formed the

239 The participants in the debate on gravity, in chronological order of memoirs delivered, were Gilles Personne de Roberval (7 August & 4 September), Bernard Frénicle de Bessy (14 August), Jacques Buot (21 August), Christiaan Huygens (28 August & 23 October), Edme Mariotte (4 September & 13 November), Jean-Baptiste Du Hamel (6 November) and Claude Perrault (20 November); individual participants in the debate on coagulation included Duclos (9 March?, 27 April, 1 June, 6 & 13 July, 14 December), Mariotte (20 July), Huygens (3 August), Perrault (undated). 240 On Mariotte see Costabel (1986); on Perrault see Picon (1988). 241 On Roberval see Auger (1962).

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blueprint to his Treatise on the Causes of Gravity, published in 1690 as an appendix to his treatise on light.242 The following week, in a joint memoir, Roberval and Mariotte raised a series of objections to Huygens’s views, to which the latter replied on 23 October, followed by contributions, in November, by Jean-Baptiste Duhamel, Mariotte and Perrault.

The debate on gravity turned out, to a substantial extent, into a discussion of Huygens’s theory, with the tripartite Roberval-Mariotte-Huygens exchange forming the controversy’s centerpiece.

Introducing the issue, Roberval defined the gravity of a body as that which carries it naturally, without artificial aid, downward toward a center; one can thus consider, he suggested, “terrestrial, lunar, solar or jovial” gravities. Roberval distinguished between conceptions of gravity as a primary cause of motion and the idea that gravity is a consequence of motion. As a primary cause, it might be either a quality inherent only in heavy bodies or it might be a common and reciprocal attractive relationship between them.

Alternatively, according to mechanistic views, motion causally precedes gravity, which is brought about by a third entity, usually a fast-moving subtle matter (ether, or “corp très subtile”).243 Although Roberval remained agnostic with respect to the ultimate cause of gravity, he considered the notion of reciprocal attraction as most probable. From the standpoint of the relationship between matter and activity, Roberval seems to have

242 Huygens (1690). 243 Huygens, Oeuvres, XIX, p. 626: “J’appelle la pesanteur d’un corps ce qui porte ce corps a descendre vers un centre par la nature seule et sans artifice. Ainsi, on pourra considérer une pesanteur terrestre, une lunaire, une solaire, une joviale, etc… ceux de la troisième [opinion] ont d’ordinaire recours a quelque corps très subtil qui se meut d’un mouvement très viste et qui s’insinue facilement entre les parties des autres corps plus grossiers, de sorte qu’en les pressant, il les pousse vers le bas ou vers le haut : et par ce moyen ils sont la pesanteur ou la légèreté.” (Roberval’s memoir, 7 August 1669).

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subscribed to the view that matter is not essentially active in and of itself, and he viewed gravity as a distinct principle, though not necessarily physically separate. This stands in contrast to the scholastic notion of gravity as an intrinsic quality common to all heavy bodies.

A devout mechanist, in a distinct Cartesian vein, Huygens was the spokesman for the third alternative, according to which matter is completely inert, passive and devoid of inner activity. In terms that remind us of Boyle’s epistemological stance, Huygens claimed that an intelligible explanation of gravity must include nothing but matter and motion, a framework he referred to as the only possible “true and sound philosophy.”244 Huygens’s theory of gravity was a corrective variant of the Cartesian speculative hypothesis of the vortex. The tendency of bodies to fall was accordingly the consequence of an extraneous action, attributed to a matière fluide or matière céleste consisting of tiny, rapidly moving particles, which fill the space around the earth. The subtle matter—by definition the subtlest of all matter and hence able to pass unhindered through the pores of all material bodies—forms a whirlwind around the earth. Influenced by the centrifugal tendency, the gravitational fluid is thrown back at the outer borders of the vortex, where it concentrates.

Any coarser bodies found among the fast moving gravitational particles, unable to keep up with the same speed, will be pressed down towards the center of the earth. To wit, the greater centrifugal tendency of the subtle matter propels the coarser bodies centripetally.

Roberval, Mariotte and Frenicle favored, by and large, the dynamical explanation, considering gravity as a natural inclination, a quality causing material parts to join

244 Snelders (1989), p. 212.

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together. Huygens, Perrault and Buot defended the kinematic-mechanical view, interpreting gravity by recourse to versions of kinematic corpuscularianism and speculative particulate theories. Huygens, in line with late seventeenth-century proponents of mechanical explanations, highlighted intelligibility. “To find an intelligible cause of gravity,” he suggested, “it is necessary to see how it can be done while postulating in nature only bodies made of the same matter, in which no quality is considered, nor any inclination for each to approach the others, but only different sizes, shapes, and motions.”245 In their joint memoir Roberval and Mariotte charged Huygens for excluding out of nature, “without proof, attractive and expulsive qualities” and for introducing,

“without foundation, the sole sizes, figures and motion of particles.” They further pointed out the circularity of Huygens’s argument: motion cannot be the sole cause of motion. In search for true causality, such a premise would require the inclusion of a primary cause, which would have to be “as incomprehensible as qualities, if not more so.”246 To which

Huygens replied, in a spirit not unlike the one found in Newton’s Principia, regarding the cause of forces that, “we know with certainty that moving bodies are capable of imparting motion to other… and that is all I need, without searching here by which cause the primary motion has been introduced.” Huygens, in other words, rejected the search for a primary

245 Huygens in Dear (2001), p. 151; italics added. Huygens wrote in his memoir dated 28 August 1669: “Pour chercher une cause intelligible de la pesanteur il faut voir comment il se peut faire, en ne supposant dans la nature que des corps faicts d’une mesme matière, dans lesquels on ne considère nulle qualité, ny inclination a s’approcher les uns des autres, mais seulement des différentes grandeurs, figures et mouvements.” Huygens, Oeuvres, XIX, p. 631. 246 Huygens, Oeuvres, XIX, pp. 640-641. Huygens “veut qu’un mouvement soit causé par une autre mouvement, il faut donc venir a un premier qui est autant ou plus difficile a comprendre que les qualitez. Ne pouvant arriver a un premier mouvement par le mouvement mesme il en faut venir aux qualitez ou a une autre cause équivalente, et le mouvements qui en dépendront ne peuvent ester les siens comme il se verra cy après.”

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cause, limiting the scope of his inquiry to intelligible causal explanations. But Roberval and Mariotte insisted in showing how Huygens could not avoid recourse to qualities.

Huygens’s alleged subtle matter is endowed with circular motion, yet circular motion is in fact only a particular case of rectilinear motion coupled with the influence of an additional quality: circular motion is but a consequence of the rectilinear motion and hence cannot be

“natural” in this respect. Huygens’s response was: “I never claimed that circular motion is natural, but only that it exists in the world, which is an indubitable fact.”247

This exchange of opinions represents aspects of contemporary dissatisfaction with the mechanistic reductive enterprise.248 The controversy on the causes of gravity—at the confluence of kinematics, dynamics and metaphysics—is a relatively well-known episode.249 Less known is the debate on the causes of coagulation and cohesion, which was sparked by Duclos’s reading of Boyle’s History of Fluidity and Firmness.

Considering the two controversies as treating aspects of macro- and micro-matter, of physics and chymistry, of mechanism and vitalism, respectively, their examination affords valuable insights into the chymical SER during the Scientific Revolution.

Newton had grappled throughout his career with the question concerning the relation between long and short-range action. In the 28th query of the his Opticks (4th ed.;

1730) he commended the ancient natural philosophers, who “made a Vacuum, and Atoms, and the Gravity of Atoms, the first Principles of their Philosophy; tacitly attributing

247 Huygens, Oeuvres, XIX, pp. 641-643. 248 For an insightful analysis concerning epistemological difficulties related to the mechanical philosophy see Gabbey (1985), esp. pp. 28-38. 249 See, for example, Mouy (1934), pp. 187-192; Dijksterhuis (1961), passim.

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Gravity to some other Cause than dense Matter.” Much in line with the critique Roberval and Mariotte leveled against Huygens in 1669, Newton complained that,

Later Philosophers banish the Considerations of such a Cause out of natural Philosophy, feigning Hypotheses for explaining all things mechanically, and referring other Causes to Metaphysics: Whereas the main Business of natural Philosophy is to argue from Phaenomena without feigning Hypotheses, and to deduce Causes from Effects, till we come to the very first Cause, which certainly is not mechanical.250

By the 1720s, the last decade of his life, Newton felt more at ease in considering radical mechanistic agendas, such as the one expounded by Huygens, as hypothetical. In his controversial General Scholium of 1713 we find Newton presenting an argument from design, suggesting that, “Blind metaphysical necessity, which is certainly the same always and every where, could produce no variety of things.” Newton’s distinction between sameness and variety is significant. The far-reaching religious dimensions of the Scholium notwithstanding, it is clear that Newton grew disaffected with pure mechanical philosophy not only because of its theological implications but also from a metaphysical perspective.

The opening statement of the Scholium bears witness to this inclination: “The hypothesis of Vortices is press’d with many difficulties,” whereby Cartesian vortical theory and

Descartes’s method are signaled by “Vortices” and “hypothesis,” respectively. 251

Having admitted his failure “to discover the cause of those properties of gravity from phaenomena,” Newton proceeded to stress the empirical (phenomenal) reality of gravity: “it is enough, that gravity does really exist, and act according to the laws which we

250 Newton (1952), p. 369. 251 Newton (1729), II, pp. 387, 391; italics added. Newton’s use of “hypothesis” is important and can be linked to his frontal attack on Descartes’s hypothetico-deductive method (found in the fifth paragraph of the Scholium).

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have explained, and abundantly serves to account for all the motions of the celestial bodies, and of our sea.” Unlike Descartes, for whom God’s existence was axiomatic,

Newton wished to induce God from nature. Yet he was equally interested in understanding

God’s agent in nature, the proximate cause for nature’s great variety, life and activity.

Newton speculated on this cause, suggesting the action of

a certain most subtle Spirit, which pervades and lies hid in all gross bodies; by the force and action of which Spirit, the particles of bodies mutually attract one another at near distances, and cohere, if contiguous; and electric bodies operate to greater distances, as well as repelling as attracting the neighboring corpuscles; and light is emitted… and heats bodies; and all sensation is excited, and the members of animal bodies move at the command of the will.252

Newton distinguished between “gross bodies” and the “subtle spirit,” as the cause of cohesion and short-range attraction.253 Accordingly, intra-corpuscular attraction is closely related to vitality in nature.254 As Newton pointed out in the early 1670s, in one of his alchemical tracts: “Nature’s actions are either vegetable or purely mechanicall.” The mechanical was for Newton exemplified by “operations of the vulgar chemistry… as strange transmutations as those of nature… that are but mechanicall coalitions or seperations of particles as may appear in that they returne into their former natures if

252 Newton (1729), II, pp. 392-393. 253 On Newton’s views on matter and activity see McMullin (1978). 254 This is a highly complex issue. Most mechanical philosophers subscribed to a view according to which matter was inert and devoid of inner activity. In the alchemical and chymical traditions, the phenomena of cohesion and coagulation were closely related to processes of generation, fermentation and putrefaction. In both cases, the question was what activates matter and how. Mechanical explanations tended to deal with this material ‘vitality’ by recourse to naturalistic explanations, avoiding appeal to supernatural notions. For an original and insightful study on this subject see Hutchison (1983). In the alchemical tradition, vitalism and matter were often connected through the concept of ‘semina’, seeds, seminal principles or archeus. On this subject see the authoritative recent study Hirai (2005). See also Henry (1986).

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reconjoned or (when unequally volatile) dissevered, & that without any vegetation.”

Newton then added:

So far therefore as the same changes may bee wrought by the slight mutation of the textures of bodies in common chymistry & such like experiments may judge that such changes made by nature are done the same way that is by the sleighty transpositions of the grosser corpuscles, for upon their disposition only sensible qualities depend. But so far as by vegetation such changes are wrought as cannot be done without it, we must have recourse to some further cause. And this difference is vast & fundamental because nothing could ever yet be made without vegetation which nature useth to produce by it.255

This contrast, drawn by Newton between the “mechanicall” and the vegetal realms on the one hand, and the corresponding practices of “vulgar” and ‘philosophical’ chymistry on the other, was at the heart of the Academy’s debate over coagulation.

Although the debate climaxed during the months of July and August 1669, when most of the theoretical summaries were presented, the Academy’s interest in coagulation and cohesion goes back to the beginning of the year, when Duclos delivered his lecture- demonstrations dealing with Boyle’s views on Fluidity and Firmnesse. In March and

April 1669 Duclos introduced the subject—causes de la coagulation—providing chymical interpretations and accounts.256 This prompted a wide interest among the members of the

‘philosophical’ group who, between April and July, carried out a prolonged series of related experiments. Leading experimental themes included the coagulation of milk, of egg white, and of blood, both venous and arterial; two vivisections were performed and the pericardial fluids found in a horse’s heart were analyzed. Much of this experimental

255 Dibner Collection, MS 1031b, 5r-v. 256 AdS, PV, 6: 60r-67r; 108r-117v; 199r-206r.

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endeavor was conducted collectively and respective Mémoires were assigned to the

“company” alongside individual contributions.257

The controversy on coagulation takes us deeper into the world of micro matter and the relations between macro phenomena and perceptions of the micro-particulate realm. A thoroughgoing mechanist, Huygens attempted to penetrate the domain of micro matter with the same tools and categories he had employed in his account of terrestrial gravity, highlighting, above all else, epistemological intelligibility. For Boyle, the chymical mechanist, fluidity depended upon three principles. First, the corpuscles must be small, round and smooth; second, their disposition must be such as to leave empty spaces between them, so as to enable their motion; third, and most important according to Boyle, the corpuscles must be all separately agitated and independently endowed with motion,

“whether by their own innate and inherent motion, or by some thinner substance that tumbles them about in its passage through them.”258 A liquid, then, consists of small, round and smooth particles that constantly move, vibrate and exchange places in space.

For Huygens, “coagulation produced consistent matter out of liquid.” “I believe,” he noted, “that for examining the cause of coagulation, we must first find out what comprises a liquid and what comprises a solid [consistent matter].” As we might expect, his definition of a liquid depended upon the detachment of corpuscles and their perpetual motion. Arguing for the necessity of motion, Huygens proposed that the natural tendency of liquids to form flat surfaces (finding the lowest resting place possible) could not be

257 Memoirs assigned collectively to the “company” were delivered on 4, 11 &18 May; 1 & 15 June and 31 August. AdS, PV, 6: 68r-84v; 89r-94v; 98r-107r; 173r-175r. 258 Boyle, CPE, pp. 122, 128, 130.

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attributed only to the size and shape of their corpuscles. By way of example he suggested that a heap of sand will retain a pyramid-like shape and will not flatten down, like a liquid, until it is externally shaken or moved. As to the alleged continuous motion, Huygens explained that since the particles are heavy (posses pesanteur; are affected by gravity), they could not conserve their own motion. On these grounds, Huygens deduced the existence of a super subtle matter, in rapid motion: it is all-pervasive and is the cause of the particles’ motion and corresponding state of fluidity.259 Huygens deduced the existence of the ether from the gravity assigned to the particles. The circularity is evident: ether (as the cause of pesanteur) denies the particles from conserving their motion yet (as the cause of fluidity) it provides them with the necessary continuous motion, which constitutes the liquid. In his account of fluidity, Huygens used the ether ambiguously as both cause and effect. As to coagulation or cohesion he reasoned that it was due to the loss of the motion of particles.

Unlike Descartes, however, who assigned cohesion to the lack of corpuscular motion

Huygens, perhaps influenced by Gassendi, maintained that,

material consistency is nothing but the privation of the motion of the particles, which is the cause of some kind of attachment between the them. This attachment derives, I believe, from the figure of the particles which enables them to hook onto each other and bind together; I am not of the same opinion as Mr. Descartes, who held that the lack of motion of the particles, resting upon each other, is enough to render a body very solid.260

Mariotte and Perrault expounded similar theories, referring to corpuscular texture.261

259 AdS, PV, 6; 136r-137v. 260 AdS, PV, 6: 138r. On seventeenth-century conceptions of cohesion see Millington (1945). 261 AdS, PV, 6: 126r-135r; 141r-149v.

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The recourse to the sizes and especially to the shapes and configurations of particles was a practice common to mechanical conceptions of matter. And while

Huygens, it may be argued, was not much of a chemist, Boyle is a good case in point, as corpuscular configuration and texture played a significant role in his matter theory. In his essay on fluidity Boyle repeatedly explained various aspects and changes in cohesion of substances—set in chemical processes—by recourse to corpuscular motions, sizes, shapes and configurations. Viscous egg whites, for instance, when whisked, increase in fluidity, an effect which, “seems to be produced but by pulling asunder the parts, (which perhaps before were long and somewhat twin’d) and breaking them into shorter or lesser, and consequently more voluble ones.”262 Similarly, the main difference “between solid ice and water, [is] that in the one the parts… [may have a] newly acquir’d texture.”263 Pressure,

Boyle thought, may also have similar effects, as in snow, which “in first falling, is of an open and loose texture.” By compressing it between our hands we change the order of particles, bring them into a closer order, producing small consistent (solid) icy bodies.

Boyle even went as far as to interpret the action of the universal solvent, the alkahest, along mechanical lines. In a statement reminiscent of Newton’s reference to nature’s

“variety” Boyle suggested that

if that be true which Helmont in several places affirms of his prodigious liquor, Alkahest, it is possible to turn Plants, Animals, Stones, Minerals, Metals, or whatever kind you please of consistent Body here below, into a Liquor equiponderant to the resolv’d concrete: which (if granted) seems to argue, That the most solid Body by being divided into parts small enough to be put into motion… may become fluid.264

262 Boyle, CPE, p. 127. 263 Boyle, CPE, p. 130. 264 Boyle, CPE, pp. 127-28; italics added.

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The way Duclos, in his critique, read these lines is telling. First, he remarked that the agitating action of the whisk could not change the shape of the particles or make them any rounder. Secondly, even if the compression of particles of snow makes the mass harder to the sense of touch, it does not follow that all solidity is occasioned by compression and the limitation of intra-corpuscular space. Ice is solid yet its particles are less compact; it is more extended and less heavy that liquid water. Finally, fluidity of metals dissolved in strong acids proceeds from the “discontinuation” of their particles. If not radically resolved, these particles could reunite and regain metallic solidity and properties. Fluidity caused by the alkahest, however, proceeds from a completely different cause since the liquors are unrecoverable.265 Duclos attributed motion, for instance, to a symbole between two metals (affinity), a difference in salts, or a concentration of earthy fatness by saline materials. Concerning metallic dissolutions Duclos distinguished between what can be deemed a mechanical-physical decomposition and a chymical one:

The fluidity acquired by metals in acids [eaux fortes] that dissolve them may well follow from the discontinuation of the particles of their bodies, which cannot be by such means radically resolved, and which may, by way of union restore to these bodies their primary metallic solidity. But the fluidity of bodies radically and totally resolved by means of Van Helmont’s alkahest, must proceed from some other cause than the discontinuation of the reduced particles, since these liquors are irreducible [irreversible].266

265 AdS, PV, 6: 15v-16r. 266 AdS, PV, 6: 16r: “la fluidité que les métaux acquièrent dans les eaux fortes qui les ont dissoutes peut bien procedder de la discontinuation des particules de ces corps, qui ne sont point par ce moyen radicalement résout, et lesquels, peuvent par leur réunion redonner a ces corps leur premier solidité métallique. Mais la fluidité des corps radicalement et totalement résout par l’alchaliest de Vanhelmot doibt procedder de quelque autre cause qu de la discontinuation des particules atténuées, puisque ces liqueurs sont irréductibles.”

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Duclos, as we have already seen, was not against a particulate approach, nor was he denying the influence of corpuscular motion. Yet, like in his former critique of Boyle’s explanation of the action of niter, Duclos rejected all mechanical recourse to what he considered as the imaginary sizes, shapes, configurations and textures of the particles.

Most important, unlike Boyle, whose project was a physico-chymical one—an attempt to reconcile the chymical with the physico-mechanical—Duclos, like Newton, sought to set the chymical apart from the physical and hence resist the structural reduction as well as the dogmatic denial of action at a distance.267 Duclos claimed the independence of both realms, a view that is evident in his interpretation of fluidity, coagulation and cohesion.

Significantly, the foundation of his SER was thoroughly observational and experimental.

Let us briefly examine the case of the coagulation of milk, its curdling and transformation into cheese, which can be initiated by two distinct agents: a particular application of heat and acrid, corrosive substances. Huygens assumed that milk consisted of a homogeneous mixture of two substances, represented by two types of corpuscles: the

267 A certain degree of ambiguity can be ascribed to Newton’s views on this matter. But it seems to owe largely to a discrepancy between his published material on the subject (most explicitly found in the Opticks) and his alchemical tracts. The famous 31st query (Opticks, 4th ed.,1730) may be interpreted as implying what McMullin referred to as a “one-level ontology of forces, regarded as a species of active principle.” It could be argued, in this context, that Newton suggested a kind of unification of the chymical with the physical, derived from the universality of forces, whether at the micro- or macro-material level. In this query Newton wrote concerning the changes of corporeal things, that “these particles have not only a vis inertiae, accompanied with such passive laws of motion as naturally result from that force, but also they are moved by certain active principles, such as is that of gravity, and that which causes fermentation and the cohesion of bodies.” The distinction, however, is explicit in his alchemical manuscripts; McMullin aptly pointed to the ambiguity of Newton’s notion of “active principle,” which he sometimes identified with the “laws of nature themselves, made manifest in the phenomena… [and] are thus fully known, though their ‘causes’ are not. More often, [Newton] takes the active principle to be itself the cause, the ontological constituent responsible for the motion. The term is thus for him a loose generic one.” McMullin (1978), pp. 81-82.

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milky (serum), which are small and round, and the cheesy, shaped in the form of hooks and eyes. The prolonged application of moderate heat—moderate degree of motion—increases the intra-corpuscular interactions, which result in the binding of the cheesy particles, hence the separation between the two substances. The boiling of milk, on the other hand, by imparting an extreme degree of motion, does not allow for such binding. Acrid matters consist of large corpuscles, which impart the same kind of ‘coagulative’ motion to the cheesy particles.268

Huygens claimed that we could easily imagine such a process and mechanism. For

Duclos, this was precisely where the problem lay, for there is little in his chymical SER that would validate such an explanation, no matter how imaginable, self-consistent and ostensibly intelligible. Duclos explained that there are two types of concretions (cohesive processes, causes): congelative and coagulative. The first are occasioned by heat or lack thereof and are interpreted in terms of motion and particles or sometimes by evaporation; either way, the processes are reversible: cold makes milk congeal into ice and heat reverses the process. In congelative processes there is no essential change in composition.

Coagulative processes, on the other hand, are by definition irreversible since they entail a compositional change, which Boyle might have explained in terms of corpuscular shape, size and texture. Coagulations are of two kinds: condensative and transmutational.

Condensative coagulation refers mostly to the concretion (cohesion) of particles found within a liquid, as in solutions or as in the curdling of milk, whereas transmutational

268 AdS, PV, 6: 138r-139r.

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coagulations comprise the processes by which wholesome liquids or liquid-like substances turn into solids (e.g. sap into wood; food into flesh).

Corpuscular motion was for Duclos, as for Huygens or Boyle, a physical phenomenon and hence brings about changes at the physical level, which is reversible since there is no essential change. Changes in composition—for Boyle textural and configurational changes—are chymical, essential and irreversible (transmutational). Milk cannot be recovered from cheese, just as the water or nutrients that went into a plant cannot be recovered. Duclos knew this intimately since he performed and ordered large numbers of plant distillations. Yet again, distillation is occasioned by heat, and as mentioned before, according to Duclos’s SER, is a superficial means of decomposition or analysis; it is a physical tool that works only at the level of particles and motion, which renders it analogous (direction opposed) to the process of congelative cohesion.

Returning to Newton’s distinction between the mechanical and the vegetal, between the vulgar-chymical and the vegetal-chymical, distillation is indeed associated with vulgar chymistry, in much the same way that a common distiller would have been considered (by Boyle and Duclos alike) as a simple, technical sort of chymist who knows how to obtain the various separations by way of controlling the intensity of the fire and separating the distillatory fractions. The vegetal is associated with the fermentative (e.g. cheese production), transmutational and vital; it is linked to radical dissolutions and coagulative-generative concretions, all of which belong to the realm of the chymical adept or the philosophical chymist. The latter’s SER does not yield itself to structural reductions, neither to denial of action at a distance nor of short intra-corpuscular attraction

(affinities, symbole), an aspect Newton was acutely aware of throughout his life. Just as

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Roberval and Mariotte criticized Huygens’s account of gravity for replacing one mystery with another, Duclos criticized Boyle for proclaiming the rejection of occult substantial qualities by introducing obscure and experimentally unverifiable corpuscular configurations and shapes. Boyle’s greatest pride was in his reconciliation of the physical with the chymical, thus elevating the chymical to a nobler, modern philosophical status, belonging among the ranks of the New Science. For Duclos, the adept chymist, this may have well been Boyle’s greatest drawback. The two realms are neither metaphysically nor methodologically reconcilable. Boyle’s physico-chymical compromise denied chymistry’s explanatory prowess of both the inanimate and the animate realms. This is precisely why

Newton, as Betty Joe Teeter Dobbs has argued convincingly, never relinquished alchemy, the categories of which enabled him to account for the vast “variety” of God’s creation without reducing it to matter and motion.269

269 See Dobbs (1975); Dobbs (1982).

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CONCLUSION AND INTERLUDE

Duclos’s critique of Boyle comprises a complex and multilayered historical document that can be read on several levels and within numerous contexts. It can be read as showing how one seventeenth-century savant read the work of another. It can be read as a remarkable source of information concerning the way Boyle and his natural philosophy were received on the Continent. It can be examined within the institutional context of the Academy, to explore intellectual dissidence and the way traditional views were treated and accommodated (or castigated) by a company of natural philosophers who tried to keep debate to a minimum, while becoming increasingly affected by the agendas of the budding New Science. My main interest lies in understanding what constituted distinctly chymical knowledge and the ways of its production during the Scientific

Revolution. In this context, Duclos’s reading of Boyle—qua reformer, representative of the New Science, and proponent of a novel physico-chymical discourse—provides crucial information. At the same time, by establishing Duclos’s SER, as it emerges from the critical as well as non-critical dimensions of his reading of Boyle, the complex metaphysical, epistemological and experimental interrelations pertaining to chymical practice and theory can be further substantiated and elucidated.

Boyle sought to establish a new chymical order by reconciling the chymical with the physical. As recent scholarship has demonstrated, Boyle had a far-reaching interest in alchemical (in this context: non-physical) pursuits. In a general and abstract sense, this type of argument is concerned with substantiating the continuity between alchemy and chymistry by underscoring the New Science’s debts to alchemical and other traditional

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practices. This type of scholarship is largely interested in undermining the enduring, indeed biased, portrayal of Boyle as a physically-minded chemist, a view that can be traced all the way back to Fontenelle and the early eighteenth-century. What Duclos’s depiction of Boyle affords, uniquely, is an insight into how Boyle’s endeavor—critical and constructive aspects alike—was perceived by a member of the very scientific community

Boyle sought to reform.

In line with the allegedly value-free rhetoric of the New Science, Boyle highlighted empirical standards and experimental practices. It is on these precise grounds that Duclos exposed Boyle repeatedly. Duclos faulted Boyle for his lack of experimental proficiency, but most importantly, for his lack of intimate experimental knowledge of the chymical realm of substances, procedures and practices. For Duclos, this was a knowledge of particulars, akin to and derived from an accumulation of experiences, which is why Duclos believed that a chymical practitioner must be closely acquainted with the (al)chemical corpus. Since the realm of chymical phenomena and the corresponding means of production (e.g., in the workshop) is so vast, a fine chymical experimenter must be able to distinguish between reliable and unreliable authorities. Like George Starkey, Duclos regarded certain chymical authors as authorities to whose writings and findings he deferred.270 The guiding principle here was that in face of the irreducible immensity of the realm of chemical appearances, practices, reactions, substances, and methods, a fine chymical practitioner must rely upon the experimental authority of others. In this sense,

270 See Newman & Principe (2002), pp. 174-197.

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the authoritative chymical written corpus was considered as an ever-evolving repository of legitimate chymical knowledge that could be, indeed should be, applied and relied upon.

Duclos was attentive to and receptive of Boyle’s critique of “vulgar” chymistry and its related elemental theories. Like Boyle, he agreed that neither the Tria Prima nor the peripatetic elements (or any of their combinations) comprised the true chymical elements or the ultimate constituents of mixts. Boyle, however, offered little in their stead and proceeded to introduce a new way of explaining chymical phenomena by employing the principles of motion and corpuscles, as well as their respective sizes, shapes, configurations and textures. Duclos, on the other hand, equally dismissive of the same elemental theories, sought to explain them and situate them within a broader context of chymical analysis. Duclos refused to relinquish the only entities the chymist could know—even if incompletely—substances: the material entities with which the chymist works and through which he approaches and studies natural phenomena.271 Instead,

Duclos proclaimed the irrelevance and uselessness of the quantitative definition of matter by three-dimensional spatial extension. According to Duclos’s chymistry, corporeal matter is palpable, manipulable and experimentally presentable. Unlike Boyle’s imaginary corpuscles, substances can be “handled or touched sensibly.” But particles were not lost on Duclos’s chymistry. In fact, they were employed in a specific and significant epistemological fashion. Recourse to particles and their motion, according to Duclos’s chymistry, designated the realm of physical interactions, which are superficial and hence reversible. This theme, as we shall see, persisted into the next century; transformed

271 Klein and Lefebvre (2007).

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versions of it were present in distinctions such as the one drawn by Bergman, over a century later, between “attraction of aggregation” and “attraction of composition.”

Boyle attempted to reconcile the chymical and the physical and sought to introduce physical-corpuscular intelligibility into what he considered to be the obscure world of contemporary chymistry, “shrouded in mystery.” Duclos, in contrast, aimed to keep the two realms apart and accorded each realm an independent status: physical and chymical explanations accounted for essentially different things. By knowing where the line between the two is draw one could know, for instance, the limitations of fire analysis.

Consequently, there was no need to dismiss distillation methods altogether; one needed to know their applicability and uses in chymistry. According to Duclos, blurring the line between the two domains would not make chymistry more physical and hence, predicated upon a limited and rationally deducible set of principles, more intelligible or predictable.

Quite the opposite: we saw Boyle complaining that chymical matter and manner

(experiments) were contingent, unstable and unpredictable. Duclos, once more, relied upon his lifelong accumulation of experiences and knowledge in refuting Boyle’s complaints on both theoretical as well experimental grounds. On Duclos’s account, the physical and the chymical should be kept independently separate if we are to advance our scientific knowledge. Reducing the chymical—or parts of it—to the physical would introduce confusion and, most significantly, would threaten to overshadow traditional, experimentally proven metaphysical commitments and epistemological practices. Newton was acutely aware of the importance of an accurate and intelligible distinction between the two domains. He might have avoided professing these ideas publicly but observations to

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this effect are commonly found in his writings; some of the most explicit allusions occur in the Opticks, of which the third edition was his last publication.

The myriad themes arising from Duclos’s reading of Boyle persisted into the eighteenth-century in different guises, most of which have been overlooked. Duclos’s chymical philosophy and his multifaceted rejection of Boyle’s physicalist reduction of chymistry was embedded in seventeenth-century chymical and natural philosophical discourse. The debates and shifts dealt with in Part II belong to a different intellectual and scientific climate. Applying, however, the same methodological principles in attempting to establish the early modern chemical SER, reveals, as we shall see, the ways in which some of the same themes lived on and resurfaced in the late eighteenth-century, thus affording a broader and deeper inquiry into the nature of early modern chemistry.

We have seen Duclos’s emphasis on solvents as the ultimate chymical means of resolution par excellence. All menstrua—whether corrosive, extractive or resolutive— were considered as regulative liquors, that is, as facilitating fermentative processes. G. E.

Stahl (1659-1734), establisher of phlogistic theory and chemistry, published in 1697 the

Zymotechnia Fundamentalis, the art of fermentation, in contrast to the traditional

“Pyrotechnia,” or the art of fire.272 In 1765, William Lewis (1708-1781), prominent transmitter of phlogiston theory and other Stahlian ideas (and their popularizer in Britain) wrote in his Commercium Philosophico-Technicum:

NATURAL or mechanical philosophy seems to consider bodies chiefly as being entire aggregates or masses; as being divisible into parts, each of the same general properties with the whole; as being of certain magnitudes or figures, known or investigable; gravitating, moving, resisting, etc. with

272 See Chang (2002).

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determinate forces, subjects to mechanic laws, and reducible to mathematical calculation. CHEMISTRY considers bodies as being composed of such a particular species of matter; dissoluble, liquefiable, vitrefcible [sic] combustible, fermentable, etc. impregnated with colour, smell, taste, etc. or consisting of dissimilar parts, which may be separated from one another, or transferred into other bodies. The properties of this kind are not subject to any known mechanism, and seem to be governed by laws of another order.273

This represents Lewis’s attempt at delineating the spheres of physics and chemistry. We have already encountered—in late seventeenth-century chymical discourse—some of the themes Lewis enumerated: the particularity of chemical matter, the distinctiveness of chemical properties (being “dissoluble, liquefiable, vitrefcible [sic] combustible, fermentable, etc.”), the significance of their “colour, smell, taste, etc.” Lewis’s mid eighteenth-century demarcation between the chymical and the physical is much more nuanced than Fontenelle’s. This is not only a clear indication of the shortcomings of the

“natural or mechanical philosophy,” as applied to chemistry but also a testimony to the magnitude of the difficulties entailed by attempts to submit the latter to the laws of the former. Increasingly, the problem of quantifying chemistry appeared through a transformation of a speculative geometrico-structural reduction to the view that matter is homogeneous, “being divisible into parts, each of the same general properties with the whole.” In the wake of the Newtonian Revolution, notions of gravity and mass came to the fore and replaced, in this context, the centrality of particulate perceptions of matter.

The problem of a reductive quantification of chemistry shifted from the micro- to the macro-level. Yet many of the same points of contention can be identified. Time and

273 Lewis (1763-65), p. iv. On William Lewis see Sivin (1962).

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again, chemical practitioners will show how chemical matter and material change as a subject of a SER are at variance with physical matter. Any such unification will necessarily be reductive and hence both untenable and undesirable; it will only hinder the advancement of chemical science, which is “[ir]reducible to mathematical calculation” and

“governed by laws of another order,” as the chemical practitioners treated next claimed and demonstrated.

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PART II: CHEMISTRY AND THE CHEMICAL REVOLUTION

CHAPTER 2

COLLECTING AIRS AND IDEAS: PRIESTLEY’S STYLE OF EXPERIMENTAL REASONING

INTRODUCTION: ENDURING HISTORIOGRAPHIC DIFFICULTIES

Priestley’s most recent scientific biographer, R. E. Schofield, once wrote that,

“appraisals of Joseph Priestley are filled with contradiction and ambiguity.”274 Almost half a century later, this allegation is still apt as Priestley’s scientific image has been repeatedly cast and reinterpreted by modern commentators. Commonly appraised against the background of the Chemical Revolution and the programmatic work of Lavoisier, Priestley has been interpreted as an enthusiastic experimenter and naïve empiricist who lacked the capacities to interpret his experimental results on theoretical grounds. In particular, he has been repeatedly portrayed as an accidental discoverer, a raw and unsophisticated natural philosopher who stubbornly hung onto a defunct phlogistic view and whose scientific enterprise was lacking in method, coherence and rationale.

Simon Schaffer, alluding to the violent Birmingham revolts, “under whose indulgent gaze Priestley’s house was destroyed in July 1791,” asserted that, “thanks to that cataclysm, historians have labored under a series of peculiar obligations to their subject.

The riots destroyed the vast bulk of Priestley’s manuscripts, so removing most obstacles to the creative interpretation of his published legacy.” It has been particularly difficult to

274 Schofield, R. E. (1957), p. 148. For Schofield’s two-volume biography of Priestley see Schofield (1997); Schofield (2004).

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reconstruct Priestley’s scientific practice.275 And so, with “most obstacles” eliminated, allowing for an array of “creative interpretation[s]”, the problem of Priestley’s curious historiographic predicament has proved enduring. As early as 1774, Lavoisier, in his

Essays Physical and Chemical, concluded that “Dr. Priestley’s work” was but “a train of experiments, not much interrupted by any reasoning, an assemblage of facts.”276

Priestley’s greatest conceptual rival’s depiction has become a keystone in modern evaluations of his science.

Over two centuries later, Maurice Crosland still insisted that “inconsistencies permeate[d] his writing throughout his career as a pneumatic chemist” and that “his understanding developed slowly and in a confused way.”277 Jennifer Uglow, in her study of the Birmingham Lunar Society, of which Priestley was a leading member, maintained that “his researches were hardly programmatic. Without apparent method – employing what Watt later called ‘his usual way of Groping about’ – he followed up odd leads and curious phenomena in no particular order, just wondering what they might turn up.”278 In the second volume of his biography of Priestley, Schofield asserted that Priestley’s research was “prolix and rambling, without apparent design or intent” and that “he was being empirical; he did not understand exactly what he was doing or why, and had therefore to try to describe everything he did and saw.” In line with orthodox

275 Schaffer (1984), p. 151. For a detailed account of the riots, addressing their political background, origins, and nature see Rose (1960); Robinson (1960). 276 Lavoisier (1970), p. 121. 277 Crosland (2000), p. 88. 278 Uglow (2002), p. 237.

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interpretations, he argued that “before Lavoisier, Priestley was a brilliant experimenter, afterward, a bumbler.”279

Numerous scholars, employing various approaches, have offered alternative interpretations of Priestley’s scientific enterprise and its central feature, the study of airs.

Among these, R. E. Schofield, J. G. McEvoy, Simon Schaffer and Jan Golinski, are most notable.280 The latter two have provided contextual sociologically-oriented interpretations, highlighting Priestley’s role as disseminator of scientific knowledge in the Enlightenment, while the first two have attempted to provide all-embracing conceptual structures, emphasizing the unity of his scientific thought. Taking on a social-cultural approach,

Schaffer has pointed out the importance of the contextual role of Enlightenment ideology and politics in understanding Priestley’s place in the history of science.281 Following this interpretive line, Golinski has emphasized Priestley’s role as a “dedicated communicator, motivated by the determination to establish experimental facts in the public realm… in order to advance enlightenment” in relation to various corresponding communities and audiences in which he worked and to which he addressed his writings.282 By playing up the importance of John Rowning’s and especially Roger Boscovich’s matter theories for

Priestley, Schofield’s earlier studies have situated Priestley’s chemical research within a

Newtonian framework.283 This view has been vigorously challenged by J. G. McEvoy and

279 Schofield (2004), p. 138, p. 193. 280 For a cultural contextualization of Priestley at the intersection of philosophic spectacle, politics and religion in late eighteenth-century Birmingham see Money (1988-9). 281 Schaffer (1983); Schaffer (1984); Schaffer (1987). For a more general historiographic analysis see Schaffer (1980), esp. pp. 57-66. For a recent study of Priestley’s science, theology and politics see: Eshet (2001). 282 Golinski (1992), p. 66; Goliski (1988). 283 Schofield (1961); Schofield (1964); Schofield (1967).

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J. E. McGuire in an over-arching conceptual analysis, linking Priestley’s epistemology, metaphysics, religion, science, and their roots in Enlightenment philosophy, revolving around the concept of “Rational Dissent” and based on the statement that “the key to

Priestley’s thought lies in his conception of theology.”284

McEvoy has further developed the approach based on “Rational Dissent” in interpreting Priestley’s central scientific activity: pneumatic research. In his lengthy article

Joseph Priestley: Aerial Philosopher,285 still the single most comprehensive analysis of

Priestley’s scientific methodology, McEvoy began by justly claiming that “Priestley’s scientific thought has been distorted and misinterpreted” by previous accounts “imbued with that wisdom of hindsight.”286 McEvoy’s anti-Whiggish corrective ambition was to represent “the reality of Priestley’s considerable synoptic powers.” In order to achieve this, however, he was compelled to construct a complex all-embracing conceptual scheme since his basic methodological presupposition suggested that “only by references to the epistemological, metaphysical, methodological, sociological, and theological framework…

Priestley’s work in natural philosophy can be fully appreciated.”287 Attempting to harmonize all these categories in order to make them bear upon Priestley’s pneumatic

284 McEvoy and McGuire (1975), p. 326. In his second volume of Priestley’s intellectual biography Schofield, attentive to recent scholarship, is less fascinated with Newtonianism as a key concept in interpreting Priestley’s science. He downplays the divergences between his own stand and the McGuire-McEvoy thesis, contending that the “disagreements are mostly semantic.” Schofield (2004), p. 193, fn. 43. 285 For the complete title see McEvoy (1978-9). 286 McEvoy (1978-9), I, p. 1. See pp. 1-3 for an informative survey of the first modern appraisals of Priestley’s science (including assessments by H. Holt, T. E. Thorpe, F. Jeffrey, and P. G. Hartog). A similar view is espoused by A. J. Ihde, in his classical study of the history of chemistry: “Priestley approached chemistry in the true spirit of an amateur. He was gifted with a great deal of manipulative skill and ingenuity,” but “he was completely naïve and his experiments were conducted largely without plan.” Ihde (1964), p. 46. 287 McEvoy (1978-9), I, pp. 5-6.

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research, McEvoy linked, by way of a logically consistent structure, Priestley’s general intellectual commitments with his particular chemical practice. The building blocks in this conceptual explanatory apparatus—causally connecting the abstract and general with the practical and particular—range from the “core” of “rational dissent” to “theism and determinism”, “principle of plenitude”, “propositions and judgments”, “elimination of prejudice”, to “epistemological egalitarianism” to a threefold taxonomy of “analogies”, etc.288 The result is at times enlightening with respect to the various intellectual influences on Priestley’s mind during the span of his career. Yet this interconnected series of categories and concepts falls short in elucidating Priestley’s way of reasoning in his pneumatic workshop, in manipulating airs between troughs, phials, and leather bags.

Christie and Golinski correctly indicated that in McEvoy’s analysis, “there is no interaction seen between chemistry and philosophy” and that “the actual messing about with matter did not, on this argument, reciprocally induce any change or promote any novelty in the unfaltering structure of Priestley’s overall conceptual framework.”

Moreover, they rightly called for a more elaborate account; one that would allow

“Priestley’s mind a chronology as well as his hands” and thus elucidate the interaction between his chemical practice and his philosophy. Yet as much as the authors were concerned with McEvoy’s methodological shortcomings in accounting for Priestley’s practical work, they still criticized him for “failure to place Priestley in the context of any

288 McEvoy (1978-9), I, pp. 1-39.

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chemical tradition beyond the most cursory outline of British pneumatica.”289 It is therefore still within a tradition—scientific, cultural or social—with its wide set of intellectual commitments, that the authors sought to situate Priestley’s practical work.

Recent scholarship notwithstanding, a depreciative picture of Priestley’s science has endured as all key approaches put forward—Newtonianism, Rational Dissent or the circulation of knowledge in the Enlightenment—are found wanting in dealing with his experimental work.290 Priestley was an Enlightenment polymath in the age of

Newtonianism, a political and religious nonconformist and a devout Christian. My present goal is not to deny the relevance of these external influences on his scientific activities but rather to show how various aspects of his experimentalism have been glossed over by these interpretations, so that we still need to explore the nature of his chemical research.291

As theologian, dissenter, preacher, and pneumatic chemist, Priestley developed within and interacted with larger intellectual circles: audiences, communities, and earlier pneumatic practitioners, whose books he read, whose methods he emulated, and with whom he corresponded throughout his career. Yet in a significant sense, when experimenting in his pneumatic workshop, Priestley was on his own: either systematically experimenting or assiduously reporting his experiments in writing. It is the peculiar process of interaction in which more than anything else the “hands” carried their weight

289 Christie and Golinski (1982), p. 256; Golinski has later situated Priestley in Enlightenment chemical tradition as disseminator and circulator of knowledge. His views are further referred to in the course of the essay. See Golinski (1992). 290 The three approaches can also be broadly denoted as the ‘Newtonian’, the ‘synoptic’ and the ‘social-cultural’ evaluations. 291 The historiographic debate is still open-ended. See for instance McEvoy, who refers to Christie and Golisnki as “postmodernist historians” and claims that “the postmodernist preference of specific studies of fragmented episodes in Priestley’s science is equally incapable of grasping the temporal development of his life and thought.” McEvoy (2000), pp. 75-76.

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upon the “mind,” which I wish to elucidate by closely following Priestley’s twofold pneumatic practice—experimenting and writing—regarding nitrous air.

In what follows I trace Priestley’s early production and manipulation of nitrous air in relation to his evolving understanding of its constitution and nature. Establishing an analysis of his experimental activities, I then proceed to expand it in the context of his metaphysical and epistemological perceptions. I thus depict his pneumatic activity as it was dynamically molded at the intersection of method—both experimental and literary— and epistemology.

BACKGROUND TO PRIESTLEY’S CHEMICAL PRACTICE AND WRITING(S)

Concerned mainly with the form, rather than the content, of Priestley’s chemical research Crosland claimed that “two major problems in understanding Joseph Priestley are that he wrote so much and over such a wide area”, concluding that “throughout his life

Priestley was a compulsive writer.” In the same vein, Roy Porter described him as “a polymath born with a perpetual-motion pen” who “died, almost inevitably, correcting proofs” and Uglow introduced him as “the preacher with the stuttering voice and the flowing pen.”292 Priestley indeed wrote extensively on a variety of different subjects, including “contributions in language study, English grammar, philosophy of education, rhetoric, politics, history, religion, and biblical criticism, as well as the science for which

292 Crosland (1983), p. 223, Porter (2000), p. 406, Uglow (2002), p. xiv.

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he is best known.”293 Indeed, it was “true science” which he regarded as “being the only foundation of all those arts of life… which distinguish civilized nations from those which we term barbarous.” Among scientific activities he considered pneumatic “chemistry” as of “more various and extensive use, than any other part of natural knowledge.” “The doctrine of air”, he wrote, which “was hardly mentioned in the writings of chemists, now makes a very considerable figure in the mass of chemical knowledge, and throws the greatest light on the most important processes.”294 In this spirit, employing modest, partly improvised, equipment Priestley carried out his most important pneumatic work, identifying and isolating numerous new gases.295

Despite scholarly emphasis on Priestley’s political attachments,296 late in his scientific career, he admitted that “scientifical pursuits” have priority over “political ones” since “the former are as much more favourable to the display of the human faculties than the latter, as the system of nature is superior to any political system upon earth.”297 To his contemporaries, concerned with the possibility that his extensive religious occupations impeded his experimental work, he wrote that “the attention I have given to theology…

293 Schofield (1997), p. ix. Priestley’s complete writings excluding his scientific papers were edited by J. T. Rutt in 26 volumes between 1817 and 1832: Theological and Miscellaneous Works of Joseph Priestley. 294 Priestley (1790), pp. v-vii. 295 Among these: dephlogisticated air (oxygen), fixed air (carbon dioxide), inflammable air (hydrogen), nitrous air (nitric oxide), alkaline air (ammonia), marine acid air (hydrochloric acid), and phlogisticated air (nitrogen). For a description of Priestley’s pneumatic instruments and utensils see Badash (1964). 296 See, among others, Schaffer (1984), pp. 151-152; Schaffer (1987); Eshet (2001), esp. pp. 127- 129 and 136-40; Schofield (2004), pp. 293-316. 297 Priestley (1790), p. xxvi.

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does not engross so much of my time as some persons may imagine” and made it clear that

“the greatest part of every day was spent in my laboratory.”298

Although Priestley’s first two scientific publications were concerned with the history of electricity and optics,299 he wrote more extensively on pneumatic chemistry, which was closest to his heart and which he privileged, writing in 1790, “this is not now a business of air only, as it was at the first; but appears to be of much greater magnitude and extent, so as to diffuse light upon the most general principals of natural knowledge, and especially those about which chemistry is particularly conversant.”300

His first chemical manuscript, a pamphlet entitled Directions for Impregnating

Water with Fixed Air, was published in 1772.301 It was, however, not until the end of the same year, when his “Observations on different Kinds of Air” was published in the

Philosophical Transactions, that he had first earned the attention of other European scientists and natural philosophers.302 Between 1772 and 1786 Priestley worked and wrote furiously in the domain of chemical pneumatic analysis, in which he exhibited inquisitiveness, remarkable experimental aptitude, as well as a “flowing pen.” From 1772 until his death in 1804 he did not publish any scientific manuscript that was not related to

298 Ibid., pp. xxxii-xxxiii. 299 See Priestley (1967); Priestley (1772b). 300 Priestley (1790), pp. xxiii-xxiv. 301 Directions for Impregnating Water with Fixed Air, In order to Communicate to it the peculiar Spirit and Virtue of Pyrmont Water, And other Mineral Waters of a similar Nature. 302 In June of 1773 the paper was translated into French. Furthermore, all of Priestley’s six pneumatic volumes were translated into French by Jacques Gibelin at Paris, the first three 1777- 1780 and the last three 1782-1787. See also Guerlac (1957).

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pneumatic chemistry.303 His pneumatic research was notably rich, touching on an array of themes including the manipulation of airs, their constitution and properties, volumetric assessments, as well as the study of respiration, pollution, and putrefaction reactions.

His published chemical manuscripts consist of a number of articles, and two voluminous three-volume sets: Experiments and Observations on Different Kinds of Airs

(1774- 1777) and Experiments and Observations Relating to Various Branches of Natural

Philosophy (1779-1786). These were followed by a three-volume version, bearing the same title with the addition of being the former six volumes abridged and methodized, with many additions (1790).304 Priestley’s pneumatic writings are indeed afflicted by the “two major problems” identified by Crosland: volume and variety. Throughout his involvement in pneumatic research, Priestley had followed a “method of speedy publication”305 since, he claimed, “I have been unwilling to with-hold from my reader any thing concerning which I was able to give him even imperfect information.”306 Although he was markedly diffident in his literary style, Priestley boasted towards the end of his career that, “no person who has made near so many experiments as I have, has made so few mistakes. I do not mean with respect to opinions, but in my reports of facts.”307

Scrupulous “reports of facts”, alongside detailed descriptions of experimental settings, observed phenomena, and laboratory methods are prominent in Priestley’s pneumatic volumes. Equally significant, however, are the prefaces to these volumes, in

303 His last chemical publication was The Doctrine of Phlogiston established, with Observations on the Conversion of Iron into Steel, in a Letter to Mr. Nicholson, published in 1803 one year before his death. 304 See Priestley (1775-77); Priestley (1779-1786); Priestley (1790). 305 Priestley (1790), p. xvii. 306 Priestley (1779-86), II, p. x. 307 Priestley (1800), p. 4.

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which Priestley provides an exclusive glance at his scientific philosophy. Drawing on his experience in writing in the history of science and following an “analytical and historical” structure “but as concise as possible,” he assumed a writing style that would appeal to a wide public.308 Yet Priestley was not just imparting pneumatic knowledge; as we shall see, his writing was an integral part of his SER and was thus closely linked to the dynamics of pneumatic experimentalism, method and epistemology.

EXPERIMENTAL COMMITMENTS: THE CASE OF NITROUS AIR

[B]y working in a tub of water, or a bason [sic] of quicksilver, we may perhaps discover principles of more extensive influence than even that of gravity itself.309

In 1777 Priestley wrote:

I have more than once observed that an attention to the subject of nitrous acid, and nitrous air, appeared to me to be the most promising of any inquiries relating to the business of air: as they seem to have a nearer connection with the most general and fundamental principles in the constitution of nature.310

Priestley was inspired to produce what he would later call “nitrous air” by reading Stephen

Hales’s 1733 Statical Essays and he first introduced it in an article published in the

Philosophical Transactions in 1772.311 In his first chapter on the subject312 Priestley admitted that he “was particularly struck with that experiment of his, [Hales’s]… in which

308 Priestley (1779-86), II, p. xii. 309 Priestley (1790), p. xxiv. 310 Priestley (1775-77), III, p. 103. 311 Priestley (1772a) 312 Of Nitrous Air, under the heading of Experiments and Observations made in, and before the Year 1772.

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313 common air, and air generated from the Walton pyrites by spirit of nitre [NHO3], made a turbid red mixture, and in which part of the common air was absorbed.” Priestley “never expected to have [had] the satisfaction of seeing this remarkable appearance,” since he had initially assumed it was “peculiar to that particular mineral.” In the spring of 1772, in

London, he discussed this matter with Henry Cavendish, who suggested that, “other kinds of pyrites, or the metals might answer as well, and that probably the red appearance of the mixture depended upon the spirit of nitre only.” Thus encouraged, Priestley set upon investigating the subject. Having no “pyrites” at hand, he started collecting, by means of a simple water trough, the air that was given off during the dissolution of various metals in nitric acid. “Beginning with the solution of brass, on the 4th of June 1772,” he had first obtained nitrous air, which was so named because he “procured it by means of spirit of nitre only.”314

Throughout his career Priestley exhibited a reluctance to coin new names for new kinds of air and was careful in his use of terms for denoting them. As early as 1772 he admitted being “at a loss of proper terms, by which to distinguish the different kinds of airs.”315 Nearly two decades later he still insisted on this point, explaining that “no person was ever more temperate, or more cautious, than I have been in the introduction of new terms, considering the number of new facts that I have discovered.” Instead, he stressed the significance of “using the term air as expressive of the mere form in which a substance is exhibited, without any consideration of the elements of which it consists.” In general,

313 ‘Pyrites’ denoted originally any stone that could yield sparks. Ultimately, it referred to the minerals iron sulfide (FeS2) or iron-copper sulfide (CuFe2S3). 314 Priestley (1775-77), I, pp. 108-109. 315 Priestley (1772a), p. 147.

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Priestley denoted airs either as fixed, common, mephitic, or inflammable. As an exception to this rule he employed “other appellations, drawn from the particular circumstances” under which the airs were produced. “Nitrous air” fell under this consideration alongside acid, alkaline, phlogisticated, and dephlogisticated airs.316

After having ascertained the production of this air “by the nitrous acid only” from other metals such as “iron, copper, brass, tin, silver, quicksilver, bismuth, and nickel,”

Priestley addressed “one of the most conspicuous properties of this kind of air”: “the great diminution of any quantity of common air with which it is mixed, attended with a turbid red, or deep orange colour, and a considerable heat.” He then contended that, “the diminution of a mixture of this [nitrous air] and common air is not an equal diminution of both the kinds, which is all that Dr. Hales could observe.” In a famous passage he noted:

I hardly know of any experiment that is more adapted to amaze and surprise than this is, which exhibits a quantity of air, which, as it were, devours a quantity of another kind of air half as large as itself, and yet is so far from gaining any addition to its bulk, that it is considerably diminished by it.317

Between 1772 and 1774 Priestley was engaged in extensive research on nitrous air and on this reaction in particular, which would ultimately constitute the cornerstone for the

316 Priestley (1790), pp. 8-9. 317 Priestley (1775-77), I, p. 110-111. Lavoisier, for instance, dedicated the whole first part of his 1774 Essays Physical and Chemical to a detailed summary of the views of other chemists (e.g. Boyle, Hales, Stahl, Black, Priestley, etc.). He explains Priestley’s astonishment by claiming that “the whole volume [of airs], instead of being three measures, which it should have been, in proportion to the sum of the volume, was found, on the contrary, a ninth less than the two measures, viz. less by a ninth in measure than the quantity of common air introduced into the mixture.” Lavoisier (1970), p. 152.

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science of eudiometry, further developed by the Abbé Felice Fontana and Henry

Cavendish.318

Examining in detail this observation, Priestley first sought to establish the volumetric ratios in the diminution process. After “many trials” he found out that “if one measure of nitrous air be put to two measures of common air”, the diminution will take place leaving a volume of air that “will want about one ninth of the original two measures” of common air.319 Instead of getting three measures of aerial matter, Priestley found the resulting volume to be one ninth less than the quantity of common air introduced in the first place. This came to a total diminution of one and one ninth measures of the whole volume of air. The reaction can be conveniently described in modern chemical language in the following way:320

1mNO + 2m(1/5O2 + 4/5N2)  2/5mNO2 + 8/5mN2 + 1/5mNO

In order to establish whether during the mixing of airs there was any diminution in the volume of the nitrous air alone, Priestley mixed “one ounce measure of common air” with

318 For the evolution of pneumatic instruments and the invention of the eudiometer see Levere (2000). 319 Priestley (1775-77), I, pp. 110-111. 320 This formulation is based on the assumption that common, atmospheric air, is composed of one fifth oxygen and four fifths nitrogen, the core reaction being 2NO + O2  2NO2 . For further explanation of the process see McEvoy (1978-9), II, pp. 105-106. Given that the presence of water is always implied, this depiction is lacking in that it fails to account for what has later been known as ‘multiple combining proportions’, established by Dalton (for this reaction ) in 1803. Dalton conducted experiments on the combination of nitrous gas (NO) with the oxygen in atmospheric air which demonstrated that nitrous gas reacted with oxygen in a 1:1.7 volume ratio to form nitric acid, and in a 1:3.4 ratio to form nitrous acid. It follows that the same volume of oxygen can consume two different specific volumes of nitrous gas at a general ratio of 1:2. M. C. Usselman writes: “Dalton [in 1805] recognizes his combining ratios at the two extremes of an observational continuum. Oxygen can combine with a certain quantity of nitrous gas to form the more highly oxygenated nitric acid and with a doubled quantity to form the less oxygenated nitrous acid… With intermediate quantities of nitrous gas, oxygen reacts to form mixtures of the two acids.” Usselman (2000), pp. 246-247. Usselman also points out that several reversible reactions are involved here.

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“near twenty ounce measures of nitrous air” and found that it “made an addition to it of about half an ounce measure.” He had subsequently concluded that nitrous air does not merely consume common air, since this additional “half an ounce measure” to the total volume was in fact in “a much greater proportion than the diminution of common air in the former experiment.” According to Priestley’s volumetric calculation, common air, when mixed with nitrous air, “suffers a diminution [in bulk] from one fifth to one fourth.” Since this specific diminution rate is never exceeded, as checked “in a variety of other cases”, he concluded “that part of the diminution in the former case is in the nitrous air.”321 Leaving little room for experimental doubts, Priestley exhibited great caution by repeatedly examining each and every element in his system, regardless of any hypothetical constraints.

Priestley next turned to test the water as the third entity (reactant) in his experiment. Employing a mercurial trough322, he reported having “made the whole process several times in quicksilver using one third of nitrous, and two thirds of common air, as before.” This time, “the redness continued a very long time, and the diminution was not so great as when the mixtures had been made in water, there remaining one seventh more than the original quantity of common air.” Since Priestley performed the same experiment

“several times,” this result by itself could qualify as decisive, at least in the sense that water does contribute to the diminution of the aerial volume more than mercury does.

Priestley, however, exhibiting extreme prudence in establishing conclusions on

321 Priestley (1775-77), I, pp. 111-112. 322 Most gases that are soluble in water are not soluble in mercury and thus by substituting the water in the trough with mercury the results would be different.

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experimental grounds, expanded the experimental setting by performing two versions of the same test. In the first case he admitted water into a vessel with the “mixture [of airs], which had stood about six hours on the quicksilver.” In the second he repeated the same procedure, only this time with a mixture that “had stood but a very short time in quicksilver.” He then concluded that in the second experiment the “farther diminution” of the mixture, following the initial reaction, was “much more considerable.” Priestley first performed the process over water and then substituted water with mercury. Upon observing a difference between the two instances, he tested the airs during reaction and in relation to time. Only then was he prepared to conclude that, “the diminution is in part owing to the absorption by water.”323

Priestley meticulously designed and diversified the given experimental setting and has carefully considered all constituents and sensible reactants. Yet he did not attempt, at this stage of the narrative, to account for the nature of the water-soluble substance. He was, however, concerned with phenomenal and qualitative factors observed. Referring to the color of the fumes expelled, their smell, observed effervescence and sensible heat given off,324 it can be argued that his ultimate experimental interests were qualitative, placing him within the sensualist empirical tradition.325 Yet such an interpretation could not account for his obsession with establishing accurate volumetric measures; he was at least

323 Priestley (1775-77), I, pp. 112-113. 324 Priestley (1775-77), I, pp. 110-113. 325 For an indication of Priestley’s sensationalist basis for ideas see McEvoy (1978-9), I, pp. 18-20. For a genealogy of the sensualist tradition in chemistry and its demise in the eighteenth-century see Roberts (1995).

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equally engrossed in a precise quantitative establishment of aerial volume ratios, a practice entailing accurate measurements and fine instrumental manipulation.

Priestley in fact openly denied the possibility of establishing an exhaustive experimental account, overcoming all the scientific and epistemological challenges encountered in the experimental realm: “I find it absolutely impossible to produce a work on this subject that shall be anything like complete. My first publication I acknowledged to be very imperfect, and the present, I am ready to acknowledge, is more so.” This might seem “paradoxical” but “this will ever be the case in the progress of natural science… In completing one discovery, we never fail to get an imperfect knowledge of others, of which we could have no idea before; so that we cannot solve one doubt without creating several new ones.”326 The pursuit of new discoveries, then, as a means for advancing in science is epistemologically superior to pursuing a single line of inquiry. In line with the “the progress of natural science” Priestley pressed on with his experimental reportage.

His next observation was related to a “most agreeable” discovery and “an useful one” too:

It is exceedingly remarkable that this effervescence and diminution, occasioned by the mixture of nitrous air, is peculiar to common air, or air fit for respiration; and, as far as I can judge from a great number of observations, is at least very nearly, if not exactly, in proportion to its fitness for this purpose; so that by this means the goodness of air may be distinguished much more accurately than it can be done by putting mice, or any other animals, to breathe in it.327

326 Priestley (1775-77), I, p. vii. 327 I Priestley (1775-77), I, pp. 114-115.

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Deduced from “a great number of observations”, encountering this “remarkable” phenomenon was highly pleasing for Priestley, who immediately grasped the pragmatic benefits implied by this feature of nitrous air. He was particularly excited about prospects of finding a technique to assess the “goodness” of the air by measuring its diminution when mixed with nitrous air.328 Making sure that “on whatever account air is unfit for respiration, this same test is equally applicable”, he tested other “fit” airs and found out that “there is not the least effervescence between nitrous and fixed air, or inflammable air, or any species of diminished air.” This “test” seemed all the more promising since the diminution occurred on a “large scale”, ranging “from nothing at all to more than one third of the whole of any quantity of air.” Testing air injured by “candles burning in it,”

Priestley was able to ascertain not only “the degree of injury” but also its “kind”, that is,

“whether it was at all injured with respect to respiration”, which he could not have established accurately beforehand by the sole use of mice.329

During 1773-74,330 Priestley produced nitrous air by evaporating “to dryness a quantity of the solution of copper in diluted spirit of nitre” and then heating the “green precipitate” over mercury. He then explained “that part of the same principle which had escaped during the solution, in the form of air, had likewise been retained in it, and had not left it in the evaporation of the water.” This time he produced it in order to “discover

328 On Priestley’s perception of science as a beneficial program see McEvoy (1978-9), part I. 329 Priestley (1775-77), I, p. 115. The use of mice was limiting since deductions from their observable state, upon breathing the aerial sample, were only roughly indicative as to its composition. In the same chapter Priestley also reports the following: (a) that nitrous air is heavily diminished by a mixture of iron filings and brimstone, pp. 118-119. (b) that by impregnating water with nitrous air, the water would imbibe one tenth of its bulk of the air, pp. 120-122. (c) that nitrous air has an antiseptic power and the capacity of slowing processes of putrefaction, pp. 123-125. 330 The corresponding chapter is Experiments and Observations made in the Year 1773, and the Beginning of 1774.

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where the power of nitrous air to diminish common air lay.” Unlike his 1772 reports, in which he refrained from providing theoretical explanations regarding the chemical mechanisms involved, here, Priestley set about to explain the “nature and constitution” of this air. The 1773-74 report on nitrous air opens with a promise for a “more satisfactory account” of the air and of the diminution phenomenon previously observed. He added that, “since the publication of my former papers, I have given more attention to the subject of nitrous air than to any other species of air.”331

Following Priestley’s original order of presentation is, at first glance, confusing.

Having described the way by which he produced nitrous air, he proceeded to elaborate in detail on an incident in which he “fired some paper, which had been dipped in a solution of copper in diluted spirit of nitre, in nitrous air.” This experiment, he admitted, was performed “for a different purpose”, which is not revealed. When the “paper” was ignited in nitrous air, “there was a considerable addition to the quantity” of aerial matter.

Typically, he performed and repeated this experiment over both water and mercurial troughs. When ignited “in quicksilver,” air was produced from the paper in “great quantity.” Without further explanation, Priestley reported that, “this air, at the first, seemed to have some singular properties.” Shortly after, however, he concluded that it

“was nothing more than a mixture of nitrous air, from the precipitate of the solution, and of inflammable air, from the paper.” He subsequently mixed the same air (burned “copper” air) with common air in order to observe the expected process of aerial diminution but came across an occurence which, he observed, “exceedingly delighted and puzzled me: but

331 Priestley (1775-77), I, pp. 203-204.

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which was afterwards the means of letting me see much farther into the constitution of nitrous air than I had been able to see before.”332

Priestley had mixed the air with common air in a trough over putrid water. As expected, the action resulted in the diminution of the aerial volume in the trough.

However, “when the diminution of the air was nearly completed, the vessel in which the mixture was made began to be filled with the most beautiful white fumes, exactly resembling the… falling of very fine snow.” He then repeated the process, as “nearly as possible in the same manner,” but could not reproduce the phenomenon. This “greatly disappointed” him as he failed to exhibit the “white fumes”333 before friends.

Systematically attempting to replicate the experiment, Priestley claimed to have taken “a great deal of pains to procure a quantity of this air from the [copper] paper… by a small burning lens.” He ultimately concluded that this special air could not have been responsible in any way for the appearance of the clouds. By meticulously making, remaking, and repeating the experiment, he found out that he could actually obtain the

“same appearance from a mixture of nitrous and common air in the same trough of water.”

What Priestley had observed, during his replication efforts, was a certain irregularity in the appearance of these white clouds. This caught his attention as he was eager to reproduce the phenomenon and because he expected it to occur every time “he went over the same process, as nearly as possible in the same manner.”334

332 Priestley (1775-77), I, pp. 204-205. 333 Priestley refers to these “fumes” also as “clouds”, using the terms “white clouds” and “white fumes” interchangeably. 334 Priestley (1775-77), I, pp. 205-206.

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Clearly, in this case, Priestley’s investigational awareness—and his deliberate and systematic refusal to draw experimental conclusions unless convinced that the experiment was fully and stably replicable—facilitated the understanding that the burned (copper) air did not in fact have any key role in this reaction. This discovery in itself might seem trivial. Priestley, however, could have just as easily attributed the appearance of the “white fumes” to the action of the single obvious and heretofore unrelated factor in this specific experimental setting: the air obtained from the burning of copper paper in the presence of nitrous air. Had Priestley not elaborated in writing about the course of his reasoning, and by doing so, revealed some of its weaknesses, we could not have been able to fully appreciate the methodological circumspection underlying his SER. We can consequently assume that Priestley wanted to convey this exact notion to the reader. His writing makes the experiment appear as an investigational path followed arbitrarily. Yet it is here, in such cases, that his rhetorical considerations might attain a broader meaning, if permitted.

Priestley’s own words shed light on the way he experimented and reasoned. He reveals himself as a careful and systematic experimenter and, contrary to the common view, a thoughtful writer.

Let us return to Priestley’s experiment and the problem of the white fumes. He reported that, having “opened the mouth of a phial which was half filled with a volatile alkaline liquor, in a jar of nitrous air… I had an appearance which perfectly explained the preceding” appearance of the white clouds. Priestley had originally observed the “white fumes” upon mixing nitrous air with common air in a trough over some putrid water. The putrid matter had typically released volatile alkali vapors (ammonia), a substance that

Priestley had tested for yet another different purpose: to see “whether any crystals would

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be formed by the union of volatile alkali, and nitrous air, similar to those formed by it and fixed air.” Now, by inserting a “phial” containing “volatile alkaline liquor” into a jar with nitrous air he observed the appearance of the same “white fumes.” Upon removing the

“phial” and exposing it to common air there would be observable turbidity and then the

“phial” would become transparent again.335 Priestley repeated this several times, each time achieving the same observable result. Furthermore, the “white fumes” were produced

“with any substance that contained volatile alkali, fluid or solid.” This observation, alongside the alternation of the fumes with transparency in the vessel, led him to conclude that both this phenomenon and the original appearance of the “white clouds” were similarly induced by “the mixture of the nitrous and common air, and therefore… the white clouds must be nitrous ammoniac.” Finally, Priestley offered a conceptual mechanism to explain the reaction of aerial diminution. The “acid of the nitrous air”, he claimed, is “set loose” from it by the “common air” which then decomposes the nitrous air.

Simultaneously, “the phlogiston, which must be another constituent part of nitrous air, entering the common air, is the cause of the diminution it suffers in this process.” This, he concluded, “is the true theory of the diminution of common air by nitrous air.”336

Regarding the phenomenon of “white fumes”, none are observed “when the salt

[solid volatile alkali]337 is put into the nitrous air itself.” This, he explained, owes to the fact that “the acid of the nitrous air has a nearer affinity with its phlogiston than with the volatile alkali.” On the other hand, when common air is present in the mixture, “the

335 The transparency owes to the dissolution of the fumes in the water. 336 Priestley (1775-77), I, p. 206-208. 337 Usually ammonium carbonate NH4CO3 or in ammonium hydroxide solution ((NH4)2CO3).

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phlogiston having a nearer affinity with something in the common air,” the acid of the nitrous air will be “set loose” and “unite with the alkaline vapour” resulting in the “white cloud.”338 Priestley’s explanation was based on a modest theoretical framework: phlogiston’s power to diminish aerial volume, known to him from other experiments, and the acidic nature of nitrous air: it “is of an acid nature, as well as fixed air.”339 Hence the

“white clouds” originated in the decomposition of the nitrous air by common air which is then diminished by phlogiston, the other constituent of nitrous air.

THE SCIENCE OF MAKING AND THE MAKING OF SCIENCE: PRIESTLEY’S SER

[I]n this science mere observation and reflection will not carry a man far. He will frequently have occasion to put the substances which he examines into various new situations, and observe the result of the circumstances, which, without expence, as well as labour, he can have no opportunity of knowing.340

[S]o great is the difference between writing from the head only, and writing, as it may be called, from the hands.341

Numerous commentators, as we have seen, have condemned Priestley for making do with superficial chemical explanations, confined mainly to a phlogistic framework, thus portraying him as a naïve empiricist and unsophisticated theoretician. However, such

338 Priestley (1775-77), I, p. 211. 339 Priestley (1775-77), I, p. 215. When nitrous air is exposed to iron it transforms into what Priestley named ‘inflammable nitrous air’ or ‘dephlogisticated nitrous air’, of which he writes: “air in which a candle burns quite naturally and freely, and which is yet in the highest degree noxious to animals”. The reaction, in modern chemical language, is: 2NO + Fe  N2O + FeO (N2O is both inflammable and soluble in water). See also Priestley (1779-86), II, pp. 192-202. 340 Priestley (1790), pp. vii-viii. 341 Priestley (1779-86), I, p. vi.

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interpretations overlook various aspects of his SER: his experimental conduct in light of his perceptions of science, his literary strategies and the way these factors interacted to generate pneumatic knowledge. In establishing the nature of Priestley’s SER, by focusing on an analysis of his chemical practice and reportage, I follow his own emphasis on praxis and experience. The use of SER provides access to the point of interaction between

Priestley’s hands and his head and, ultimately, between his chemistry and philosophy.

From this methodological standpoint, the core of Priestley’s scientific work is disclosed and brought to light, a nucleus left unexplored by other interpretations.

Recalling the “copper paper” incident, Priestley reported having discovered this unique air by accident. He then described the way by which he obtained it while performing what he recognized as a non-related procedure. A little further on, he reported that none of his experimental findings could have possibly depended “upon any thing peculiar to the precipitate of the copper contained in the paper from which the air was procured,” as he had previously believed.342 Priestley, prima facie, provided the reader with details that could have been safely omitted. He shared in considerable detail the chronicles of this air from its production by the burning of the copper paper in nitrous air.

He then concluded that this air had no role in the experiment since he could obtain the very same experimental results by using merely “a mixture of nitrous and common air.”

342 Priestley (1775-77), I, pp. 205-206.

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This might seem as an odd way of writing science in an era in which quantification, precision, and methodological decisiveness would shortly win the day in chemistry.343

Priestley’s chemical volumes contain, as their title suggests, “experiments” and

“observations.” These, however, are not Priestley’s laboratory notebooks or private diaries, which were destroyed in the 1791 Birmingham riots.344 These are published artifacts, consisting of an edited series of experimental pneumatic reports and reflections upon scientific method and epistemology. His narrative is undoubtedly selected, edited and abbreviated. Priestley declared having “written much more concisely than is usual with those who publish accounts of their experiments” and that,

In this treatise the reader will often find the result of long processes expressed in a few lines, and of many such in a single paragraph; each of which, if I had, with the usual parade, described it at large (explaining first the preparation, then reciting the experiment itself, with the result of it, and lastly making suitable reflexions) would have made as many sections and chapters, and have swelled my book to a pompous and respectable size.345

Referring to his “treatise”, Priestley did not consider his writings to be a mere collection of reports but rather as a consistent narrative based on order, arrangement and eloquence.

Nevertheless, even if we were to assume that Priestley indeed chose deliberately, and for a good reason, to incorporate the description of the copper paper incident, we would still be hard pressed to speculate on the nature of this rationale.

343 On the common narrative regarding the evolution of chemical ideas in the eighteenth century see Knight (1992). On the quantification of chemistry and the Chemical Revolution see Guerlac (1961). 344 See fn. 275 345 Priestley (1775-77), I, pp. x-xi.

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This peculiar way of presentation is neither extraordinary nor rare in Priestley’s narrative. Shortly before reporting that “agreeable discovery” by means of which “the goodness of air may be distinguished,” Priestley was concerned with determining “whether the fixed part of common air was deposited in the diminution of it by nitrous air.” He typically described in detail two methods of testing for this deposition of fixed air in the vessel: by inserting a small container of lime-water and by performing the whole experiment in lime-water. He then concluded that only the latter method is decisive since by employing the first method, “no precipitation” of the “lime-water” is sensible whereas by applying the second method the precipitation is “sufficiently” sensible. Here, too, one can wonder why Priestley, having established an unassailable experimental result, found it necessary to describe in detail both experimental settings. At this point Priestley advanced a distinct explanation by stating that, “I have made no alteration, however, in the preceding paragraph [referring to the first method], because it may not be unuseful, as a caution to future experimenters.”346 By providing the reader with descriptions of both successful as well as less-successful methods, Priestley sought a more expressive way of illustrating the experimental setting, accentuating experiential dimensions as discerned by the chemical practitioner.

This rhetorical approach, to be sure, has contributed to his portrayal as an amateur and naïve experimentalist.347 Yet Priestley himself, in the preface to the first volume openly admitted that “in this work, as well as in all my other philosophical writings,”

346 Priestley (1775-77), I, p. 114. 347 See for instance Crosland who claims that, “Priestley’s reputation is liable to suffer from his transparent honesty and his willingness to commit his early speculations to print alongside

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I have made it a rule not to conceal the real views with which I have made experiments; because though, by following a contrary maxim, I might have acquired a character of greater sagacity, I think that two very good ends are answered by the method that I have adopted. For it both tends to make a narrative of the course of experiments more interesting, and likewise encourages other adventurers in experimental philosophy; shewing them that, by pursuing even false lights, real and important truths may be discovered, and that in seeking one thing we often find another.348

This passage presents in a nutshell numerous important aspects of Priestley’s SER. The

“real views” Priestley referred to are in effect experimental perceptions, which are dynamically formed and reformed, fashioned and refashioned, according to results and data established in the experimental realm. These views, or methodological intimations, can either be experimentally refuted and consequently abandoned (or put to a different use) or reformulated in face of experimental reality. Priestley, moreover, pointed out the potential influence that these views may have on other experimenters, encouraging “other adventurers in experimental philosophy” thus laying the foundations for future discoveries.

In this context, as mentioned, scholars have underlined Priestley’s role as communicator and disseminator of knowledge. This line of interpretation, although successful in fashioning Priestley’s place within the public scientific arena, obscures epistemological and metaphysical aspects of his SER.

Undeniably, Priestley’s SER owes something to his avid interest in engaging in experimental philosophy and practice and, as Golinski claimed, “to insert his own discoveries into the expanding public culture of science.” His extensive description of

descriptions of his experiments. Most other chemists were more discrete, so only by having access to their private laboratory notebooks does the historian have any chance of reconstructing their early ideas.” Crosland (2000), p. 97. 348 Priestley (1775-77), I, pp. ix-x.

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experiments, moreover, was in part meant to “persuade the general reader of their truth” and “exhaustive circumstantial details were given to ease the replication of experiments.”349 Priestley’s detailed accounts, however, were more than intended to promote experimental authority and replication. He held that,

if we wish to lay a good foundation for a philosophical taste, and philosophical pursuits, persons should be accustomed to the sight of experiments, and processes, in early life. They should, more specifically, be early initiated in the theory and practice of investigation, by which many of the old discoveries may be made to be really their own; on which account they will be much more valued by them.350

Notably, Priestley referred to “the sight of experiments” as a means of understanding experimental philosophy and the “theory and practice of investigation.” This is, after all, precisely what he tried to convey to the reader by way of his experimental reportage: a glimpse into the laboratory by way of (metaphorically) opening a textual window into the pneumatic workshop. As part of the effort to have readers “early initiated in the theory and practice of investigation” Priestley’s pneumatic reports were arranged according “to the order of time, and of discovery.” This, he claimed, should “enable the reader to enter into my views, and trace the actual progress of my thoughts in the several investigations.”351

Far from writing compulsively, as Crosland suggested, or having to “describe everything he did and saw” for want of understanding, as Schofield claimed, his writing was the outcome of a well-calculated literary strategy. Golinski rightly observed Priestley’s

349 Golinski (1992), p. 82. 350 Priestley (1779-86), I, pp. ix-x. 351 Priestley (1790), p. xvi.

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intentions to facilitate “replication” in attempt to contribute to “the expanding public culture of science.” Priestley’s SER, however, implies a wider significance.

Priestley’s narrative is in fact a stage on which the “sight of experiments” is exposed in an attempt to show the way “experiments, and processes” look when they take place. He was concerned with conveying to the reader, through his text, the practical dimension of experimental philosophy, passing on the dynamic “sight” of occurrences in the experimental setting. 352 Comparing narratives of “a metaphysical nature” with his pneumatic writings, he claimed that

single sections in this work have cost me more than whole volumes of the other; so great is the difference between writing from the head only, and writing, as it may be called, from the hands. To the former little or nothing is requisite but calm reflection; whereas to the latter much labour, and patience, and consequently much time,” are needed.353

Indeed, it was this patient “labour” that led him to observe that the mixture of nitrous and common airs was “attended with a turbid red, or deep orange colour, and a considerable heat.” Contrarily, “inflammable air with a mixture of nitrous air burns with a green flame”354 and it is “remarkable that… there is not the least effervescence between nitrous and fixed air, or any species of diminished air.” Writing “from the hands”, Priestley described the glass container which gets “filled with the most beautiful white fumes, exactly resembling the precipitation of some white substance in a transparent menstruum,

352 Discussing Boyle’s literary strategies, Shapin and Schaffer make a similar point, referring to what they call “virtual witnessing”: a technology that “involves the production in a reader’s mind of such an image of an experimental scene as obviates the necessity for either direct witness or replication.” Shapin and Schaffer (1985), p. 60; see also. pp. 60-65 and pp. 225-226. 353 Priestley (1779-86), I, p. vi. 354 Priestley (1775-77), I, p. 117.

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or the falling of very white snow; except that it was much thicker below than above, as indeed is the case in all chemical precipitations.”355

There is, then, more to Priestley’s text than just making the “narrative of the course of experiments more interesting” and encouraging “other adventurers in experimental philosophy.” Priestley’s SER evokes an epistemological dimension, incorporating the chemical experience itself into the process by which pneumatic knowledge is generated.

Chemical knowledge is not merely derived from experience (as part of a simplistic empiricist perspective) but is actually identified with the physical investigational experience: the knowledge acquired only by the producer of phenomena. Priestley further explained that by following an experimental path, that is, by physically engaging in experimental practice, practitioners can make “old discoveries… to be really their own.” It is subsequently only by means of practical engagement that one can achieve true and intimate knowledge of the natural world.

As early as 1767 he wrote that, “philosophy exhibits the powers of nature, discovered and directed by human art.”356 In this sense Priestley can be seen as a late, anachronistic, instance of the Maker’s Knowledge tradition, with its origins in old scientific practices, which was first systematically incorporated into the philosophy of experiment by Bacon, who commended “man’s dominion over nature through scientific art.”357 Priestley indeed revealed his methods and “the real views with which” he had

355 Priestley (1775-77), I, p. 205. 356 Priestley (1966), p. iv. 357 Crombie (1994), II, p. 1201. Crombie describes the notion ‘Knowing is Making’ (as part of the Hypothetical Modelling, one of six his Styles of Scientific Thinking) and the relations between experimental philosophy and art, as exemplified by late seventeenth century natural philosophers such as Boyle and Hooke: “in a subject-matter composed of engineering solutions, the answer was

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“made experiments” in order to have the reader properly “initiated in the theory and practice of investigation.” Furthermore, he provided exhaustive and qualitative descriptions of the experimental processes, as well as illustrations of his instruments as means to portray in writing “the sight of experiments, and processes.” Nothing surpasses, however, the knowledge of the maker, the experimenter, the practitioner of “experimental philosophy,” who is famously contextualized by Priestley in “the diversion of hunting,” in which “those who have beat the ground the most… are consequently the best acquainted with it.”358 Priestley drew attention to the epistemological supremacy gained by the maker, the producer of experimental phenomena who engages in experimentation by investing his own time “expence, as well as labour.”

Yet Priestley went even further with this view, encouraging experimental conduct in the pursuit of “even false lights.” As seen in his reports on nitrous air, Priestley’s meticulous and systematic experimental practice was established on the maxim “that in seeking one thing we often find another.” His pneumatic reports are indeed intended in part to “encourage new adventurers, by shewing them that, notwithstanding the many errors to which even the most sagacious, and the most cautious, are incident, their labours may be crowned with considerable success.”359 This perspective is further embedded in a broader methodological conviction, advancing the pursuit of “false lights” to the extent that the experimental philosopher “must hazard his own reputation so far as to risk even

to look for the particular engineering involved. This might be chemical or organic as much as mechanical.” (p. 1193). See also Perez-Ramos (1988), esp. pp. 48-65. 358 Priestley (1775-77), I, p. xi. 359 Priestley (1790), p. xvi.

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mistakes in things of less moment.”360 This in turn is linked to Priestley’s scientific distinction between facts and theories, discoveries and hypotheses, and their relation to practical experimentalism.361 “We are, at all ages,” he claimed,

but too much in haste to understand, as we think, the appearances that present themselves to us. If we could content ourselves with the bare knowledge of new facts and suspend our judgment with respect to their causes… [readers] are to consider new facts only as discoveries, and mere deductions from those facts, as of no kind of authority; but to draw all conclusions, and form all hypotheses, for themselves.362

In line with his practical prudence, the production of experimental “appearances” and artifacts, or “new facts”, is accorded epistemological priority. As revealed by his experimental conduct, “caution” and a reluctance to hastily “understand” or hypothesize, is of leading significance. For “all that is properly meant by a theory,” he held, “is a number of general propositions, comprehending all the particular ones, deduced from single experiments.”363 It was within this epistemological framework that Priestley “deduced from many experiments” the explanation of the reaction between nitrous and common air, involving phlogiston’s power to diminish airs, and the acidic nature of nitrous air. The same applies to his explanation of the “white fumes” phenomenon, dependent on the modest assumption that phlogiston has “a nearer affinity with something in the common air”, displacing the acid of the nitrous which is subsequently given off, to “unite with the alkaline vapour” in forming the “white clouds.”

360 Priestley (1775-77), I, p. ix. 361 For a discussion on Priestley’s distinction between fact, hypothesis and theory see McEvoy (1978-9), pp. 32-35. 362 Priestley (1779-86), I, pp. x-xi. 363 Priestley (1779-86), II, p. vii.

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CONCLUSION

Priestley urged fellow experimenters not to theorize hurriedly and “to draw all conclusions, and form all hypotheses, for themselves.” According to his SER, he advised experimenters to give priority to “bare knowledge of new facts and suspend [their] judgment with respect to their causes.” He did not, however, condemn hypothesizing in general, but warned—in line with his lifelong religious and political convictions—against dogmatism, both experimental and epistemological. Priestley compared experimenting to

“hunting”, experimenters to “adventurers” and made reference to “the appearances that present themselves to us” as part of his insistence on the experiential and practical factors in acquiring knowledge. As long as the natural unfolding of the investigational experience is not inhibited, Priestley’s SER allows for the solidification of experimental instances

(facts) under the “authority” of “hypotheses.” If constructed cautiously and not regarded as conclusive or definite, hypotheses do have their place, as he pointed out: “consider the facts, and endeavor to frame some hypothesis by which to account for them; and do not decide in half an hour, on an inquiry which well deserves the study of a great part of your lives.”364 On a metaphysical level, alluding again to the practical dimension and method of experimental inquiries, he asserted that,

everything that we do is putting things in situations, in which the laws of nature determine the result; the more perfect knowledge we have of those laws, the better we must be able to foretell those results, and therefore to chuse what we wish to produce.365

364 Priestley (1779-86), III, p. xviii. 365 Priestley (1779-86), III, p. vi.

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This, of course, draws on Priestley’s assumption regarding “the uniformity of the laws of nature” but also on his epistemological skepticism and his vision concerning the inexhaustibility of nature.366

Identifying natural knowledge with light, for Priestley, “the greater the circle of light, the greater the boundary of darkness by which it is confined.” Moreover, “no philosophical investigation can be said to be completed, which leaves anything unknown that we are prompted by it to wish we could know relating to it.” Yet despite this epistemological skepticism, Priestley admitted that “such is the necessary connection of all things in the system of nature.” The answer to this skepticism lies, again, in the act of making, of producing effects; in continually “putting things in situations,” making

“mistakes in things of less moment,” and constantly revealing our methods and experimental intimations, for “every discovery brings to our view many things of which we had no intimation before.”367 Nature, Priestley happily contended, “is a rich mine, in which we shall never dig in vain.”368

Priestley’s SER, derived from a reconstruction of his experimental activities, provides no evidence to support the idea that he was an unsophisticated, amateurish, natural philosopher and therefore confined himself to the empirical realm, where he could utilize his practical skills. Quite the contrary: Priestley’s SER embodies a well-invested and rounded perspective in favor of practical conduct in both the pneumatic workshop as well as at the writing desk. For Priestley, pneumatic knowledge was generated by the

366 Priestley (1779-86), III, p. xiv. This point can be seen as an instance of the so-called “prardoxical” nature of Priestley’s thought. 367 Priestley (1790), pp. xviii-xix. 368 Priestley (1779-86), III, p. vii.

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interactions between continuously “putting things in situations”, watching carefully for

“the appearances that present themselves to us” and “writing, as it may be called, from the hands.”

EXCURSUS: REREADING PRIESTLEY OUT OF (TRADITIONAL) CONTEXT

With most scholarly attention given to the Chemical Revolution, canonical history of eighteenth-century chemistry tells an uneven and partial tale. With few exceptions, the

Chemical Revolution has been over-commemorated as synonymous with the last phases of a theoretically-oriented phlogistic dispute.369 No single chemist’s image seems to have suffered graver distortions, due to this imbalance, than Priestley’s. He has been traditionally depicted as Lavoisier’s less competent rival, a firm opponent of the French sweeping reformation in chemistry and a lifelong defender of an outdated scientific doctrine. His pneumatic discoveries and experimental aptitude, alongside his polemical character and “flowing pen,” on the other hand, have made him difficult to dismiss from the chronicles of science. Just as his life-long religious dissent was incompatible with religious orthodoxy, so his scientific enterprise refuses to fit into rigid historiographic categories.

Repeatedly evaluating his experimental work against the background of the programmatic work of Lavoisier and the increasing emphasis on precision and quantification in science, how are we to understand Priestley’s perception encouraging

369 For more sensitive and rounded accounts of eighteenth-century chemistry see, for example, Holmes (1989); Kim (2003).

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risking “mistakes in things of less moment” and pursuing “even false lights”? How should we value his plea “not to conceal the real views”; knowing it was made in an increasingly authoritarian age? And what should we make of his idea—with its unhindered alchemical resonance—that experimentation can enable practitioners to make “old discoveries… to be really their own”?

As Priestley’s SER indicates, he had situated at the center of his scientific pursuits—literary and experimental, private and public, epistemological and moral—the practitioner, the indispensability of his “labour,” and the expansion of investigational experience. Although what has been known as the Maker’s Knowledge tradition has earlier origins in alchemy, metallurgy, medicine, natural magic, etc., Bacon was among first to incorporate it systematically in a methodical philosophy of experiment. Situating

Priestley in a Baconian (and further Boylean) context lies beyond the scope of this chapter but merits further attention. For now, I shall draw only a few key parallels, suggesting alternative grounds for interpreting Priestley’s SER in a wider historical context.

Referring to “alchemy,” Bacon offered a “fable” concerning a “husbandman that,”

when he died, told his sons that he had left unto them gold buried underground in his vineyard; and they digged over all the ground, and gold they found none; but by reason of their stirring and digging the mould about the roots of their vines, they had a great vintage the year following: so assuredly the search and stir to make gold hath brought to light a great number of good and fruitful inventions and experiments, as well for the disclosing of nature as for the use of man’s life.370

Nearly two centuries later, Priestley’s SER drew extensively on the moral of this fable:

Bacon’s “search and stir” had become Priestley’s experimental staple. Priestley argued

370 Bacon (1973), p. 30, italics added.

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that, “in completing one discovery, we never fail to get an imperfect knowledge of others” while Bacon reminded us that, “when you carry the light into one corner, you darken the rest.”371 Central to Priestley’s SER are, as the title of his pneumatic volumes suggests, experimentation and observation, as well as the reluctance to hypothesize and solidify scientific knowledge (from coining new names to framing broad theories). In a similar vein, Bacon maintained that “knowledge, while it is in aphorisms and observations, it is in growth: but when it once is comprehended in exact methods… it increaseth no more in bulk and substance.”372 While Priestley claimed that “everything that we do is putting things in situations, in which the laws of nature determine the result,” Bacon held that “all man can do to achieve results is to bring natural bodies together and take them apart;

Nature does the rest internally.” Finally, just as Priestley in his SER pointed to the shortcomings of all-encompassing theoretical structures, so Bacon asserted:

Even the results which have been discovered already are due more to chance and experience than to sciences; for the sciences we now have are no more than elegant arrangements of things previously discovered, not methods of discovery or pointers to new results.373

With this methodical emphasis on experimental pursuit, searching and the expansion of investigational experience, it should come as little surprise that Priestley was not impressed by Lavoisier’s steadfast commitment to instrumental precision, quantification and revisionist nomenclature. From Priestley’s epistemological (as well as political and religious) anti-authoritarian perspective, Lavoisier did little to improve chemical research.

371 Bacon (1973), p. 27. 372 Bacon (1973), p. 32. 373 Bacon (2000), pp. 33-34; aphorisms IV and VIII, respectively.

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At best, Lavoisier introduced “elegant arrangements of things previously discovered.” At worse, by reducing the “practice of investigation” to a mere adherence “to the rule of the balance,” Lavoisier’s system denied experimental chemistry the essential possibility that

“every discovery brings to our view many things of which we had no intimation before.”

Lavoisier’s “algebraic vision of chemistry” and his “grammatical understanding of nature”374 have supplanted Priestley’s buoyant intimation that nature “is a rich mine, in which we shall never dig in vain.” As late as 1800, referring to Lavoisier’s oxidation theory, Priestley still complained that, “the experiments adduced in support of it being not only ambiguous, or explicable on either hypothesis, but exceedingly few.”375 Indeed, what for the analytically-minded Lavoisier was but “a train of experiments, not much interrupted by any reasoning” was for Priestley the lodestar and foundation of true scientific knowledge.

374 Kim (2003), p. 380. 375 Priestley (1800), pp. 76-77, italics added.

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CHAPTER 3

RICHARD KIRWAN’S “INGENIOUS MODIFICATIONS… INTO THE THEORY OF PHLOGISTON”

INTRODUCTION: HISTORY AND HISTORIOGRAPHY

Richard Kirwan (1733-1812), Irish natural philosopher and polymath, contributed to a wide array of domains such as mineralogy, meteorology, geology and metaphysics, but especially to chemistry, for which he is best known.376 From 1777 to 1787 Kirwan resided in London; in 1780 he became a Fellow of the Royal Society and was awarded, for his work on chemical affinities, the Society’s most prestigious prize, the Copley Medal.377

During his London years he became increasingly engaged in pneumatic chemistry, exhibiting a particular concern for the phlogistic cause. With the rapid evolution of events that we now recognize as the Chemical Revolution, Kirwan came to be regarded, especially by the latter half of the 1780s, as the most prominent spokesman of the phlogistic camp, a recognition that was strongly established on both sides of the

Channel.378 British chemists in general and particularly Joseph Priestley, the most prolific

376 Kirwan is also known for his geological debate with James Hutton. Scott (1981), p. 143, fn. 12. 377 See Gillispie (1970-80), VII, pp. 387-390. Scott’s entry in the DSB arises from his doctoral research, which comprises a unique study of Kirwan’s life and work and contains extensive and valuable information. Scott (1979). Further details on Kirwan’s life and work can be gleaned from Reilley and O’Flynn (1930); Partington, (1961-70), Vol. III, pp. 660-671. For the best account of Kirwan’s work on chemical affinities and its relation to the wider context of eighteenth-century chemistry see Kim (2003), esp. pp. 268-277. 378 The ‘phlogistic camp’ refers broadly to British pneumatic chemists who subscribed, during the 1780s, to phlogistic tenets. Most notable as well as pertinent to the ensuing discussion are Joseph Priestley and Adair Crawford, who shared several fundamental beliefs concerning the constitution of airs (C. W. Scheele, who held different ideas, was also a devout phlogistian and figures prominently throughout the course of this study); Joseph Black and Henry Cavendish are notable,

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among contemporary British pneumatic phlogistians, as well as Lavoisier and his collaborators, considered Kirwan as the leading authority on phlogistic matters.379

Kirwan’s work on the theory of phlogiston, carried out over the better part of that climactic decade, reached its final form in what is his best-known tract: An Essay on Phlogiston and the Constitution of Acids (1787), which is dealt with more extensively later, in chapter 4.

Neither its original title nor the increasingly acknowledged importance of its originator betrays the full significance of Kirwan’s Essay. Only the cumbersome title of its final 1789 version captures some of its breadth: Essay on Phlogiston and the Constitution of Acids, to which are added Notes […] annexed to the French Edition of this Work; by

Messrs. de Morveau, Lavoisier, de la Place, Monge, Berthollet, and de Fourcroy. With

Additional Remarks and replies By the Author (hereafter: Essay). This list-like header represents an excited two-year long process. Kirwan’s 1787 initial version of the Essay was received with unprecedented interest on the continent. It was translated into French by

Mme. Lavoisier, then submitted to her husband and his colleagues, and published with too, although their particular association with phlogistic thought during this transition period is more problematic and difficult to ascertain; additional figures, of slighter repute, are James Keir and William Nicholson. 379 This is best signalled by the Lavoisians’ detailed responses to Kirwan’s Essay on Phlogiston, in which their collaborator (and translator), Mme. Lavoisier, wrote about Kirwan that “Among the philosophers who have not yet adopted the new doctrine, he is certainly one of those who is the most capable of producing uncertainty in the minds of such persons as decide by authority.” Kirwan (1789), p. xiv. The term ‘Lavoisians’ is usually taken to include Lavoisier’s closest collaborators, C. L. Berthollet, A. F. Fourcroy and Guyton de Morveau, his co-authors to the Method of Chymical Nomenclature. Berthollet & Fourcroy & de Morveau (1788). Lavoisier had also conducted significant collaborations with Pierre-Simon Laplace and with Gaspard Monge. This group is sometimes named the Arsenal group, after their regular place of meeting for scientific discussions. See Kim (2003), pp. 335-337. For Priestley’s acknowledgements see his post- revolutionary plea, addressed to the Lavoisians, ‘The Surviving Answerers of Mr. Kirwan’ and his reference to Kirwan’s “pretty large treatise in opposition” to the French system. Priestley (1796), pp. 33-36. This 1796 plea was reproduced four years later verbatim (and again, in 1803 ‘with additions’) in Priestley (1800), pp. x-xi; Priestley also reflects solemnly upon Kirwan’s conversion. Ibid., p. 2.

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their comments and remarks in 1788.380 This version was then re-translated into English by William Nicholson, affixed “With Additional Remarks and replies By the Author,” and re-issued in 1789, the year in which Lavoisier’s Traité élémentaire de chimie also appeared. This final version of the Essay, capturing the phlogistic debate at its climax, is a multi-layered text, as William Nicholson noted in praising the “advantages that must result from the compression of this controversy, into one small volume, by such men.”381

Although a detailed analysis of the Essay and its immediate ramifications is not the main theme of the present chapter,382 as Kirwan’s phlogistic summa and most widely acknowledged chemical work, the Essay will serve as a crucial reference point in evaluating Kirwan’s historiographic predicament in relation to key trends in the scholarship of the chemical revolution.

Overshadowed by longstanding triumphalist historiographical sensitivities,

Kirwan’s work on phlogiston has received a short shrift from interpreters of the chemical revolution; the Essay has been generally depicted as a resourceful yet belated attempt to resuscitate a deeply troubled phlogiston theory. On this account, Kirwan’s function in the

1787-89 controversy amounted to little more than a post-mortem defense. This view has been buttressed by Kirwan’s own sudden capitulation and abandonment of phlogistic chemistry in 1791, only four years after the Essay’s inaugural publication, thus embellishing perceptions of the Essay as one of the final stages in an otherwise impending

380 For biographical details on Mme. Lavoisier and her particular involvement in this project as translator see Duveen (1953), pp. 14-16; Kawashima (2000), pp. 235-263. 381 Kirwan (1789), p. vi. 382 The Kirwan-Lavoisians dispute, as arising from the dynamics and rhetoric of the Essay, is dealt with in greater detail in chapter 4.

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process of conversion to the new chemistry.383 Reduced to an instance of acuity in the chronicles of phlogiston’s demise, little attention has been paid to Kirwan’s phlogistic work. While his theory of phlogiston has been subjected to some analysis, we still know little about the circumstances of its emergence and its evolution vis-à-vis the wider contemporary phlogistic-pneumatic sphere and community.384

The collapse of the phlogistic world-view has long since been one of foremost motifs in the historiography of the chemical revolution.385 Traditionally evaluating phlogistic thought and practice against the background of Lavoisier’s programmatic work, we have grown accustomed to interpreting most phlogistic endeavors, particularly those dating from the 1780s, as essentially defensive ventures. Although Kirwan’s Essay is almost an exemplar of a quintessential phlogistic defense, it is Priestley’s name and heritage that loom large in this context.386 Kirwan’s phlogistic research—which had started during the late 1770s, was officially introduced in 1780, culminated with the 1787-

89 controversy, and ultimately ended with Kirwan’s 1791 capitulation—got eclipsed by the forceful historiographic association between Priestley and phlogiston in the context of the chemical revolution. It is, after all, Priestley who is commonly and widely perceived

383 See, for instance, the excellent historiographic analysis: Holmes (1995), in which the author stated that by 1787, the year Kirwan’s Essay was first published, “the [chemical] revolution was consummated”; he further noted that, “By that time, the most important experimental and theoretical confrontations on which the issue hung were essentially over.” (p. 19). See also reference to Kirwan’s “reputation as a stubborn defender of outmoded causes.” Scott (1981), p. 143; Cf. Brock, (1993), p. 93. 384 Two notable recent exceptions are Kim (2003), pp. 379-383 and Mauskopf (2002). Both authors focus mainly on Kirwan’s research into chemical affinities and the way it informed his arguments against the antiphlogistic chemistry. 385 For the philosophical locus classicus of this view see Kuhn (1962); the historical one is Conant (1950). For a historical survey and insightful discussion concerning the historiography of the chemical revolution in the wake of Kuhn and Conant see McEvoy (2001). 386 See, for instance, Toulmin & Goodfield (1962), esp. pp. 222-228; Musgrave (1976).

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as “the most relentless opponent of the antiphlogistic theory” or otherwise “the last important defender of phlogiston.”387 Consequently, while Kirwan’s contributions to the subject have been largely overlooked, Priestley’s phlogistic perceptions, comprising little more than “scattered responses to particular observations… not connected into a broader framework,” have been at the centre of numerous evaluations, providing a rich source for scholarly contention and debate.388

Priestley, as we have seen, was the most prolific pneumatic practitioner of his generation, discovering and isolating, single-handedly, an unmatched number of new airs.

Most notably, he was the first to isolate dephlogisticated air (oxygen) by way of what is commonly considered as one of the most crucial experiments of the chemical revolution.389

387 Levere & Turner (2002), p. 196; Siegfried (1988), p. 35. 388 Holmes (2000), p. 748. In a different study, inspired by “Ferdinando Abbri’s important study of the chemical revolution, Le terre, l’acqua, le arie,” Holmes suggested a revisionist portrayal of the commonplace historiographic personae of Priestley and Lavoisier, undermining the received view based on “Priestley’s reputation as a brilliant experimentalist and Lavoisier’s reputation as a lesser experimentalist, but greater theorist.” Holmes’s study draws on an original reading of the historical actors’ rhetorical devices and reportage, emphasizing how during the late 1770s and early 1780s, far from perceiving himself as leading a revolution, Lavoisier acknowledged Priestley’s eminence, while claiming the status of “only an able participant in a broader revolution brought about by the new pneumatic chemistry.” Holmes (2000b), pp. 75-76, 80; see also Abbri (1984). For various, often divergent, approaches to Priestley’s phlogistic endeavors see, for instance, Schofield (1964); McEvoy (1987); Verbruggen (1972). McEvoy, for example, mentions both Priestley and Kirwan in the context of “phlogistic defences” but Kirwan’s efforts are depicted as mere “suggestions,” which Priestley had briefly “endorsed” and then “rejected”; furthermore, Kirwan’s identification of phlogiston with inflammable air is rendered as a sign of the theoretical frailty of phlogistic outlooks: “Lavoisier’s pragmatic definition of an element as an end product of analysis… did not rob the principle of phlogiston of its substantive identity… [but] it did influence them [phlogistians] in their desire to identify it with a specific [isolable and weighable] substance.” McEvoy (1988), pp. 200-201. 389 See, for instance, Toulmin (1957). Other momentous experiments in the chemical revolution include the decomposition and synthesis of water, a controversial subject that has drawn substantial scholarly attention. Contention about who discovered the compound nature of water occurred in two phases. During the first phase, in the 1780s, the claimants to the discovery (Lavoisier, Cavendish and James Watt) produced the work on which their claims were based. This phase of the dispute was relatively short, although it was part of the larger debates surrounding the Chemical

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Finally, he was possessed of a combative and nonconformist polemical character, which found expression in his own well-publicized post-mortem phlogistic campaign.390

Whereas Priestley’s SER was embedded in a phlogistic framework for close to three decades and Priestley remained a phlogistonist until the day he died, Kirwan’s phlogistic involvement lasted for slightly over a decade and ended with his quiet capitulation.391 Like most contemporary pneumatic chemists, Kirwan relied extensively upon Priestley’s experiments and observations. Yet as far as phlogistic chemical theory was concerned,

Kirwan’s contributions surpassed those of Priestley, who had neither forged any systematic doctrine of phlogiston nor ever exhibited any particular wish to do so.392 In fact, as soon as

Kirwan’s doctrine of phlogiston established its dominance, around the mid 1780s, Priestley not only accepted and recommended it but also kept acknowledging it by referring to

Kirwan’s Essay and contributions.393

An elaboration of Kirwan’s interactions—intellectual, theoretical, experimental— with the surrounding pneumatic community will not only provide the missing context but will also spell out the differences and contrast, thus setting apart and emphasizing

Kirwan’s own appropriations, reformulations and innovations as part of his SER. Tracing

Kirwan’s debts and delineating his original contributions will help in reconstructing his

Revolution. The second phase of controversy (1830s-40s), however, consisted in heated exchanges between followers of Watt and of Cavendish, respectively. See Miller (2004). 390 See Conlin (1996). 391 On Kirwan’s 1791 ‘conversion’ see Mauskopf (2002), pp. 202-204. 392 This point has been most recently argued by Holmes, who suggested a reformulation of our understanding of Priestley’s phlogistic interests by situating them within a ‘novel’ pneumatic framework that Priestley himself established and which did not owe its origins to Stahlian precepts; within this framework, Priestley’s theoretical commitments to phlogiston were secondary and loosely defined. Holmes (2000a). 393 For Priestley’s acceptance of Kirwan’s doctrine of phlogiston, on theoretical as well as experimental grounds, see: Priestley (1783), esp. pp. 399-414.

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work on phlogiston and will uncover the complex interaction between continuity and discontinuity in pneumatic phlogistic SERs in the context of the Chemical Revolution.

In March 1782 Priestley addressed a letter to Josiah Wedgwood, his fellow- member at the Birmingham Lunar Society, in which he wrote:

Before my late experiments phlogiston was indeed almost given up by the Lunar Society, but now it seems to be reestablished. Mr. Kirwan in a letter I have received from him this day, says that he has given in a paper to the R. Society, to prove, from my former experiments that phlogiston must be the same thing with inflammable air, and also that dephlogisticated air and phlogiston make fixed air.394

These lines capture the two pillars upon which Kirwan’s phlogistic approach and SER revolved: the doctrines of phlogiston-as-inflammable-air and of fixed air. Briefly stated, the former doctrine follows from the assumption that phlogiston can exist in two states: solid and gaseous. When found in combination with other substances, phlogiston assumes a concrete state and cannot be isolated or exhibited alone; but when it is found in an aeriform or gaseous state, it is “the same thing with inflammable air,” a distinct and isolable kind of air. According to the second opinion, the product of all phlogistic processes is fixed air, which proceeds from the union of dephlogisticated air and phlogiston; its reabsorption by calcined metals, for instance, explains their weight gain. It will be to these two core principles that Mme. Lavoisier will refer, six years later, as the

“ingenious modifications he [Kirwan] has introduced into the theory of phlogiston.”395

Judged independently, Kirwan’s “ingenious modifications” may seem as little more than resourceful considerations meant to allow for a reconciliation between traditional

394 Schofield (1966), pp. 206-207. 395 Kirwan (1789), p. xv.

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phlogistic perceptions and the growing body of chemical observations and discoveries.

When set, however, against the background of preceding pneumatic debates, ideas and matter theories, an understanding of Kirwan’s SER will afford us an invaluable glimpse into the evolution of phlogistic thought in the pneumatic context during the 1770s and

1780s, which saw the unprecedented rise of the chemistry of airs. What follows is a reconstruction of implicit pneumatic phlogistic perspectives out of which Kirwan’s phlogistic outlook had emerged. I demonstrate the way phlogistic thought and practice evolved out of debates related to the constitution of airs as well as other pneumatic entities, such as heat and light, and the nature of Kirwan’s appropriation of these ideas as part of his

SER. Any attempt to evaluate Kirwan’s “modifications” requires an understanding of what has been subjected to modification, how and under what theoretical and practical circumstances. Since the dynamics and development of Kirwan’s contributions to phlogistic chemistry coincide chronologically and ideologically with the Chemical

Revolution—while his version of phlogistic theory comprised the leading reaction against the Lavoisians—their contextualization promotes an appraisal of neglected features of phlogistic-pneumatic chemistry, opening paths for a richer understanding of the revolutionary nature of this Revolution. Uncovering the origins of Kirwan’s “ingenious modifications”—innovations and renovations alike—sheds light on some of the leading yet controversial themes in the historiography of the Chemical Revolution, facilitating a finer understanding of the dialectics between continuities and discontinuities and, on a more general level, between the reformative and the revolutionary.396

396 The continuity vs. discontinuity debate is open-ended. Cf. Gough (1988); McEvoy (1988).

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PHLOGISTIC TRANSMUTATIONS AND THE METAPHYSICS OF PNEUMATIC ENTITIES

As we have seen, the nature and scope of Priestley’s scientific work has been the subject of numerous historiographic disputes. Yet no reconstruction of pneumatic thought and practice—particularly in the British context of the latter third of the eighteenth- century—can exclude reference to Priestley’s pioneering work in the field. Insistently true to the spirit conveyed by the title(s) of his multi-volume publication(s), Experiments and

Observations on Different Kinds of Air, Priestley, in accord with his SER, was cautious when it came to theorizing. While his writings abounded with experimental reports, theoretical considerations were few and far between. In 1775, however, three years after his inaugural pneumatic publication, he wrote:

Upon the whole, I think, it may safely be concluded, that the purest air is that which contains the least phlogiston: that air is impure (by which I mean that it is unfit for respiration, and for the purpose of supporting flame) in proportion that it contains more of that principle; and that there is a regular gradation from dephlogisticated air, through common air, and phlogisticated air, down to nitrous air; the last species of air containing the most, and the first-mentioned the least phlogiston possible, the common basis of them all being the nitrous acid; so that all these kinds of air differ chiefly in the quantity of phlogiston they contain.397

This intriguing passage embodies a chemical-phlogistic pneumatic scheme, at the heart of which lie several key principles. First, the notion that all airs share a common basis, or base as it were. Secondly, that the species of air is directly dependent upon the quantity of phlogiston that is combined with this base. Thirdly, that the various airs included— dephlogisticated, common, phlogisticated and nitrous—should be perceived as distinct

397 Priestley (1775a), p. 392.

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steps, or “gradation[s],” within a pneumatic sequence. (Table 1:A).398 Fourthly, given the correlation between the “proportion” of phlogiston combined and this “gradation,” the air’s specific placement within the sequence implies its purity, or, its degree of fitness “for respiration, and for the purpose of supporting flame.” Fifthly, that the various airs included are variations of each other and are subsequently transmutable into each other.

By inference, since such pneumatic transmutations are occasioned by increases or decreases in phlogistic content, aerial phlogistications and dephlogistications are essentially transmutational processes.399

Priestley’s contemporary, the Swedish pharmacist Carl Wilhelm Scheele, conducted similar pneumatic inquires throughout the 1770s and had isolated dephlogisticated air, (to which he referred as empyreal or fire air) sometime early in the decade. But whereas Priestley pursued facts quickly and published speedily, producing voluminous pneumatic reports, Scheele published only one treatise.400 In 1777, following a two-year-long delay, during which Scheele waited for Torbern Bergman’s promised preface, his Chemische Abhandlung von der Luft und dem Feuer appeared. The work, which drew the immediate attention of the most eminent contemporary pneumatic

398 It should be noted that ‘Table 1’ represents a comparative conceptualization of what I have denominated ‘pneumatic phlogistic sequences’—i.e. these ‘sequences’ do not occur, as such, in the writings of the figures discussed. Rather, they represent a conceptual apparatus extracted and gleaned from the respective texts. In this context, the author owes a substantial intellectual debt to a little known work, which although devised as part of a different argument, exhibits a similar methodological approach. Langer (1971). 399 I use ‘transmutation’ to denote the implicit view, endorsed by contemporary phlogistic pneumatic practitioners according to which different airs (or other pneumatic kinds) corresponded to various degrees of phlogistication of a generic pneumatic entity. This process is shown to have followed, theoretically and practically, distinct sequential patterns. 400 Priestley (1790), p. xvii.

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chemists, was translated into English by J. R. Forster and republished in 1780 as Chemical

Observations and Experiments on Air and Fire.401

Scheele’s SER drew largely upon a phlogistic framework and he shared some of

Priestley’s fundamental convictions. Yet their overall conceptual perspectives differed radically. Priestley’s research was motivated primarily by his interest in the constitution of atmospherical air and the nature of the changes it underwent during different pneumatic processes such as combustion, calcination, respiration, vegetation and putrefaction.402

Scheele approached the subject with a different goal in mind: his main interest was to provide a chemical account for the constitution of fire itself. Having noted that pneumatic chemistry “shews us, that Fire, that is so wonderful, cannot be generated without Air,” he declared that his treatise “ought to be considered only as an Essay towards the Chemical

Doctrine of Fire.” In particular, it was meant to provide evidence “that a kind of Air subsisting in our atmosphere is a true constituent part of Fire and materially contributes to the existence and support of flame,” and was accordingly named “empyreal Air (Fire

Air).”403

Despite the obvious metaphysical implications of Scheele’s SER, he justly emphasized his experimental commitments, holding that “there are evident Experiments that speak for me; Experiments which I have many times repeated… [and which have]…attained my view of coming as close as possible at the knowledge of Fire.”404

401 Scheele (1780). 402 Priestley (1772a). 403 Scheele (1780), pp. vii-viii. 404 Scheele (1780), p. viii.

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Bergman, the author of the preface, affirmed the far-reaching implications of Scheele’s work:

[Scheele] instructs us not only about light, but also about fire, whose explication has hitherto been the crux philosophiae… Heat, Fire, and Light are in regard to the elementary principle, the same with good Air and phlogiston; but their proportion and perhaps the manner of their composition, cause the great difference. Phlogiston seems to be a real elementary principle, which enters the chief part of substances, and adheres to them most obstinately. There are several means to separate it more or less perfectly: Of those known substances, good Air is most active405

Like Priestley, Scheele was intrigued by the phenomenon of aerial diminution, observed in various pneumatic processes. He noted that “substances either undergoing putrefaction or decomposition by Fire, diminish or as it were absorb part of the air.”406 A diminution in aerial volume had been observed in the mixture of air with several substances such as sulphur (in limewater), volatile liver of sulfur, nitrous air, etc.407 Drawing upon the “well known” experimental supposition according to which air “deprives” bodies of their phlogiston—their “inflammable part”—Scheele assumed, in line with Priestley, that “in the transition of what is inflammable principle into the Air, a considerable part of the Air is lost” and that the “inflammable principle is the sole cause of this effect.”408 In general, then, when phlogiston is released into the air it will bring about its diminution. Scheele further concluded that, “air is composed of two different fluids”: one that tends to attract phlogiston and another that does not.409 The former was designated “empyreal air” while

405 Scheele (1780), pp. xxxviii-xl. 406 Scheele (1780), p. 6. 407 Scheele (1780), pp. 10-12. 408 Scheele (1780), pp. 13-14. 409 Scheele (1780), p. 16.

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the latter “foul air [literally corrupted air],” since it was “unserviceable for the fiery phenomenon.”410

Scheele was interested in explaining what became of this fire air after its union with phlogiston.411 It is in this specific context that his SER assumed an unexpected interpretive dimension: he set out to “prove, that by the union of air to the inflammable principle, a compound is formed, so subtle as to pass through the fine pores of the glass, and disperse all over the air.”412 Scheele had carefully examined the distillation of nitric acid from sulphuric acid and niter, while paying particular attention to the changing intensity in the redness of the fumes produced in relation to the heat applied.413 He surmised that, “during each union of the phlogiston with air, heat is generated; and consequently that heat is a compound of that [fire] air which makes the third part of common air” and of “an inflammable substance.”414 Scheele interpreted the distillation process in the following manner:

This heat it is, which during the distillation of concentrated acid of nitre is decomposed, and resolved into its integrant parts. This owes its existence to the fire employed in the distillation; at first it is composed of air, (without which no fire can be imagined,) and of the phlogiston of the coals; it penetrates the cuppel [sic], the sand and retort, where it meets with a substance attracting more powerfully the phlogiston, than the air does which is united with it, consequently heat is decompounded; by which means the acid of nitre is tinged of a deep colour; the air which had been divided into incomprehensibly minute parts, reassumes its former quality; it is pushed into the receiver by the concomitant acid, becomes more elastic by heat, where it has opportunity again to attract phlogiston; and since in the

410 Scheele (1780), p. 35. 411 Scheele (1780), p. 16. 412 Scheele (1780), p. 26. 413 Scheele (1780), pp. 25-31. 414 Scheele (1780), pp. 32-33.

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receiver a greater proportion of this kind of air is present, than in common air, it is no wonder, that the flame there is stronger and brighter.415

The most striking consequence, then, is that heat is to be considered a compound of fire air and phlogiston; it originates from the union of “air… and the phlogiston of the coals” and subsequently enters into the distillation chamber, where it is “decompounded”—stripped of its phlogiston. The resulting air “reassumes its former quality,” regains its elasticity and reunites with more phlogiston, which in turn generates a “stronger and brighter” flame.

Although Scheele admitted that, “this opinion ought to appear to my readers as strange, as it did in the beginning to me,” he concluded that, “it is not a mere hypothesis, but one of the clearest truths.”416

As part of Scheele’s effort to construct a “Chemical Doctrine of Fire,” the strength and brightness of the flame were regarded as phenomena of particular significance.

Having established, experimentally and theoretically, the nature of “the constituent parts of heat, and likewise those of Air,” he proceeded to incorporate light. Notably, Scheele presupposed the materiality of all principles in his system. “Phlogiston” he considered to be “a substance… which always supposes some weight.”417 Similarly, he had no qualms

“about light being a body, in the same manner as heat,” although they were to be regarded as “two separate entities.” This followed from his reasoning that “light, though ever so much concentrated, cannot produce any heat in the Air; consequently I cannot persuade myself that light is pure phlogiston”; yet “it is not to be considered as heat only,” since “its

415 Scheele (1780), p. 33. 416 Scheele (1780), pp. 33-34. 417 Scheele (1780), p. 26.

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integrant parts are made up in a proportion entirely different from that of heat.”418 Finally, linking air, fire, heat and light, Scheele held that:

if empyreal Air is composed with more phlogiston than is necessary for producing heat, radiant heat is produced; if some very little phlogiston be added, the property discovered in radiant heat is then increased and light is produced… I therefore am of opinion that each particle of Light is nothing more than a subtle particle of empyreal Air, which is more charged with phlogiston than an equally subtle particle of heat.419

Regarding heat, he remarked that, “with a small addition of phlogiston it produces light; and with still more, the well known inflammable air.”420 (Table 1:B).

Evidently, the pneumatic explanations of Priestley and Scheele differ fundamentally in content and particulars. Yet both explanations share a striking formal similarity. Like Priestley, Scheele proposed an explanation based on a pneumatic phlogistic sequence, founded upon the increase and decrease of phlogiston. Moreover, both sequences consisted of “regular gradation[s]” and conformed to the same implicit principles of pneumatic transmutability. Finally, in both sequences, the first step—i.e. the least phlogisticated pneumatic entity—corresponded to the same entity: “dephlogisticated air” and “empyreal air” according to Priestley and Scheele, respectively. This conceptual semblance is all the more striking in light of the fact that Scheele had formulated most of his views without being aware of Priestley’s findings, while Priestley did not know anything of “Scheele’s work” prior to its “delay[ed]” publication.421 With fire air comprising the first identifiable pneumatic step, Scheele’s sequence consisted of four

418 Scheele (1780), pp. 77, 97. 419 Scheele (1780), pp. 97-99. 420 Scheele (1780), p. 178. 421 Scheele (1780), pp. viii, xl.

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separate steps, corresponding to four distinct entities involved in pneumatic processes: from the least phlogisticated empyreal air to the most phlogisticated inflammable air, with heat and light as intermediary steps. Recalling Priestley’s sequence, “dephlogisticated air” was followed by the common, phlogisticated and nitrous airs. The chief conceptual discrepancy between the two pneumatic sequences reflects the divergent motivations and metaphysical commitments of the authors. Since Priestley’s observations underscored the link between combustion and respiration, an air’s fitness “for respiration, and for the purpose of supporting flame” was of leading significance in formulating the principle according to which, within the sequence, “the purest air is that which contains the least phlogiston [and] that air is impure… in proportion that it contains more of that principle.”422 Scheele, on the other hand, with his mind set on providing a “Chemical

Doctrine of Fire,” emphasized the importance of heat and light, which followed his fire air, as the second and third steps in his sequence. He assumed that light was phlogisticated heat and that heat was composed of fire air and phlogiston.

In his Dissertation on Elective Attractions Bergman presented the most elaborate table of chemical (elective) affinities available at the time. Phlogiston was situated at the head of the 36th column and heat figured at the head of the 37th. In the entry relating to

Column Thirty-seventh, the Matter of Heat, Bergman explained:

The chief opinions now prevailing concerning the matter of heat may be referred to three systems. First, some consider light itself as elementary fire… it may be fixed in bodies, and enter into their composition as a proximate principle; in which state it is denominated phlogiston. The great simplicity of this hypothesis recommends it; but it can scarce maintain its ground, since it has been shown that uncombined phlogiston is nothing but

422 Priestley (1775a), p. 392 (see fn. 397).

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inflammable air… Secondly, Others argue, that elementary fire, which in a state of liberty occasions warmth, is not only different from phlogiston, but so opposite that one every where expels the other, at least in part. Air during phlogistication gives out much specific fire, which, when free, heats, calcines, causes ignition, etc… The third system is that of my sagacious Mr Scheele, who thinks that the matter of heat is not simple, but compounded of phlogiston and vital air, closely combined, and that light consists of the matter of heat, with an excess of phlogiston.423

The sense of theoretical diversity, emanating from this passage, is suggestive of the prevalent strands of phlogistic-pneumatic SERs during the late 1770s and early 1780s.

Having already discussed the “third system,” that of the “sagacious Mr Scheele,” we turn to the other two perspectives mentioned. According to the “first” view light is recognized as “elementary fire” (heat) and when it is bound with other substances—“fixed in bodies”—it is considered to be phlogiston. This perception brings Pierre Joseph

Macquer’s ideas to mind, advanced earlier in the century. Identifying light with phlogiston, Macquer wrote in 1764 that “the Matter of the Sun, the Phlogiston, Fire, the

Sulphureous Principle, the Inflammable Matter, are all of them names by which the

Element of Fire is usually denoted.” He complained, nevertheless, about the lack of an

“accurate distinction… between the different states in which it exists; that is, between the phenomena of Fire actually existing as a principle in the composition of bodies, and those which it exhibits when existing separately and in its natural state.”424 Interestingly, in

1775, employing “deductions from electrical phenomena,” Priestley entertained a similar notion, arguing that, “it is probable that all light is a modification of phlogiston… Light

423 Bergman (1785), pp. 231-234. 424 Macquer (1764), p. 7. During the latter third of the eighteenth-century light was considered by various chemical practitioners to be a chemical-pneumatic identity; although Priestley’s reasoning differed from Scheele’s he also accorded light such a status. See Boantza (2006).

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and phlogiston are the same thing, in different forms or states.”425 Despite Bergman’s criticism, this opinion held great currency among the French chemists, including the

Lavoisians and has influenced Lavoisier’s own, somewhat obscure, formulation of the relation between heat and light in pneumatic processes.426

During the height of the chemical revolution, Lavoisier’s close collaborator,

Antoine François Fourcroy advanced the following, surprisingly conciliatory, opinion:

that the matter of fire or of heat, which Mr. Lavoisier admits in pure air, whose disengagement is supposed by him to be the cause of the bright flame in combustion, can be nothing else than the phlogiston of Stahl, or the fixed light of Macquer; and that all chemists are of course agreed that it exists.427

In seeking to downplay the break between traditional phlogistic views and Lavoisier’s revisionist approach, Fourcroy highlighted the metaphysical conformity surrounding the absolute existence of a “matter of fire or of heat,” be it “the phlogiston of Stahl, or the fixed light of Macquer.” The only difference between the camps is rendered by Fourcroy almost as an afterthought: “Lavoisier admits [the existence of this principle] in pure air,” and not as a constituent of all inflammable bodies. Notably, this latter observation—of phlogiston being a component of all inflammable bodies—comprises perhaps the one single most important phlogistic metaphysical commitment, commonly found in all phlogistic versions and doctrines, across various domains of application and practice.

Bergman, as seen, rejected Macquer’s view that fire in its ‘natural state’ is the same as the

425 Priestley (1775b), 280. 426 In the Traité Lavoisier wrote: “in the present state of our knowledge, we are unable to determine whether light be a modification of caloric, or if caloric be, on the contrary, a modification of light… [but] we ought provisionally to distinguish, by distinct terms, such things as are known to produce different effects.” Antoine Lavoisier (1790), pp. 4-6. 427 Fourcroy (1788), I, p. 142.

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“Matter of the Sun, of Light, and of Heat”428 on the grounds that “it has been shown that uncombined phlogiston is nothing but inflammable air.” In a similar vein, Fourcroy noted that, “the doctrine most generally received in Britain is, that inflammable air is either pure phlogiston, or contains phlogiston nearly pure.”429 We can glean some clues on the evolution of this distinctly Kirwanian dictum from what Bergman had referred to as the second of the “three systems”—the idea that “elementary fire… is not only different from phlogiston, but so opposite that one every where expels the other.”

THE PHLOGISTIC CONSTITUTION AND ROLE OF HEAT

The complete title of the 1780 English edition of Scheele’s treatise reads: Chemical

Observations and Experiments on Air and Fire… With a Prefatory Introduction by

Torbern Bergman… To Which are Added Notes, By Richard Kirwan, With A Letter to him from Joseph Priestley. Kirwan’s “notes,” which were commissioned by Priestley,430 mark

Kirwan’s first public statement pertaining to the doctrine of phlogiston. Kirwan’s critical assessment of Scheele’s observations affords a unique glimpse at the state of phlogistic pneumatic knowledge during a period when the chemical study of airs was at its peak. The year 1780 can be conveniently considered as a chronological midpoint, between Priestley’s inaugural work of the early 1770s and Lavoisier’s publication of his Traité in 1789.

Two significant features of Kirwan’s SER are immediately discernable. He began by declaring his allegiance to “Dr. Priestley, to whom, indeed, the Doctrine of Air owes

428 Macquer (1764), p. 7. 429 Fourcroy (1788), I, p. 142. 430 Scheele (1780), p. 250.

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more… than to any one who has yet appeared” while pointing out “how little he [Priestley] deserves the appellation of a mere Experimenter,” given the magnitude of his pneumatic

“theoretical discoveries.”431 Kirwan was equally quick to praise Adair Crawford’s (1748-

1795) revolutionary discoveries.432 He admitted that Scheele could not have known about these crucial findings, “Dr. Crawford’s Treatise being much posterior to his.” At the same time, Kirwan was overtly critical of Scheele, maintaining that,

There never was perhaps a more signal proof of the incapacity of the human understanding to make any important discovery, without passing through the intermediate steps, than the attempt of our Author to penetrate into the very essence of fire, without availing himself, or perhaps being acquainted with the intermediate discoveries of Fahrenheit, Black, and Crawford.433

Crawford’s pneumatic observations had a remarkable impact on contemporary pneumatic research, and on phlogistic perceptions in particular. The way in which Kirwan drew upon

Crawford’s work, in formulating his own contributions to the subject, is of particular significance to the present discussion. This connection and influence, although largely overlooked by modern commentators, can hardly be overstated. To anticipate, Kirwan’s phlogistic doctrine, which would emerge as the strongest alternative to Lavoisier’s theory of combustion and acidity, emanated—against the background of his critique of Scheele’s views on the ontology of fire—from a unique amalgamation of Priestley’s basic pneumatic sequence and Crawford’s radical formulation of the relation between phlogiston and heat, which stemmed, in turn, from a physiologically-oriented line of research.

431 Scheele (1780), p. 223. 432 For biographical details on Crawford see Partington (1961-70), III, pp. 156-157. 433 Scheele (1780), p. 196.

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“Dr. Crawford’s Treatise,” alluded to by Kirwan, was the Experiments and

Observations on Animal Heat, and the Inflammation of Combustible Bodies published in

1779, two years after the publication of Scheele’s inaugural German edition of the

Chemical Observations.434 The significance of this pioneering work—in particular its influence on the phlogistic study of airs in the 1780s—has not been adequately recognized.435 Crawford, like Scheele before him, was interested in the relation between phlogistic pneumatic processes such as combustion, calcination, respiration, etc., and the evolution of heat. Crawford’s explanation, however, which caught Kirwan’s attention, was innovative and fundamentally different from the one put forth by Scheele. Typically,

Crawford derived his theoretical and experimental inspiration from the largest and most elaborate repository of pneumatic observations available at the time, those of the indefatigable Priestley, who by 1777 had already published the first three volumes of his

Experiments and Observations.436 By the summer of the same year, Crawford “began the first experiments ever performed on the specific heats of gases… [the results of which were] then applied to the problem of animal heat.”437 Crawford traced another source of

434 Crawford (1779). The second edition of this essay was published in 1788, under the same title “with very large additions,” and was dedicated to Kirwan “as a mark of respect and esteem, by his most sincere friend, and obliged humble servant, the author. [A. Crawford].” The first 1779 edition consisted of 128 pages; the second edition consisted of 511 pages. 435 Some exceptions, mostly descriptive, include Mendelsohn (1964) and Partington and & McKie (1938), esp. pp. 345-350. See also McKie & Heathcote (1975), passim. 436 The three volumes were published in 1774, 1775 and 1777 and were followed by three additional volumes published in 1779, 1780 and 1786, respectively. The latter three were entitled Experiments and observations relating to various branches of natural philosophy; with a continuation of the observations on air. All of Priestley’s pneumatic volumes went through numerous editions. 437 Donovan (1975), p. 273.

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major influence to the time when he “attended the chymical Lectures of the learned and ingenious Dr. Irvine of Glasgow.”438

In line with Priestley, Crawford believed that respiration and combustion were chemically analogous processes. Consequently, given his physiologically informed focus on the role of heat in pneumatic reactions, his research goal was to ascertain “the true source, from whence the heat of animals, and the heat which is produced by the inflammation of combustible bodies, is derived.”439 Crawford observed that only those animals that have lungs and breathe in common air in large quantities “have the power of keeping themselves at a temperature considerably higher than the surrounding atmosphere.” The larger the animals’ “respiratory organs,” the warmer they are. Their actual “degree of heat,” moreover, seemed “proportionable to the quantity of air inspired in a given time.” Translating these observations into pneumatic terms, Crawford argued that common air is richer in “absolute heat”—the actual quantity of heat the air contained— than air that had been “expired from the lungs of animals.” In fact, Crawford held that the more life supporting and hence pure an air was, the larger the quantity of heat it retained, a principle which echoes Priestley’s notion, relating the purity of air(s) to their phlogistic content. To prove this conjecture, Crawford ventured to “consider the nature of the change which the air undergoes in the lungs.” Yet unlike Priestley before him, Crawford regarded the production of fixed air in respiration as a phenomenon of major importance. In

438 Crawford (1779), 17, (in fn). William Irvine (1743-1787) studied medicine and chemistry under Joseph Black (1728–1799) and assisted him in his first experiments on latent heats. In 1766 he was appointed as medical lecturer at the University of Glasgow, a position he held until his death. Donovan (1975), pp. 265-266. 439 Crawford (1779), p. 18.

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particular, it seemed to him to depend “upon a change, which the atmospherical air undergoes in the lungs.”440 He further noted:

Air is altered in its properties by phlogistic processes, and though many of these processes are totally different from each other, yet the change produced in the air, is in all cases, very nearly the same. It is diminished in its bulk. It is rendered incapable of maintaining flame, and of supporting animal life. And, if we except a very few instances, where the fixed air is absorbed, it universally occasions a precipitation in lime-water. We have therefore reason to believe, that there is no instance of a phlogistic process in nature, which is not accompanied with the production of fixed air.441

It is the last sentence of this passage that distinguishes Crawford’s view from those adduced by his predecessors. He asserted that fixed air was an inseparable part of all

“phlogistic process[es],” but also that it “is, in these [pneumatic-phlogistic] processes, produced by a change in the atmospherical air.” Conceptually, then, Crawford introduced fixed air into what could be otherwise viewed as a phlogistic sequence akin to Priestley’s.

But whereas Priestley suggested that upon phlogistication common air would turn into phlogisticated air alone, Crawford maintained that during pneumatic processes such as

“respiration, atmospherical air is converted into fixed air and phlogisticated air.”442 (Table

1: C).

440 Crawford (1779), pp. 31-32. 441 Crawford (1779), pp. 32-33. 442 Crawford (1779), p. 34; italics mine. Further on Crawford is somewhat more explicit, claiming that, “in the process of respiration, atmospherical air is converted into fixed air” without mentioning the presence of phlogisticated air (p. 69), by that he meant that the pneumatic transmutation at hand is of common air into fixed air. Dephlogisticated air would be invariably present as part of the aerial mixture. This outlook presumes that further phlogistication of common air would yield, as Priestley suggested, phlogisticated air. Partington and McKie argue along similar lines in interpreting Crawford, thus emphasizing the conceptual underpinning: “Phlogiston and pure air combine to form fixed air; the dephlogisticated air is only separated from the atmospheric air.” Partington and McKie (1938), p. 347.

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Degree of Phlogistication / Pneumatic Entity Least………………………………………………………………………Most A Priestley Dephlogisticated Common Air Phlogisticated Nitrous Air (NO) (1775) Air (O2) Air (N2) B Scheele Fire Air (O2) Heat Light Inflammable Air (1777) (H2) C Crawford Dephlogisticated Atmospherical -Fixed Air (CO2) Nitrous Air (NO) (1779) Air (O2) Air -Phlogisticated Air (N2) D Kirwan Dephlogisticated Fixed Air (CO2) Phlogisticated Nitrous Air (NO) (1780) Air (O2) Air (N2) Table 1. Pneumatic-phlogistic sequences: a comparative overview (the modern formulae, although theory-laden, are included as they add a dimension of representational uniformity to the eighteenth century chemical nomenclature).

We have mentioned Macquer’s dissatisfaction with the lack of a proper distinction

“between the phenomena of [fixed] Fire… and those which it exhibits when existing separately and in its natural state.” More than two decades later, Crawford revealed similar concerns: “The words heat and fire are ambiguous,” he complained, “heat in common language, has a double signification,” for it implies a sensation as well as a quality or substance. Professedly influenced by “Dr. Irvine of Glasgow,” Crawford distinguished between “absolute” and “sensible” heat. “It appears,” he argued,

that absolute heat expresses that power or element, which, when it is present to a certain degree, excites in all animals the sensation of heat; and sensible heat expresses the same power, considered as relative to the effects which it produces. Thus we say, that two bodies have equal quantities of sensible heat, when they produce equal effects upon the mercury in the thermometer… But it will hereafter appear, that bodies of different kinds have different capacities for containing heat; and, therefore, in such bodies, the absolute heat will be different, though the sensible heat be the same.443

443 Crawford (1779), pp. 1-2.

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Crawford distinguished between the quantity of heat contained within bodies (“absolute heat”) and “the capacities of bodies for containing heat” or, heat capacity.444 Hence two different substances, of equal weight, may share the same temperature, or “sensible heat,” yet due to differences in heat capacities, they will contain different amounts of “absolute heat.” The terminological framework employed by Crawford indeed discloses his debt to

Irvine, of whom he wrote: “it is a tribute of justice which I owe to this philosopher, to acknowledge, that the solution which he has given of Dr. Black’s celebrated discovery of latent heat… suggested the views which gave rise to my experiments.”445

Black assumed that much like other chemical entities, such as air and fire, heat could also exist in two states: fixed (combined) and free, or, according to phenomenological terminology, latent and sensible, respectively. Both Black and Irvine had used the term heat capacity to denote specific heat. Although Black remained agnostic as to the metaphysical nature of heat, he considered that latent heat was a different state of heat; this view that was later developed by, among others, Lavoisier, in the creation of his caloric theory. Irvine, on the other hand, had postulated that the relative quantities of heat contained in equal weights of different substances at a given temperature, were relative to their heat specific heats, at the same temperature. For him, the total amount of heat in a body was equal to the product of the body’s specific heat and its temperature.446 Notably,

Crawford’s definition of heat(s) lacked all reference to Black’s “latent heat,” a notion evocative of Irvine’s “solution” to this “celebrated discovery.” Following Irvine, Crawford

444 Crawford (1779), p. 16. 445 Crawford (1779), p. 17 (in fn). 446 Fox (1971), pp. 20-26; Chang (2004), pp. 64-68.

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chose to ignore the notion of “latent heat” and discussed all aspects of heat in terms of

“sensible” heat—as detected and indicated by thermometric measurement—and “absolute” heat—the total amount of heat contained in a body—supplemented by a body’s “capacity for containing heat…[being] a power inherent in the heated body.” This followed from the view that Black’s “latent heat,” the amount of heat released or absorbed by a substance during a change of state, was an ill-conceived notion. Consequently, according to

Crawford, all changes of state—and liquefaction and vaporization in particular—should be discussed in terms of changes in a substance’s heat capacity:

The capacity for containing heat may continue unchanged, while the absolute heat is varied without end… as long as its [a body’s] form continues the same, its capacity for receiving heat will not be affected by an alteration of temperature, and would remain unchanged, though the body were wholly deprived of its heat.447

Crawford’s SER and his research into heat in particular were based upon systematic experimentation and careful quantification of heat capacities. Employing the calorimetric mixture method, popularized by Black, he immersed a heated substance in an equal weight of water, for each of which the temperature was known. He then recorded the equilibrium temperature of the mixture and compared the temperature of the substance to the corresponding temperature change in the water. Using water as a standard, heat capacities could be expressed as relations between absolute heats of substances at a given temperature. Crawford first set to “compare the absolute heat of fixed air and phlogisticated air, with that of atmospherical air.”448 He found that the heat ratio of fixed

447 Crawford (1779), p. 95. 448 Crawford (1779), p. 34.

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air to water was “1 to 3.6” and that of common air to water was “18.6 to 1” and thus he calculated that the heat ratio of common air to fixed air was “very nearly as 67 to 1.” Since the absolute heat ratio of dephlogisticated air to water was found to be “as 87 to 1,”

Crawford found the absolute heat ratio of dephlogisticated air to common air to be “as 87 to 18.6 or nearly as 4.6 to 1.” According to these results, when arranged by a descending scale of heat capacities, the order of the airs would be: dephlogisticated air, common air and fixed air, which corresponded to the order of the respective airs in Crawford’s pneumatic-phlogistic sequence. This suggested that dephlogisticated air, upon undergoing phlogistication and being subsequently converted into fixed air, lost a considerable quantity of its (natural) heat, which in combustion and respiration was released as sensible heat. In the context of the airs’ purity, this also corroborated Priestley’s discovery that the power of dephlogisticated air, “in supporting animal life, is 5 times as great as that of atmospherical air.”449 Crawford conducted analogous experiments on metals and their calces and thus determined that “the absolute heat of the calx of tin is to that of tin, as 14.7 to 10.4.” Similarly, the absolute heat ratio of the calx of iron to that of iron was found to be “as 8 to 3.1” and that of the clax of lead to lead “as 19.9 to 14.7.”450 “We may therefore conclude,” he noted,

that bodies, when joined to phlogiston, contain less absolute heat than when separated from it; and consequently, that, in the former case their capacities for containing heat are diminished, and in the latter, increased. It follows, that if phlogiston be added to a body, a quantity of the absolute heat of that body will be extricated; and if the phlogiston be separated again, an equal quantity of heat will be absorbed… heat, therefore, and phlogiston appear to be two opposite principles in nature. By the action of heat upon bodies, the

449 Crawford (1779), pp. 50-53. 450 Crawford (1779), pp. 61, 63-64.

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force of their attraction to phlogiston is diminished; and by the action of phlogiston, a part of the absolute heat, which exists in all bodies as an elementary principle, is expelled.451

Black advanced the theory of latent heat and Irvine proposed to further distinguish it from specific heat, which under Crawford became systematically quantified as well as conceptualized (figure 1). Crawford’s endeavor consisted in a synthesis of two key research traditions: Priestley’s observations of the 1770s on air(s) and his corresponding perceptions on their phlogistic permutations on the one hand, and Black’s and Irvine’s research into the chemico-physical theory of heat on the other. Donovan pointed out that although pneumatic chemistry “seems to be such a natural extension of [Black’s] investigation of fixed air that we are surprised to find him abandoning this subject for the study of heat”; indeed, Black did not perceive the study of airs as attractive for a philosophical chemist.452 Bringing together the discoveries of Black, Irvine and Priestley,

Crawford’s experimental research consisted of what was probably the “earliest [effort] made to determine the specific heats of gases.”453 Crawford’s pioneering fusion of research traditions and experimental practices paved the way for Kirwan’s theoretical breakthrough, to which we shall turn shortly.

Crawford’s establishment of the mutual opposition between heat and phlogiston, on experimental and quantitative grounds, was highly consequential; it was to this specific conclusion that Bergman referred to as the opinion according to which “elementary fire… is not only different from phlogiston, but so opposite that one every where expels the other,

451 Crawford (1779), pp. 67-68. 452 Donovan (1975), pp. 218-219. 453 Mendelsohn (1964), p. 127.

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at least in part. Air during phlogistication gives out much specific fire, which, when free, heats, calcines, causes ignition, etc.” This observation enabled Crawford to bring his initial line of research to a closure. Drawing upon Priestley’s observations that “in respiration, phlogiston is separated from the blood and combined with the air” and that

“arterial blood has a great attraction to phlogiston,” Crawford clarified the relation between respiration, the circulation of the blood and the propagation of heat.454 During its circulation, arterial blood took up phlogiston and subsequently imparted heat to the body parts. Venous blood, on the other hand, returned to the lungs highly impregnated with phlogiston (and thus containing little heat), and was there dephlogisticated while absorbing heat from the air. “Thus it appears,” Crawford claimed,

that, in respiration, the blood is continually discharging phlogiston and absorbing heat; and that in the course of the circulation, it is continually imbibing phlogiston and emitting heat… We may, therefore, safely conclude, that the absolute heat which is separated from the air in respiration, and absorbed by the blood, is the true cause of animal heat.455

By the same token, the parts of the body that give away phlogiston to the blood would gain

“absolute heat.” That the heat obtained during respiration—“animal heat”—originates from the air, and not from the body, is a remarkable observation, which led Crawford to a complete explanation of combustion:

inflammable bodies abound with phlogiston, and contain little absolute heat; atmospherical air, on the contrary abounds with absolute heat, and contains little phlogiston. In the process of inflammation, the phlogiston is separated from the inflammable body, and combined with the air; the air is combined into fixed and phlogisticated air, and at the same time gives off a

454 Crawford (1779), pp. 72-73; Priestley (1775-77), III. 455 Crawford (1779), pp. 74-75.

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very great proportion of its absolute heat, which, when extricated suddenly, bursts forth into flame, and produces an intense degree of sensible heat.456

Crawford retained traditional phlogistic precepts, according to which “inflammable bodies abound with phlogiston.” Scheele, it will be recalled, who was greatly interested in the relation between heat and phlogiston, assumed heat to be a permutation of fire air (or dephlogisticated air), superabundant with phlogiston. As the end result of a phlogistication of air, heat was perceived as a compound of air and phlogiston, both entities being material and ponderable. Thus for Scheele combustion consisted in the union of that “third part of common air” (fire air) and of “an inflammable substance” (phlogiston). For Crawford, phlogiston combined with the air, transmuting it into fixed air, while disposing with a pre- existent amount of heat, which became released and “bursts forth into flame.” Crawford’s introduction of fixed air into Priestley’s original sequence can now be reassessed in light of his formulation of the inverse relation between phlogistic and heat contents. By drawing upon comparative heat contents Crawford concluded that, “the absolute heat of atmospherical air is greater than that of fixed air or phlogisticated air.”457 On the basis of the implied inverse degree of phlogistication, atmospherical air was judged to contain more phlogiston than both fixed and phlogisticated airs and hence preceded both these airs in

Crawford’s pneumatic sequence. Hence for Scheele air became heat while for Crawford air became fixed air and heat. More significant, from a pneumatic perspective, phlogistication during combustion was viewed by Scheele as a process of aerial composition whereas Crawford perceived it as a process of aerial decomposition.

456 Crawford (1779), pp. 76-77. 457 Crawford (1779), p. 42.

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Figure 1. Crawford’s conceptual representation of the relationship between “heat capacity” and “absolute heat” in two bodies or “quantitative matter” (Crawford, 1779, pp. 89, 100- 101).

KIRWAN ENTERS THE PHLOGISTIC ARENA: INNOVATIONS AND RENOVATIONS

In Kirwan’s commentary on Scheele’s treatise, Priestley is mentioned thirty-eight times, which squares well with the fact that Kirwan regarded Priestley as the leading authority in contemporary pneumatic research. Crawford and Fontana are referred to fourteen times each. Felice Fontana (1730-1805), Italian physiologist and naturalist, exhibited a keen interest in pneumatic chemistry and its particular link to respiration. Like

Crawford and Kirwan, he accepted Priestley’s basic phlogistic transmutational tenet and his first contribution on the subject appeared in 1776 as Recherches physiques sur la nature de l'air nitreux et de l'air déphlogistiqué. During the late 1770s and early 1780s

Fontana launched vigorous attacks on Scheele’s phlogistic doctrine in a series of articles

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published in the journal Observation sur la physique.458 This theoretical inclination on the

Italian’s part accounts for Kirwan’s reliance on some of Fontana’s observations in his own critique of Scheele. A close examination of Fontana’s contributions to the emerging chemistry of airs transcends the scope of this chapter but merits an independent study.

Kirwan’s 1780 critique of Scheele’s work can be read on several levels. This appended document captures an intertwined mélange of experimental and theoretical aspects, expressing Kirwan’s SER and chemical motivations. Officially designed as a critique of Scheele’s experiments and phlogistic interpretations, it reveals Kirwan’s sources of reference and inspiration. At the same time, however, this document was employed by Kirwan as a foil to advance his own original notions, revolving around a fusion of Crawford’s then-innovative research with Priestley’s observations. In his “notes”

Kirwan commented upon sixty-two out of the ninety-seven entries included in Scheele’s treatise. In entry #72, entitled simply Phlogiston, Scheele drew several specific conclusions. First, he claimed, “Phlogiston is a true element and a simple principle.”

Secondly, it can enter into bodies, which “by the effect of the particles insinuating themselves in the interstices of bodies, to go over into fusion, or even into elastic vapours.”

Thirdly, it “enters into so close and subtle an union with empyreal Air that it even penetrates through the most subtle pores of all bodies,” from which “union arises both the matter of light, and likewise the matter of heat.” Lastly, in line with traditional precepts,

458 Belloni (1970-80).

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Scheele stressed that “phlogiston can by no means be obtained by its own” since it is always bound with other substances.459

Figure 2. Kirwan’s table of specific heats (reproduced in McKie and Heathcote, 1958).

In response, Kirwan introduced the following proposal, which would comprise the basis of his mature doctrine of phlogiston, as advanced in his 1787-89 Essay:

The principal characters of phlogiston seem to me to be [A], its strong attraction to elementary Air, mineral acids, and metallic earths, together with the properties that result to these substances from their union with it. [B], Its repulsion with regard to elementary Fire, and Water.

459 Scheele (1780), pp. 104-105.

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[C], The heat which always arises from its union with Air, or with any other substance whose capacity to contain Fire is greater than that of the body from which the phlogiston was transferred. [D], Its properties in its purest state; which I take to be that of inflammable air from metals.460

Points B and C are unmistakably reminiscent of Crawford’s observations. Kirwan, nevertheless, adopted these notions only after having validated them on a thorough experimental basis. Prior to his 1780 phlogistic debut, Kirwan exhibited a vivid interest in theories of heat and collaborated on the subject with Jean Hyacinthe de Magellan (1723-

1790). Employing the mixture method, Kirwan produced what seems to have been the first table of ‘specific heats’ (chaleur spécifique)—a newly-introduced term—which was reproduced by Magellan in his Sur la nouvelle théorie du feu élémentaire, et de la chaleur des corps reprinted in 1781 in Observations sur la physique.461

Like Crawford, Kirwan employed the mixture method and used water as a standard, valued at 1. The results he obtained corroborated Crawford’s 1779 findings.

With respect to airs: common air 18.67; fixed air 0.27; dephlogisticated air 87; regarding metals and their calces: iron and lead 0.125 and 0.05, respectively, and 0.32 and 0.068, in their calces, respectively. Subsequently, Kirwan was experimentally convinced of

460 Scheele (1780), pp. 232-233; It should be noted that the alphabetical listing (A, B, C, D) does not occur in the text but was introduced by the author for the sake of convenience in reference to Kirwan’s four different statements. The original text reads: “1st, 2dly, 3dly and 4thly,” respectively. 461 See Scott (1981), who speculated on the origin of this term and is inclined to attribute it to Kirwan. Scott quotes from Kirwan’s 1787 An estimate of the temperatures of different latitudes: “All bodies require a certain quantity of elementary fire or light to heat them to a certain degree, but the quantity requisite to produce this degree varies, according to the nature and species of these bodies, and hence the proportion suited to each is called their specific fire.” (p. 146). For a singular study dealing with the collaboration between Kirwan, Magellan, Crawford and others—as the founder-members of the “Coffee House Philosophical Society”—see Levere & Turner (2002).

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Crawford’s proposal according to which there existed an inverse relationship between phlogiston and heat and, furthermore, that the actual quantity of phlogiston in a substance determined its heat capacity. Accordingly, fixed air, the perceived product of the phlogistication of dephlogisticated air, contained little heat but much phlogiston while dephlogisticated air contained much heat yet little phlogiston. This meant that the heat, apparent in combustion and other processes, proceeded from the air, which was stripped of its heat while imbibing phlogiston.

The major source of contention between Kirwan and Scheele arose from their diverging conceptions of the nature of heat and its role in pneumatic processes such as combustion and respiration. In entry #76 Scheele ventured to present a “theory of the generation of Fire, and the phenomena it causes,” the main features of which have been discussed above.462 Kirwan’s astute commentary on this subject exposes the essence of the controversy:

a very slight alteration will make many of his [Scheele’s] explanations consistent with truth; for he asserts, that phlogiston and pure Air compose heat; and in truth heat results from their union; because, as Dr. Crawford has proved, elementary Air contains more Fire than any known substance, but by uniting with phlogiston, its capacity for containing it is diminished, and consequently this Fire is let out, becomes redundant, and causes sensible heat.463

Kirwan agreed with Scheele that when dephlogisticated (or elementary) air united with phlogiston, heat was produced. But while Scheele believed the two entities to be the constituents of heat, which he viewed as a ponderable entity, Kirwan suggested, relying

462 Scheele (1780), p. 111. 463 Scheele (1780), pp. 236-237.

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upon Crawford, that the phlogiston merely disengaged heat from the air, in which it preexisted. Once released from the air, “Fire is let out, becomes redundant, and causes sensible heat.” The disagreement reflects deep metaphysical disparities. However, from a strictly formal point of view, the opponents agreed not only upon the phenomena but also upon the nature of the reactants involved. Their radically different interpretations of the mechanism of the reaction arose from their different perceptions of the constitutive attributes of the entities involved: air, phlogiston and heat.

Given this context, we can now reassess Fourcroy’s conciliatory tone in mentioning

Lavoisier alongside Stahl and Kirwan. The latter has been associated with “the doctrine most generally received in Britain,” according to which gaseous phlogiston was identical to inflammable air. The conceptual similarity found between the two, allegedly rival, interpretations is striking. According to Fourcroy’s message, Lavoisier stressed the immateriality of referential issues (such as the lack of a fixed referent to phlogiston) as reflected in chemical nomenclature. For whether it was the “phlogiston of Stahl, or the fixed light of Macquer,” it was some kind of “matter of fire or of heat,” which was disengaged from “pure air” during combustion. Subsequently, the central issue was that the sensible phenomena related to combustion—heat, light, flame—originated from the air and not from the inflammable body. Kirwan, relying on Crawford’s findings, reasoned along surprisingly similar lines: while phlogiston was given off by the body, heat originated from the decomposition of air. Crawford, as seen, explained “the process of inflammation” as a combination of phlogiston from the body with air, which in turn, was decomposed. One part of this air was “combined [transmuted] into fixed and phlogisticated air” while the other part gave off “a very great proportion of its absolute

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heat,” which appeared as flame and “an intense degree of sensible heat.” In a similar vein,

Kirwan suggested that during combustion “the Fire then produced to view, proceeds from the Air, and not from the combustible substance; which, on the contrary, receives a great part of it, at the same time that it communicates phlogiston.”464

The significance of points B and C notwithstanding, the most distinctive feature of

Kirwan’s inaugural formulation arises from point D, identifying phlogiston “in its purest state” with “inflammable air” (this view is referred to by Priestley in his letter to

Wedgwood; see p. 188). Scheele awarded phlogiston a material-elemental status but pointed out the impossibility of isolating it. In line with his own SER, Priestley’s theoretical perceptions were more ambiguous: since the presence or absence of phlogiston occasioned a “remarkable difference in bodies” and it could be “transferred from one substance to another, according to certain known laws,” he believed it to be “a real something”; in fact, it probably was “a substance itself, though incapable of being exhibited alone.”465 Kirwan’s identification of phlogiston with a recognizable and distinct type of air was unique in that it implied that phlogiston could be “exhibited alone,” a view never espoused before.

Notably, in his point D, Kirwan referred specifically to phlogiston as “inflammable air from metals,” in accordance with the fact that inflammable air was a common product of metallic dissolutions. Yet Kirwan’s 1780 statement should also be interpreted in the context of its role as a response and reaction to Scheele’s observations. As seen, inflammable air had a special significance in Scheele’s pneumatic outlook: it was

464 Scheele (1780), p. 224. 465 Priestley (1775-77), I, p. 282.

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considered as the most phlogisticated pneumatic entity in his sequence and was consequently situated after light. Scheele explained that heat—a compound of air and phlogiston—“with a small addition of phlogiston it produces light; and with still more, the well-known inflammable air.” The 96th and penultimate entry in his treatise was dedicated to Inflammable Air, in which Scheele elaborated upon the production of this air during certain metallic dissolutions. He first postulated that “all metals” consisted “of an earth sui generis, united with a certain quantity of phlogiston, and a certain quantity of heat” and added that “the more phlogiston a metal contains, the more heat is likewise found with it.”

He then explained:

The acids unite with their earths, and the discharged phlogiston with the same acids: if the latter have no attraction to the phlogiston it is attracted by the air; if this is wanting, it unites with heat, which in the same moment is discharged from the metals by the acids… and thus the inflammable air is compounded.466

To which Kirwan responded that, “the very reverse of the maxim here laid down by Mr.

Scheele, namely, that metals contain so much more heat, as they contain more phlogiston, has since been demonstrably proved by Dr. Crawford.” Once more, Kirwan’s statement bears witness to his far-reaching reliance upon Crawford’s research, which is best evidenced in Kirwan’s own formulation of point B. Being opposed to Scheele’s explanation concerning the constitution of metals and the relation between heat and phlogiston, Kirwan rejected Scheele’s interpretation regarding the source of inflammable air, which was according to Kirwan, phlogiston in a gaseous state, a concept we shall turn to next. As evident as Crawford’s influence is in this context, Kirwan relied, too, on the

466 Scheele (1780), pp. 178-179.

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experiments of “Dr. Priestley [who] has extracted inflammable Air from metals in closed vessels full of quicksilver,” which, he explained, “directly overturns this part of Mr.

Scheele’s system,” referring to the latter’s conception of the constitution and origin of inflammable air.467

Between 1780 and 1787, the year that saw the publication of the first edition of the

Essay, Kirwan developed his phlogiston-as-inflammable-air theory. As seen, in 1780, his phlogistic perception was found in an embryonic state. Although he proposed, for the first time, the identification of phlogiston with inflammable air, Kirwan did not provide further explanations. Nor was this bold move unqualified, for it was formulated with a specific context in mind—phlogiston, “in its purest state… [as] inflammable air from metals.”468

Two years later Kirwan presented a substantially expanded version of his metaphysical outlook concerning the “nature” of phlogiston. One of the most consequential aspects of

Kirwan’s innovative view was the fact that phlogiston was claimed to exist freely in the form of an air. The fact that phlogiston could assume a gaseous state required an explanation:

It is allowed on all hands, that fixed air, or the Aerial Acid, as it is more properly called, is capable of existing in two states; the one fixed, concrete, and unelastic, as when it is actually combined with calcareous earth, alkalies, or magnesia; the other, fluid, elastic, and aeriform, as when it is actually disengaged from all combination. In its concrete and unelastic state it can never be produced single and disengaged from other substances; for the moment it is separated from them, it assumes its aerial and elastic form. The same thing may be said of phlogiston: it can never be produced

467 Scheele (1780), pp. 248-249. 468 Although he does not argue in favour of a clear connection, Mauskopf mentions in this context Cavendish’s 1766 identification between phlogiston and inflammable air. Mauskopf (2002), pp. 190-193. Cavendish’s statement is an isolated instance, not linked to any broader considerations and seems to be a mere fleeting observation upon an experimental phenomenon. Nor does Kirwan make any mention of Cavendish, which evinces the strong circumstantial nature of this association.

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in a concrete state, single and uncombined with other substances; for the instant it is disengaged from them, it appears in a fluid and elastic form, and is the commonly called inflammable air.469

At the heart of this explanation lies the analogy between the different known states of existence of “fixed air” and phlogiston. This analogy not only demonstrated phlogiston’s pneumatic existence but also accounted for the way by which it could react with other solid substances. “The separation of phlogiston from a metallic earth in the form of inflammable air,” for instance, was attributed to the fact that “there is always a double decomposition”: “the dissolving acid yielding its fire to the phlogiston, which then assumes as aerial form, while the phlogiston yields the metallic earth to the acid.”470

Accordingly, phlogiston could enter into “combination” with other materials by assuming a “fixed, concrete, and unelastic” state. Yet even more revealing is the theoretical basis Kirwan provided for this analogical reasoning: “these different states of the same substance arise,” he asserted, “according to the immortal discoveries of Dr.

Black, from the different portions of elementary fire contained in such substance, and absorbed by it, whilst its sensible heat remains the same, and called specific fire.”471

Kirwan’s “specific fire” is analogous to Crawford’s heat capacity, which, as seen, indeed originated with Black and especially with Irvine. Crawford’s discoveries and formulation of the relation between phlogiston and heat enabled Kirwan not only to reject Scheele’s interpretation of the production of inflammable air but also paved the way for his revolutionary suggestion that phlogiston could exist “in a fluid and elastic form” as

469 Kirwan (1782), p. 195. 470 Kirwan (1782), pp. 195-196. 471 Kirwan (1782), p. 196.

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inflammable air. Black and Irvine’s research into the chemico-physical qualities of heat, imported by Crawford into a pneumatic-phlogistic framework, was adopted by Kirwan and developed into a novel and challenging doctrine of phlogiston.

The synthetical origin of Kirwan’s notion of phlogiston-as-inflammable-air, however, embodies yet another perspective. At the hands of both Priestley and Scheele, phlogiston was a distinctly chemical entity: in line with their SER, it was deemed an agent that could not be isolated but that was recognizable and manipulable within a chemically operative framework (not unlike the one advanced by Duclos). It was detectable through a particular and self-consistent network of chemical signs and manifestations such as peculiar reactions, processes and their typical end products, affinities, or other sensible phenomena. From such a chemical-operative epistemological perspective, within the context of the present discussion, phlogiston was above all else the agent that brought about the transmutation of pneumatic entities. As such, the different, specific and recognizable kinds of pneumatic substances attest to phlogiston’s existence; their coming into being signals dephlogistication or phlogistication, and, by derivation, phlogiston. The regularities that characterize the aforementioned phlogistic-pneumatic sequences are interpreted chemically as signs of the presence of phlogiston. Discussing the nature of phlogiston, both Priestley and Scheele exhibited a similar SER. Although they differed in their phlogistic-compositional outlooks, neither chemist was bothered by the impossibility of isolating phlogiston. Scheele, for instance, stressed phlogiston’s strong affinity to air, or the way it systematically forms such a “close and subtle an union with empyreal Air.” This chemical affinity, or established particular law of attraction, was the chemical cause of compounds such as “both the matter of light, and likewise the matter of heat.” In this case,

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it was this very affinity that signaled the presence of phlogiston (see section in chapter 4 on Affinity as a Force and the Force of Affinity). Granted this kind of chemically oriented epistemology, founded upon sensible regularities as observed in the operational realm, the claim that “phlogiston can by no means be obtained by its own,” made no difference.472

Priestley offered a more general explanation in arguing that phlogiston is “a real something” since it occasioned a “remarkable difference in bodies” and it could be

“transferred from one substance to another, according to certain known laws.” He, too, remained unworried by the fact that phlogiston was “incapable of being exhibited alone.”

It was here that Kirwan’s SER differed substantially from both Priestley’s and Scheele’s.

As we have seen, in formulating his own phlogistic doctrine, Kirwan reacted, although differently, to both Priestley’s and Scheele’s findings. What sets Kirwan apart is that, unlike them, he expressed dissatisfaction with the fact that “for want of attention to these different states [concrete and elastic], the very existence of phlogiston as a distinct principle has been frequently called in question.”473 In light of this particular concern

Kirwan sought a material physical existence for phlogiston. It is not the mere identification of phlogiston with a known gas that is consequential here but rather the nature of the mechanism that underlies this identification. Scheele and Priestley differed, metaphysically, in their interpretation of the relation between phlogiston and other pneumatic entities: air(s), heat and light. Yet as far as phlogiston’s existence was concerned, they shared a similar view—as part of the same chemical operative epistemology—according to which the physical existence of phlogiston was irrelevant as

472 Scheele (1780), pp. 104-05. 473 Kirwan (1782), pp. 195-96.

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long as phlogiston was possessed of a peculiar chemical mode of existence within which it could be identified and manipulated.

By advancing his doctrine of phlogiston as inflammable air, Kirwan sought to absolve phlogiston from the growing doubts concerning its physical existence. Such metaphysical hesitations go all the way back to Macquer.474 But the work of the

Lavoisians—and their emphasis on the conservation of weight and matter—increased these doubts dramatically by furnishing them with new experimental and theoretical foundations and by replacing the chemical perceptions with a physically-oriented epistemology supplemented by a new all-encompassing nomenclature. Kirwan employed Crawford’s research on heat, which in turn drew on Black and Irvine, to endow phlogiston with a physical existence by elaborating upon the nature of the gaseous state. Yet at the same time, Kirwan was as much committed to the older pneumatic metaphysics, which revolved around phlogiston’s transmutational agency in relation to the constitution of air(s). In this respect, Kirwan’s SER represented an integrative stand. Kirwan’s reconciliation between the physical and the chemical turned out to be short-lived. This apparently advantageous move turned into the bane of Kirwan’s phlogistic chemistry. Attempting to ‘save’ phlogiston, Kirwan reacted by attempting to meet some of the requirements created and introduced by the French “crisis-provok[ers],” a move that compromised phlogistic chemistry irreparably. By way of analogy, Kirwan, whose essentially integrative SER was forged by both chemical and physical influences, made a concession; the possibility of this compromise would not been even recognized by the likes of Duclos, Priestley or Scheele.

474 Macquer (1771), II, p. 516.

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Having addressed the subject of “the very existence of phlogiston as a distinct principle” Kirwan turned his attention to another aspect that increasingly burdened the phlogistic cause. The Lavoisians’ work on the conservation of weight in pneumatic reactions made it progressively difficult to explain, from a phlogistic standpoint, the augmentation of metallic weight during calcination, for instance. Metals, according to the phlogistic view, were said to be composed of phlogiston and a specific earth and since during calcination the metal loses its phlogiston, the resulting calx should weigh less than the original metal, which went against weight measurements. Kirwan held to this traditional phlogistic view but offered a novel explanation of the increase in weight. One of Crawford’s most significant pneumatic contributions, it will be recalled, was his assertion that “there is no instance of a phlogistic process in nature, which is not accompanied with the production of fixed air.” Further, during pneumatic reactions, dephlogisticated air combined with phlogiston to produce fixed air (and phlogisticated air, which already existed in common air). We have seen how Kirwan adopted Crawford’s general explanation of combustion, according to which “the Fire then produced to view, proceeds from the Air, and not from the combustible substance.” But he also subscribed to

Crawford’s idea that “combustion consists in the rapid separation of phlogiston from combustibles by Air; that phlogiston so separated, unites to the Air; that aerial acid, or fixed Air is then deposited.”475 Crawford believed that common (atmospherical) air turned into fixed and phlogisticated airs upon phlogistication. Kirwan differed in maintaining that, “fixed air consists of elementary Air and phlogiston” whereas “phlogisticated air…

475 Scheele (1780), pp. 222-223.

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[consisted] of fixed Air, supersaturated with phlogiston.” He stressed, moreover, that, “in phlogistic processes, fixed Air is generally generated, and not phlogisticated air; so that the phlogisticated Air that remains after such processes pre-existed, and was not formed by those processes, but that the production of fixed Air is their genuine effect.”476

Consequently, according to Kirwan’s pneumatic transmutational sequence, dephlogisticated air was followed by fixed air, which was followed in turn by phlogisticated air. The elimination of common air as a distinct pneumatic step represented yet another revision of the basic pneumatic sequence advanced by Priestley in 1775 and modified by Crawford in 1779. (Table 1: D).

The notion that fixed air was generated in phlogistic processes—as a combination of dephlogisticated air and phlogiston—enabled Kirwan to explain the weight increase in combustion and calcination:

As to the calcination of metals, Dr. Priestley has observed, that by this operation respirable air (and only respirable air) is diminished between one- fourth and one-fifth, both in its weight and bulk; but Mr. Lavoisier has demonstrated, that nothing is lost or escapes through the vessels (as Mr. Scheele would have it)… That part, therefore, which the air loses is taken up by the metallic calx, which accordingly is found to gain the very weight which the air loses. Now the air contained in the calx is fixed air.477

Kirwan concluded that in various calcination processes, fixed air, which is invariably produced, is reabsorbed by the metals that subsequently gain weight. In line with his pneumatic sequence, he explained: “In all these cases the fixed air could surely come from

476 Ibid., p. 221. Two years later he repeated: “Phlogisticated air consists of fixed air supersaturated with phlogiston.” Kirwan (1782), p. 222. 477 Kirwan (1782), p. 214.

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nothing else but the incumbent respirable air and the phlogiston of the metal.”478 For

Lavoisier metallic calcination occurred when air was decomposed into caloric (matter of heat) and oxygen, which united to the metal. Kirwan was true to his belief that processes involving the matter of heat entailed a double decomposition. This perception rested upon the principle concerning the inverse relationship between phlogiston and heat and

Kirwan’s consequent formulation of his aerial pneumatic sequence. He noted that, “we see how fixed air is generated in most other phlogistic processes, performed in common air.

The phlogiston is attracted by the dephlogisticated part of common air, unites to it, expels part of its fire, and so forms fixed air.”479 Harking back to notions regarding the “different states of the same substance” as advanced “by the immortal discoveries of Dr. Black”—in allusion to the physical implications of the theory of latent heat—Kirwan denied the chemical status of Lavoisier’s pneumatic interpretations:

While inflammable air is (as Dr. Priestley elegantly expresses it) in its nascent state, before it acquires its whole quantity of specific fire, respirable air easily unites to it, and is diminished in proportion to its purity… [but if the mixture be sufficiently heated]… both [airs] uniting give out their fire, or in other words inflame, when in proper proportion to each other, without any decomposition of either, unless the loss of a great part of their specific fire be called a decomposition, which loss is not usually called a decomposition; for water is never said to be decomposed when it becomes ice, nor metals when they become solid on cooling.480

In conclusion, “respirable air” does not undergo “decomposition” during combustion, since

“the loss of a great part” of its heat—or escape of caloric, in Lavoisier’s terms—does not comprise a chemical decomposition; it is but a physical change of state like the freezing of

478 Kirwan (1782), 214-215. 479 Ibid., p. 220. 480 Ibid., p. 201.

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“water” or the solidification of “metals.” Alluding to Crawford’s discoveries and by inference to Kirwan’s doctrine of fixed air, as arising from his pneumatic sequence,

Bergman concluded that “the doctrine concerning the origin of animal heat, is reducible to the fundamental question, concerning the change of vital air into aerial acid [fixed air], and of this into corrupted [phlogisticated] air; an opinion to which everyday seems to receive confirmation.”481

In 1784 Cavendish published his crucial findings, establishing that, “on the whole, though it is not improbable that fixed air may be generated in some chymical processes, yet it seems certain that it is not the general effect of phlogisticating air.” Furthermore, he suggested, “when inflammable and common air are exploded… all the inflammable air, and near one-fifth of the common air, lose their elasticity, and are condensed into dew… it appears that this dew is plain water.”482 Bergman’s translator, Thomas Beddoes, in an appended note, remarked that “before the publication of Mr Cavendish’s paper on air… Mr

Kirwan seems to have almost succeeded in persuading chemists, that fixed air is generated in phlogistic processes, by the union of vital air with phlogiston.” Cavendish’s experiments, however, Beddoes suggested, cast an insurmountable doubt upon Kirwan’s arguments since “the complete proof, from unequivocal, analytical, and synthetical experiments, was wanting, and many of the most important cases of phlogistication gave no sort of countenance to the supposition.”483

481 Bergman (1785), pp. 277-278. 482 Cavendish (1784), pp. 123, 129. 483 Bergman (1785), pp. 352-353.

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Cavendish’s discovery concerning the constitution of water evolved, over the next few years, into one of the cornerstones of the chemical revolution. Following a short but fierce debate between Kirwan and Cavendish, the notion, established by the latter, that the result of the phlogistication of dephlogisticated air was water, and not fixed air, provided the Lavoisians with vital evidence in favour of their system. Similarly, in Kirwan’s words, published three years later, it was “the important discovery of the composition of water made by Mr. Cavendish… [that] furnished him [Mr. Lavoisier] with a new and unexpected source from which he could derive the inflammable air, extricated in various operations on inflammable and metallic bodies.” Endowed with a “new and unexpected source” for phlogiston, the French revolutionaries proceeded to “reverse the ancient hypothesis,” render phlogiston “superfluous” and ultimately eliminate it.484

In 1787, well aware of the multiple views that “favour the new opinion…[i.e.] the

Antiphlogistic hypothesis,” Kirwan still recommended “the old system” as the “more uniform of the two” while warning against the new system’s “false shew of simplicity,” a perception discussed extensively in chapter 4.485 Throughout the course of the 1787-89 controversy—encompassed by the Essay—Kirwan employed the doctrines of ‘phlogiston as inflammable air’ and ‘fixed air’ in offering phlogistic interpretations of all the chemical phenomena under debate. As we have seen, the rise and evolution of these

“modifications” followed a complex and elusive path, the reconstruction of which illustrates how metaphysical commitments and epistemological practices, associated with distinct research goals, commingled to produce phlogistic pneumatic knowledge.

484 Kirwan (1789), pp. 4-5. 485 Kirwan (1789), pp. 7-8.

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CONCLUSION

In 1777, around the time Kirwan had initiated his own chemical research on affinities and heat capacities, Scheele announced, as part of an ambitious attempt to formulate a “chemical doctrine of fire,” a model that integrated the two most salient research themes in phlogistic chemistry: the constitution of air(s) and of heat (as well as light). Although developed independently and despite important differences, Scheele’s approach shared several core metaphysical assumptions with Priestley’s phlogistic outlook, which Priestley had formulated in 1775. Both chemists envisioned phlogistication and dephlogistication as pneumatic transmutational processes, which followed distinct sequential patterns, the “regular gradation[s]” of which corresponded to various identifiable pneumatic entities. This metaphysical conception of pneumatic entities— air(s), heat, light—as phlogistic permutations of one another entailed a chemical operative epistemology, the modus operandi of which was contingent upon regularities found in degrees of phlogistication.

Reacting against particular aspects of Scheele’s phlogistic pneumatic sequence,

Kirwan advanced, in 1780, a pneumatic outlook that drew upon and combined the basic tenets of Priestley’s phlogistic sequence with Crawford’s novel articulation of the inverse relationship between phlogiston and heat, on the one hand, and his emphasis on the production of fixed air in pneumatic reactions on the other. In combining these two research avenues, with their particular orientations and peculiar sets of data, Kirwan departed from the distinctly chemically-informed pneumatic research tradition (as practiced, for instance, by both Priestley and Scheele). Importing notions concerning the physico-chemical nature of heat, derived from the Scottish tradition going back to Irvine

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and Black, Kirwan devised an integrative stand, which carved out the theoretical space required for the assimilation of a distinct air with the aeriform state of phlogiston. This bold theoretical move, coupled with the new status accorded to fixed air, enabled Kirwan to account for phlogiston’s increasingly pressing difficulties. At the same time, as shown above, Kirwan brought about a major shift in the topography of the conceptual battleground of the Chemical Revolution. We now turn to examine this shift against a broader contextual background, depicting in greater detail the rival views and SERs at the core of this Revolution.

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CHAPTER 4

CHEMICAL UNIFORMITY AND THE RISE OF A “FALSE SHEW OF SIMPLICITY”

INTRODUCTION

Though the late experiments demonstrate that phlogiston does not give weight or heaviness to metals, that phlogiston does not disengage itself from the sulphur during formation of the sulphuric acid; yet we still allow the absolute existence of a phlogiston. It is still the matter of fire, of flame, of light, and of heat which is liberated in combustion; the only difference is, that we do not agree with Stahl, that this principle disengages from the body in combustion… [we believe] that it is liberated from the vital air on the precipitation of the oxygen. Yet it is still phlogiston with its most distinguishing attributes. In short, it is still the matter of heat; whether we call it phlogiston, caloric, or in plain English, fire.486

The author of this paragraph, James St. John, was anything but a belated defender of phlogiston theory.487 In this passage he is prefacing his own English translation of the

Lavoisians’ seminal Method of Chymical Nomenclature, the work that is customarily taken to have all but concluded the takeover by the new French chemistry. Writing only one year before the publication of Lavoisier’s Elements of Chemistry, St. John granted that

“experiments demonstrate” that combustion and calcination processes cannot be accounted for in traditional phlogistic terms. Phlogiston is neither a component of “metals” nor of

“sulphur.” Yet he insisted that we have to “still allow the absolute existence of a phlogiston.”

486 Berthollet & Fourcroy & de Morveau (1788), x-xi. 487 On St. John and the translation of the Method see Crosland (1978), pp. 193-194; St. John, is said to have been “convinced of the superiority of the oxygen theory and the new nomenclature.”

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Why? What did St. John find amiss in the chemistry he was presenting to the

English reader that required clinging to the “absolute existence” of an entity whose elimination was one of its main aims and achievements? Perhaps the most surprising, and hence most telling aspect of St. John’s remark was this insistence on the “absolute existence” of phlogiston over and above the hypothetical properties that gave this entity its theoretical import and sustained it for two-thirds of century. Found in the preface to the

Method, this is all the more striking, since one of the core motivations of this work was to assure that each chemical term connoted the precise composition, hence properties, of the substance it denoted.488

The claim that “it is still phlogiston” was not peculiar to St. John. Fourcroy, as we have seen, one of the co-authors of the Method and Lavoisier’s close collaborator expressed a similar sentiment in asserting that “the matter of fire or of heat… can be nothing else than the phlogiston of Stahl, or the fixed light of Macquer; and that all chemists are of course agreed that it exists.”489 Like St. John, Fourcroy assumed that phlogiston had already been stripped of its traditional theoretical functions and properties, but insisted on its existence, which was allegedly agreed upon by all chemists. Even staunch supporters of the “anti-phlogistic theory,” it appears, found it hard to depart from this beleaguered entity.490 Even if the nature and existence of phlogiston was problematic,

488 Laying claims concerning the success of the new “method” Lavoisier boasted that “we have so well succeeded that by a single word, it is instantly evident what is the combustible substance entering into any composition; if that combustible substance is combined with the acidifying principle, and in what proportion; in what state the acid is, and to what basis united; if there is a perfect or exact saturation; and if it is the acid or if it is the basis which is in excess.” Berthollet & Fourcroy & de Morveau (1788), p. 16. 489 Fourcroy (1788), I, p. 142; see p. 199 (fn. 427). 490 Kirwan (1789), p. 7.

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it was not more so than that of the new theoretical entities proposed in its stead to account, in particular, for what Fourcroy referred to as “the matter of fire or of heat,” or, in St.

John’s words, “the matter of fire, of flame, of light, and of heat.” Over a decade later, in his 1792 First Principles of Chemistry, William Nicholson skeptically noted that, “the existence of heat, light, and phlogiston, as chemical principles of bodies, is not yet incontrovertibly established.”491

Phlogiston, of course, survived well beyond Lavoisier’s “Experimentum Crucis,” as even Priestley referred to the calcination of metals.492 Nor was it laid to rest with

Lavoisier’s ensuing publications, beginning with the 1775 “Easter Memoir” and culminating with the Elements of Chemistry of 1789.493 As we have seen, in his 1780

Treatise on Air and Fire, Scheele reasoned exclusively within a phlogistic framework and dedicated an entry to phlogiston.494 Bergman’s ‘Table of Affinities’, published in his 1785

Treatise on Elective Affinities comprised a column for phlogiston and a lengthy entry was dedicated to exploring its nature and chemical functions.495 In 1787 Kirwan published his first version of the Essay on Phlogiston, presenting his phlogistic experiments and

491 Nicholson (1792), p. 91. 492 Priestley, (1775), p. 133. See Toulmin (1957). As mentioned above (p. 186, fn. 389), the decomposition and synthesis of water was another instance of a ‘crucial’ experiment in the Chemical Revolution. 493 A revised version of the 1773 memoir entitled “Sur une nouvelle théorie de la calcination et de la réduction des substances métalliques sur la cause de l’augmentation de poids quelles acquièrent au feu et sur différens phénomènes qui appartiennet à l’air fixe”; printed in Fric (1959), pp. 155- 162. See also Holmes (1998), pp. 30-40 and Perrin (1986). 494 The work was initially published in 1777 as Chemische Abhandlung von der Luft und dem Feuer. It was prefaced by Torbern Bergman. In 1780, critical notes by Richard Kirwan and a letter by Joseph Priestley were appended; it was translated into English by J. R. Forster and republished Chemical Observations and Experiments on Air and Fire. (See above pp. 191-192, fn. 401). 495 On Bergman’s work on affinities, which represented the most advanced contemporary effort of its kind, see Kim (2003), pp. 258-269; see also Schufle (1985) and Berreta (1988).

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stipulations while analyzing and critiquing the Lavoisians’ work.496 Similarly, phlogiston was accorded an entry in the 1795 Dictionary of Chemistry of Nicholson, the English translator of the Lavoisians’ replies to Kirwan’s Essay.497 As late as 1800, Fourcroy was still enumerated the friends and foes of “the new doctrine of the French chemists”;498

Priestley, among the foes, was to remain a lifelong vocal supporter of the phlogistic cause.499

My present interests, however, are not in phlogistic theories or their various manifestations and versions, some of which have been discussed earlier.500 I wish to examine and extract from the arguments advanced by phlogiston’s dwindling supporters, during the latter stages of the Chemical Revolution, what it was that they found inadmissible in the new chemistry and what of traditional phlogistic chemistry they were unwilling to surrender. This will translate into a broad examination of the chemical- phlogistic outlook as it manifested itself during the peak of the crisis in eighteenth-century chemistry. Increasingly defensive, the late phlogistians rarely questioned the merit of the new theory and the experiments adduced in its support; nor did they undermine the competence of its promulgators. What their arguments reflect is rather a clear sense of loss; one may say, a sense of “despair.” The new chemistry was coming at too high a price. In exchange for what Kirwan dubbed a “false shew of simplicity,” the chemist was forced to abandon ontological assumptions and epistemological practices that were

496 See above, pp. 183-184. 497 Nicholson (1795), II, pp. 639-649. 498 Fourcroy (1788), I, pp. xiv-xv. 499 Cf. Conlin (1996); see also Verbruggen (1972). 500 For the variety of phlogiston theories, especially in the later part of the eighteenth-century see Partington & McKie (1981).

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essential to chemistry.501 This is what is embodied in the ontological concern and uncertainty shared by St. John, Priestley, Nicholson and even Fourcroy.

Unlike the previous chapters, which consisted of in-depth analyses of relatively limited case studies, the present discussion comprises a broader inquiry into what late eighteenth-century pneumatic chemists revealed as their most cherished assumptions and practices, as displayed during the most critical period in the history of eighteenth-century chemistry, a time during which chemical discourse was vigorously challenged. The old truths of chemistry were no longer self-evident, and its practitioners were forced to reflect upon their science and explicate it to themselves, their audience and their rivals. Such reflections are prominent in what are commonly depicted as the phlogistians’ last-ditch attempts to save the existence of a non-isolable, allegedly hypothetical and superfluous entity or a “vague principle, lacking a rigorous definition… adaptable to all explanations… a veritable Proteus,” in Lavoisier’s words.

“RED VAPOURS” VS. “ABSOLUTE FACTS”

Notably, it is the existence of phlogiston, rather than any of its hypothetical qualities that was being defended. According to Nicholson, in 1792, the claim that during calcination metals “[unite with] the vital part of the air” ceased to be a matter of debate.

All that phlogistians still insisted upon was that this process also involved “phlogiston

[being] disengaged.”502 Fourcroy made a similar claim from the opposite perspective.

501 Kirwan (1789), p. 8. 502 Nicholson (1792), p. 160.

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“All chemists are of course agreed” he exclaimed, that the “phlogiston of Stahl … exists,” yet the phlogistians are wrong in everything else they maintain about this entity:

What proves that they are not in the true road to truth, is, that each phlogistian has framed a particular theory of his own, which has little or no relation to any other theory; so that there are now nearly as many theories, as many different kinds of phlogiston, as there are defenders of phlogiston.503

The tenor of Fourcroy’s description is evocative of Kuhn’s account of crisis, in which,

“scientists take a different attitude toward existing paradigms, and the nature of their research changes accordingly. The proliferation of competing articulations, the willingness to try anything, the expression of explicit discontent… [are all] symptoms of a transition from normal to extraordinary research.”504

Even Priestley, traditionally regarded as the “last important defender of phlogiston” or “the most relentless opponent of the antiphlogistic theory,”505 conceded in a 1796 attempt to re-kindle the phlogistic debate, that he did not have a distinct concept, let alone a “particular theory,” of phlogiston. He was explicit, nevertheless, about the general dynamics of pneumatic processes, suggesting that,506

503 Fourcroy (1788), I, pp. xvi-xix. 504 Kuhn (1962), p. 90. 505 Levere &Turner (2002), p, 196; Siegfried (1988), p. 35. 506 Holmes suggested a reformulation of our understanding of Priestley’s phlogistic interests by situating them within a “novel” pneumatic framework which Priestley himself established and which did not owe its origins to Stahlian precepts; within this framework, Priestley’s theoretical commitments to phlogiston were secondary and loosely defined. Holmes maintains that Priestley’s phlogistic perceptions, comprised little more than “scattered responses to particular observations… not connected into a broader framework.” Holmes (2000), p. 748. For a discussion of the slight historiography, privileging the merits of Priestley’s phlogistic defense over Kirwan’s see Boantza (2008); see introduction to chapter 2.

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In all other cases of the calcination of metals in air, which I have called the phlogistication of the air, it is not only evident that they gain something, which adds to their weight, but that they likewise part with something.507

“Something” was lost, the precise nature of which Priestley did not venture to define. He was willing to accept, moreover, the antiphlogistians’ crucial claim: that metals absorb or, in his words, “gain something” during their calcination. What he was unwilling to forgo, however, was the conviction that they “likewise part with something.” Some physical, material substance must be admitted, even if its particular import in the chemical process has radically changed. Priestley went on explain the necessity of this assumption:

The more simple of this processes is the exposing iron to the heat of a burning lens in confined air, in consequence of which the air is diminished, and the iron becomes a calx. But that there is something emitted from the iron in this process is evident from the strong smell which arises from it… and this is the substance, or the principle, to which we give the name of phlogiston.508

The smell emanating from the metal undergoing calcination cannot and should not be ignored. It signals “something”—“to which we give the name of phlogiston”—before and independently of what that thing is. The undeniable sensual experience implied, for

Priestley, an indubitable material existence. Priestley’s reasoning was not an isolated instance. Johan Christian Wiegleb, for instance, German pharmacist and chemical educator, advanced a similar point in asking, rhetorically: “would it be reasonable to

507 Priestley (1796), p. 42. 508 Priestley (1796), p. 42; italics in original.

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question the existence of [an inflammable] principle, because one cannot pick it up immediately?”509

I think not, since experience proves that during the calcination of metals, or while other bodies burn with a flame, a particular matter, sensitive to the sense of smell, spreads through the air, and it must be the same one upon which the inflammability of these bodies depends; because the latter, having been stripped of this principle, are either entirely consumed, or cease to be flammable.510

The perhaps unexpected concurrence between the likes of St. John, Wiegleb and Fourcroy indicates that there was more to Priestley’s point than an old man’s desperate clinging to a defunct, pre-theoretical perception of what the essence of inflammability or combustibility might be. Chapter 2 discussed several of Priestley’s methodological motivations in the context of his experimental practice and SER; chapter 3 dealt with chemical pneumatic metaphysics and examined Priestley’s role in the evolution of the British model of air(s), which peaked, while being compromised, with Kirwan’s theory of phlogiston. Let us now turn to examine further aspects of the chemical practice and epistemology of both Priestley and Kirwan; the latter’s phlogistic summa, his Essay on Phlogiston will examined in greater detail. As far as Kirwan is concerned, I pay special attention to his distinctly chemical views (aspects of his chemico-physical compromise have been dealt with in chapter 3). Setting both pneumatic-phlogistic chemists against the broader backdrop of the

509 For details on Wiegleb’s life and work see Partington (1961-70), III, pp. 567-569. See also Hufbauer (1982), pp. 88-92. 510 Wiegleb (1792), p. 84: “Serait-il raisonnable de mettre l’existence de ce principe en doute, parce qu’on ne peut le recueillir immédiatement? Je réponds par la négative car l’expérience prouve que pendant la calcination des métaux, ou pendant que d’autres corps brûlent avec une flamme, il se répand dans l’air une matière particulière sensible à l’odorat, et qui doit être la même dont dépend l’inflammabilité de ces corps; car ces derniers ayant été dépouillés de ce principe, sont ou entièrement consumés, ou cessent d’être inflammables.” italics added.

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chemical pneumatic community will further facilitate our establishment of eighteenth- century chemical SERs.

Priestley’s intimations concerning the dynamics of pneumatic processes reflect an underlying perception concerning the nature of the chemical substance and its place and function within the chemical process. Kirwan, the most prominent spokesman of the late phlogistic camp, reasoned along similar lines, claiming in his Essay that,

If a solution of mercury in the nitrous acid be dropped into common marine acid, it forms white precipitate, which is phlogisticated, since it affords red vapours, when re-dissolved in the nitrous acid. But if the nitrous solution of mercury be dropped into dephlogisticated marine acid, it forms sublimate corrosive, which does not give red vapours when the nitrous acid is poured on it.511

The “red vapors” are a sign of phlogistication—and hence of phlogiston—which, like the smell mentioned by Priestley and Wiegleb, cannot be ignored, for they signal the presence of a material entity. This presence, so vivid and unquestionable to the traditional chemist, is absent in the new chemistry. Responding to Kirwan’s analysis of the marine (muriatic) acid, Berthollet ignored the “red vapours” altogether, asserting that, “if hydrogene

[Kirwan’s phlogiston] exists in the muriatic acid, there is no fact which shows its existence.” Once the vapors and their particular color are rendered as “no fact,” Berthollet was justified in asking: “is not the phlogiston therefore that [Kirwan] supposes, an useless being, which has no influence in any of the phenomena we have endeavoured to explain, relating to the properties of the oxygenated muriatic acid?” 512

511 Kirwan (1789), pp. 128-29; italics added. 512 Kirwan (1789), p. 135.

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Phlogiston was “an useless being” because “red vapours” are “no fact.” In the new chemistry facts were of a different order than vapors, their colors or smells. The

“explanation of what happens in calcination,” Berthollet noted, together with the other authors of the Method, “is not an hypothesis, but the result of absolute facts,” which are established in a particular and distinct fashion:

It was then proved that in the calcination of metals, either under bell- glasses, or in closely stopped vessels and with certain quantities of air, the air becomes decomposed, and the metal becomes augmented in its weight by a quantity precisely equal to that of the air absorbed.513

“Absolute facts,” then, were for the new chemistry “certain quantities,” the results of precise weighing of the outcomes of processes in carefully enclosed systems.514 The competing analyses of aqua regia (concentrated mixture of nitric and hydrochloric acids) exhibit a similar discrepancy. Advancing a causal explanation, Kirwan referred to qualities picked up by the senses, suggesting that, “part of the nitrous acid is converted into nitrous air, which immediately unites to the undecomposed part of the nitrous acid, and forms phlogisticated nitrous acid, and hence the red colour of the liquor.”515 Berthollet’s response, in contrast, consisted of a strictly quantitative analysis. “The part of the muriatic

513 Berthollet & Fourcroy & de Morveau (1788), p. 221. 514 In her thorough study of the concept of affinity Kim stresses that the difference between Kirwan and Lavoisier could not be ascribed to Kirwan’s disinterest or incompetence in quantitative analysis—quite the contrary. Concentrating on Lavoisier’s perspective of the controversial issues, she comments only on Kirawn’s empirical arguments and not on their intellectual motivations: “Kirwan’s entire critique of the antiphlogistic camp rested on precise measurements of specific weights. He was in fact one step ahead of his French opponents in advocating the importance of these measurements for chemical theory… Lavoisier differed from Kirwan not in his deeper commitment to the rule of the balance but in his algebraic vision of chemistry and in his grammatical understanding of nature. That is, the superior explanatory power of his system lay in the interlocking algebra of all the components, rather than in its application to particular cases at hand.” Kim (2003), p. 380. 515 Kirwan (1789), p. 138; italics added. Cf. Roberts (1995).

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acid, which combines with the oxigene,” he reasoned, “does not remain in the liquid, but is disengaged, and maybe received in proportion as it is formed, at the expense of part of the oxigene.”516 Attention to vapors, colors and smell, Berthollet further noted, with less respect than usual, is not only spurious but is positively misleading:

It is with great reason that Mr. Kirwan finds it surprising, that the muriatic acid of the aqua regia can remain united in the oxygenated state with a small quantity of the nitrous acid ... it is enough to have taken notice of its extremely penetrating smell and its great disposition to fly off in vapours ... the author therefore has a mere supposition, when he affirmed that the volatile alkali is destroyed in the preparation of aqua regia by the amoniacal muriate; which is so far from being well founded.517

This is not to suggest that the phlogistians had any qualms about the chemical practice of weighing or the implementation of precise techniques of measurement.

Nicholson, for instance, emphasized that, “the beginning and end of every exact chemical process consists in weighing.”518 Furthermore, the phlogistians acknowledged the great advance in weighing procedures introduced by the antiphlogistians. Lavoisier, Kirwan commended, is “a philosopher of great eminence, who was the first that introduced an almost mathematical precision into experimental philosophy.” Nicholson, the English translator of the Lavoisians’ replies to Kirwan’s Essay, however, suggested treating some of these claims to accuracy with caution:519

it happens, however, most commonly, in the determination of weights, which is half the business of a chemist, that an account of the admission of elements of specific gravity, carried to too many places of figures … or

516 Kirwan (1789), p. 142. 517 Kirwan (1789), pp. 142-143; italics added. 518 Nicholson (1792), p. 59. 519 Kirwan (1789), p. 7; On the Lavoisians’ ‘rhetoric of precision’ see Golinski (1994); Golinski (1995).

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sometimes from actual noting of weights to a degree of minuteness which experiment cannot justify, we find the results to exhibit an unwarrantable pretension to accuracy.520

Nicholson’s ironic attitude towards the rhetoric of precision conveys the phlogistians’ discomfort with the subjection of all chemical experimentation to weighing and with the conceptions of matter and of chemical knowledge implied by this reduction. As significant as “the determination of weights” may be for the chemist, it can become the ultimate empirical tool only if one assumes homogeneity in the material infrastructure of chemical phenomena. For the uncontested observation that bodies gain weight in combustion to become a decisive argument against the existence of phlogiston—and its corresponding theoretical and practical framework—one has to accept that matter is homogenously heavy, so that every increase in weight indicates the addition of matter and any loss of matter corresponds directly to loss of weight. Such assumptions of homogeneity, however, were in contrast with the chemical SER of someone like Priestley (or Duclos), whose chemical pride derived from an intimate familiarity with differences and particularities, which for him comprised the chemical realm. Substances, in the chemistry defended under the phlogistic banner, are first and foremost particular entities, and since their chemical functions are irreducible to the manifestations of a homogeneous material substratum, neither their presence nor their absence can be inferred solely from the detection of weight changes and exchanges. Weight computations cannot comprise the ultimate analytic tool in chemistry

520 Kirwan (1789), p. vii.

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“Because the calx of mercury derives its additional weight from dephlogisticated air,” Priestley protested,

the antiphlogistians have too hastily concluded that all metallic calces derive their additional weight from the same cause. But this is not by any means a just inference. For the calces of some metals are, in this and other respects, very different from one another, and even the different calces of the same metal.521

This is why the traditional chemists, the phlogistians, refused to ignore smells and colors and why they insisted on interpreting those as a sign of “something,” a chemical entity.

Every substance consisted of unique properties and every chemical phenomenon was an effect of causal processes involving particular substances endowed with such unique properties. Chemical knowledge, for Bergman, just as for Priestley, Scheele, Duclos or

Lewis, as we have seen, was predicated upon the study of these properties through an array of empirical procedures, consisting of various phenomenological expressions, as Bergman noted:

the knowledge of the form, taste, solubility, tendency to effloresce, and other properties ... of the substances, is of great use in enabling us to judge ... whether any, and what decomposition has taken place.522

Like other phlogistians, Bergman was not opposed to chemical accuracy or careful mathematical representation noting, nevertheless, that, “a more accurate measure of

[attraction], which might be expressed in numbers, is as yet a desideratum.”523 Yet aspiring to greater accuracy in chemical practice and theory cannot justify the reduction of

521 Priestley (1800), p. 15; italics added. 522 Bergman (1785), p. 65. 523 Bergman (1785), p. 4.

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matter to sheer bulk; of chemical phenomena to the aggregation of mass; or of the wide variety of chemical experimental practices to weighing. Echoing Priestley’s lamentations,

Bergman observed how “smell also often indicates what is taking place,” and how “the taste likewise often informs an experienced tongue.”524

Priestley’s arguments concerning the interpretation of the famous experimetum crucis with the calx of mercury demonstrates how fundamental this SER was for the defense of phlogiston and phlogistic chemistry in general.525 Priestley allowed that,

“mercury revived either by inflammable air or in close vessels has the same properties will not be denied; and if so, it must consist of the same principles, and in the same proportion, or nearly so.” According to Kirwan, “inflammable air,” it will be recalled, was nothing but phlogiston in an aerial (gaseous) state. And not unlike Scheele in his view of more than two decades earlier, Priestley assumed that, “phlogiston passes … thro’ the glass when the calx is revived.”526 According to the traditional chemistry, Nicholson surmised, “metals, like all other inflammable bodies, contain phlogiston united to a base.”527 Priestley was even willing assume for the sake of argument that the antiphlogistians were correct and that the “difference between the calx [of mercury] and the metal, is that the latter [the mercury] has parted with the air which it had imbibed.” For this, however, to be a “proof that metals are simple substances,” and that calcination does not involve the release of phlogiston, one has to conclude that this is true “in all other cases of calcination, as well as

524 Bergman (1785), p. 67. 525 See fn. 492. 526 Priestley (1800), p. 35. 527 Nicholson (1792), p. 131.

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this.” Priestley deemed such reasoning to be patently false, for “this is the case of only this particular calx of this metal.”

Homogeneity of substances cannot be inferred from similarity in appearances,

Priestley stressed, for “though with the same external appearance,”

the same metal may contain different proportions of any particular principle, as phlogiston, they must be denominated different substances, if some specimens contain this element, and others be wholly destitute of it. All, therefore, that can be inferred from the experiment with the precipitate per se is, that in this particular case, the mercury in becoming that calx imbibed air, without parting with any, or very little of its phlogiston… mercury may have the same external appearance, and all its essential properties, and yet contain different proportions of something that enters into it.528

What the antiphlogistians considered a cornerstone in their reinterpretation of pneumatic processes—inferred directly from rigorous computations in close accord with the principle of weight conservation—was for Priestley a mere instance of a “particular case.”

Mercury’s specific constitution, in this “particular case” or chemical reaction allowed it to absorb air while parting with almost no phlogiston; such were the “proportions” of its

“particular principle[s].” Even “different proportions” of constituents do not necessarily entail a change in a substance’s essence. After all, Priestley concluded by way of question,

“what is the evidence of a change in the nature of any thing, but a change in its properties?”529

The insistence on particularities as the foundation for chemical knowledge was what led Priestley to reject the Lavoisians’ interpretation of another crucial experiment: the

528 Priestley (1796), pp. 39-41; italics added. 529 Priestley (1796), p. 49; italics in original.

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synthesis and decomposition of water. This, the phlogistians had to admit, was a strong argument against their standpoint and SER, as Kirwan remarked, concerning the synthesis of water:

[phlogiston is] no longer to be regarded as a mere hypothetical substance, since it could be exhibited in an aerial form in as great a degree of purity as any other air. This opinion seems to have met the approbation of the most distinguished philosophers… nor can I see what Mr. Lavoisier could reply, before the important discovery of water made by Mr. Cavendish. This furnished him with a new and unexpected source from which he could derive the inflammable air.530

Like Kirwan, Priestley did not deny that water was a compound that can be decomposed and recomposed, analyzed and synthesized. He even seems to have accepted the

Lavoisians’ account of what takes place in the experiment itself:

The proof that water is decomposed, and resolved into two kinds of air, is that when steam is made to pass over red-hot iron inflammable air is produced, and the iron acquires an addition of weight, becoming what is called finery cinder; but what they [the Lavoisians] call oxide of iron.531

Priestley, however, could not consider this experiment as an instance of oxidation; that would equate it with other processes that according to the antiphlogistians were similar chemical instances—of the same oxidation—such as rusting. An identification of this sort flies in the face of fundamental chemical knowledge, as Priestley understood it; he maintained instead that, “common rust of iron, has a very different appearance from this finery cinder, being red, and not black.” Appearances, then, stand for properties and properties comprise substances. Consequently, even Fourcroy’s explanation that, “iron is

530 Kirwan (1789), p. 5. 531 Priestley (1800), p. 42.

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partially oxygenated” was unacceptable to Priestley: it implied that “common rust” and

“finery cinder”532 are essentially the same substance, differing only in that they exhibit varying degrees of oxygenation. But the different properties of rust and cinder, according to Priestley, demonstrated their essentially different “nature”: “iron in this state is saturated with some very different principle, which even excludes that which would have converted it into rust.”533

It is important to note that Priestley’s underscoring of differences and particularities is not just a stubborn anti-theoretical or empirically naïve stance.534 His rejection of

Fourcroy’s analysis was based on a distinctly theoretical observation. As we have previously seen, Priestley as well as other pneumatic chemists, subscribed to the idea of air(s) transmuting into different aerial entities upon the loss and gain of phlogiston;

(de)phlogistication was perceived as process of pneumatic transmutation. Since this does not hold true of metals and other solids, the addition or subtraction of a ‘principle’ could not be seen as changing their nature “partially.” This distinction between air(s) and metals illustrates a fundamental difference between traditional phlogistic chemistry and the new

French chemistry, according to which air and vapors represented particular substances as much as they expressed a state of matter. We have also seen Kirwan’s chemically risky attempt to claim both ontological statuses for phlogiston. For Lavoisier each gas was a different chemical species whose involvement in chemical processes was as different as that of various solids and liquids. Solids combined with solids, liquids, and airs in the

532 Finery: A hearth where cast iron is made malleable, or in which steel is made from pig-iron. (Oxford English Dictionary). 533 Priestley (1796), pp. 46-47. 534 See above pp. 144-150.

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same fashion as airs combined with airs. The state of the body was irrelevant in this context.

“CERTAIN QUANTITIES” VS. “PROPORTIONS”

Espousing a phlogistic SER in reaction to Lavoisier’s assault meant, among other things, defending a concept of a chemical substance as a particular species of matter, endowed with substantial qualities irreducible to quantities of homogeneous bulk.535 This, however, did not preclude thinking about chemical substances in terms of relative proportions and combinations, for “the same substances in different combinations, and in different states, have different properties” and “substances possessed of very different properties may be composed of the same elements, in different proportions, and different modes of combination.”536 Indeed, according to the basic pneumatic phlogistic principles, as discussed in chapter 3, combustibility and inflammability of bodies were functions of their varying phlogistic contents. This was observed in both the British and Swedish pneumatic transmutational sequences. The French, in contrast, interpreted chemical changes in terms of the interactions of combinations of definite, distinct, and homogeneous substances; changes in chemical properties corresponded to changes in the definite chemical compositions of bodies.537

535 For an insightful study of “substances” in eighteenth-chemistry, focusing on various technologies of their preparation, manipulation and especially classification, see Klein & Lefèvre (2007). 536 Priestley (1800), pp. 35-36. 537 Langer (1971), p. 6.

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The “kinds of air,” Priestley asserted, “differ chiefly in the quantity of phlogiston.”

At the same time, the quantitative differences produce differences in pneumatic “kinds”

(strictly aerial kinds in Priestley’s case). The “gradation” of phlogiston, moreover, did not stand solely for its different relative amounts, although it was that as well. Rather, it implied the level of an air’s (im)purity or its ability to support respiration and combustion.

The dual two-ended process of (de)phlogistication did not consist solely of an arithmetic addition or subtraction of quantities of phlogiston but entailed a transmutation, by which one kind of air turned into another, following regular and constant sequences such as dephlogisticated, common, phlogisticated and nitrous airs, to recall Priestley’s basic sequence. The various steps of this sequence were distinguished chiefly by the various quantities of phlogiston. Yet the quantities of phlogiston explain the distinct properties of each of the distinct airs; as such, they were expressions of these steps as much as they were their causes.538 To wit, although expressed in terms of quantities of phlogiston, it was the process of phlogistication that Priestley described and analyzed, a process he had interpreted as a transformation of aerial qualities. In his account of the nitrous air test, designed to evaluate what he referred to as the “goodness” of a given air, Priestley employed a similar SER.539 After explaining how to perform the test by mixing different airs with nitrous air, then measuring the diminution in aerial bulk, Priestley added that,

“any other process by which air is diminished and made noxious answers the same purpose

… In fact, it is phlogiston that is the test.”540 This type of status—accorded to

538 Priestley (1775), p. 392. See above pp. 190-191. 539 See Levere (2000). 540 Priestley (1775), p. 208.

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phlogiston—shows why the demand to isolate phlogiston, which became a major turning point in the Chemical Revolution (at the hands of the Lavoisians),541 could be rendered at times as a categorical misinterpretation of chemical knowledge, as Richard Watson pointed out in 1781. In his answer to the question—“what is phlogiston?”—Watson exposed the fallacy:

you do not surely expect that chemistry should be able to present you with a handful of phlogiston, separated from an inflammable body; you may just as reasonably demand a handful of magnetism, gravity, or electricity to be extracted from a magnetic, weighty, or electric body; there are powers in nature, which cannot otherwise become the objects of the sense, than by the effects they produce, and of this kind is phlogiston.542

The difference between phlogiston and other imponderable entities, such as light and caloric, expounded by the new chemistry, was not that the latter were less hypothetical or more immediately quantifiable. In this context, Lavoisier’s use of caloric may seem symmetrical to Priestley’s use of phlogiston:

the same body becomes solid, or fluid, or aëriform, according to the quantity of caloric by which it is penetrated; or ... according as the repulsive force exerted by the caloric is equal to, stronger or weaker than the attraction of the particles of the body it acts upon.543

But whereas Lavoisier’s quantities of caloric put “the same body” into different states,

Priestley’s “gradation[s]” of phlogiston produced different substances, which transmuted into one another. As seen, pneumatic chemists like Priestley, Scheele and Kirwan all subscribed to the notion of transmutational sequences, even though, as Fourcroy

541 As exemplified by Kirwan’s approach, which mostly revolved around endowing phlogiston with a material existence. 542 Watson (1787), I, p. 167. 543 Lavoisier (1790), p. 7.

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complained, there was little agreement concerning the specific products involved. The difference between the sequences has been discussed in chapter 3: whereas Priestley’s sequence consisted of four kinds of airs (dephlogisticated, common, phlogisticated, and nitrous), Scheele, for instance, stipulated a sequence including his analogue of dephlogisticated air, light, heat and inflammable air; the latter, inflammable air, Scheele’s most phlogisticated entity, was later advanced by Kirwan as phlogiston in an aerial state

(or phlogiston gas).

Bergman and Priestley shared Lavoisier’s aspiration for quantitative accuracy. But the explanatory role Lavoisier had assigned to quantification militated against the traditional chemists’ basic concept of matter. Endowed with different properties, the various “kinds of airs” are ipso facto different substances. They cannot be merely different states distinguished only quantitatively. Put differently, from an ontological perspective, whereas a material state is a physical entity, a substance is a chemical entity. “Dr.

Priestley,” Nicholson observed, discovered “a considerable number of aerial fluids.”

Reflecting upon Priestley’s sequence, Nicholson explained how these airs are distinguished by the degree of phlogistication: “common or atmospheric air,” “fixed air,” “nitrous air.”

They are, nevertheless, distinct substances; particulars endowed with essential properties and not states of the same substance. Whereas for Lavoisier “air is a fluid naturally existing in a state of vapour,” Nicholson argued that “vapours” are mere “elastic fluids or subtle invisible matters which fly from bodies subjected to chemical operation or otherwise,” he noted, “accurate chemical writers confine this appellation to such

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exhalations only as may be condensed into the fluid state by cold.”544 A substance’s ephemeral existence in a particular state was evidently “in contradiction with the aerial fluids of which scarcely any are so convertible by any means in our power.”545 The demarcation between airs—pneumatic entities charged with various quantities

(proportions) of phlogiston—and vapours, was sharply drawn and is suggestive of the demarcation between physically “condensable” matter and chemical matter, which is “not condensable”:

Air is a generic name of such invisible and exceedingly rare fluids as posses a very high degree of elasticity, and are not condensable into the liquid state by any degree of cold hitherto produced. This last circumstance is the only distinctive criterion between air and vapour; for vapour is condensable by cold.546

THE FORCE OF AFFINITY AND AFFINITY AS A FORCE

If the fundamental ontological units of the phlogistians were chemical substances with their irreducible properties, the fundamental relations between them were captured by the unique “paper tool”547 of eighteenth-century chemistry, the affinity table.548 Bergman, the compiler of the most progressive affinity table of his time (see figure 3), provided an example of the type of chemical transformations, captured and represented by such a table:

544 Lavoisier (1790), p. 29; Nicholson (1795), II, p. 959. 545 Nicholson (1795), II, p. 959. 546 Nicholson (1795), I, p. 72. 547 See Klein (1994); Klein (2001). For two outstanding histories of chemical affinity see Kim (2003); Goupil (1991) esp. pp. 89-190 (for the post Newtonian era until the end of the eighteenth- century. 548 For an extensive study of the origins and evolution of eighteenth-century tables of affinity see Duncan (1996).

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Volatile alkali is dislodged by fixed alkali and pure calcareous earth … quicksilver and silver are precipitated from nitrous and vitriolic acids on the addition of copper, which is again separated by iron. Silver, quicksilver and lead … are separated from nitrous acid both by the vitriolic and marine. Do not these … shew, that there prevails a constant order among the several substances?549

The affinity table was perhaps the most conspicuous tool and representation of phlogistic chemistry to be retained by the Lavoisians. Their conception of chemical affinities and their respective manner of their application, however, failed to impress Kirwan, who remarked that,

To explain the precipitation of metals dissolved in acids by other metals, Mr. Lavoisier thinks it sufficient that the oxigenous principle should have a greater affinity to the precipitant than to the precipitated metal ... But the phenomena of precipitation are much more complicated.550

This may seem a harsh assessment of Lavoisier’s work on affinities (see figure 3).

Lavoisier was aware that, “the table of affinities of the oxigenous principle with the different substance” is far from perfect; he added that, “Mr. Kirwan … does not judge me with more severity than I do myself.”551 Yet Kirwan’s complaint, as always, did not concern the antiphlogistians’ competence but the chemical principles—metaphysical and epistemological—underlying their SER, and even more so, the principles that they reject and exclude from their SER.

549 Bergman (1785), p. 11. Cf. Kim (2003); Goupil (1991). 550 Kirwan (1789), pp. 244-246. 551 Kirwan (1789), p. 46.

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Figure 3. On the left: “Single Elective Attractions” from Bergman’s 1785 Dissertation (phlogiston in column 36); on the right: Lavoisier’s ”table of oxygenous principle” from Kirwan’s 1789 Essay. Comparing the two tables demonstrates the visual dimension of the reduction from the ‘richness’ of phlogistic traditional chemistry to the ‘bareness’ of the French system.

Lavoisier conceded that affinities were complex and difficult to pin down, admitting that

“the force of affinity, which unites two principles,” for example, “is not the same in … two degrees of saturation.”552 Yet it is a “force”; not a quality of any particular substance, but a unifying principle of nature, subject to mathematical laws which are simple and precise even if difficult to discover: “affinity is a variable force, which decreases according to

552 Kirwan (1789), p. 51.

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certain laws, not yet determined.”553 This concept of force clarifies Kirwan’s refusal to identify with or accept the new chemistry’s conception and use of affinities.

The term force, nonetheless, did have a natural place in the old system of affinities as well. “In this dissertation,” Bergman announced at the beginning of his work on affinities, “I shall endeavour to determine the order of attractions according to their respective force.”554 Moreover, in the homage to Newton with which he commenced his work, Bergman made it clear that he well understands the concept of force as a universal presence governed by simple mathematical laws.555 For Lavoisier, the two uses of “force” should coincide, at least in principle; attractions and elective affinities should be understood along the lines of Newtonian gravity: “two forces, both of which are variable; the first, according to a certain law dependant of temperature; and the second, according to the distance.”556 Bergman, however, would hardly confuse this universal simplicity of mathematical law-governed gravity with the complexity of the attraction of affinity. For him, the former was but a second-order property, a measure of the affinities or attractions between substances. In other words, for Lavoisier “force” was a physical entity as well as a unifying principle. For Bergman, attractions were properties of substances while force was the measure of their difference.

What the phlogistians resisted, then, was not the replacement of one hypothesis with another, nor the introduction of “mathematical precision into experimental philosophy,” as Kirwan framed Lavoisier’s contributions. What the proponents of

553 Kirwan (1789), p. 252. 554 Bergman (1785), p. 4. 555 Bergman (1785), pp. 2-3. 556 Kirwan (1789), p. 46.

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chemistry as an autonomous discipline refused to accept was the idea that the unifying principle of nature consisted of, in essence, a simple material infrastructure governed by simple mathematical laws. What they tried to maintain, in their concept of affinity as well as other aspects of their SER, was regularity of cause and effect, rooted in the qualities of individual substances that were, at the same time, wholly embedded in continuous chemical processes:

By chemical operations or processes, we mean the application of the proper means to affect the decomposition or composition. Every one of them is grounded on the various degrees of affinities of heterogeneous substances amongst each other.557

Affinities, a chemist like Friedrich Gren558 asserted in 1800, could not be perceived outside

“chemical operations or processes.” Their “various degrees,” moreover, did not follow independent mathematical laws but the relations “amongst heterogeneous substances.”

Such substances, Bergman explained, were “heterogeneous” by virtue of possessing different qualities:

When homogeneous bodies tend to union, an increase of mass only takes place, the nature of the body remaining still the same; and this effect is denominated the attraction of aggregation. But heterogeneous substances, when mixed together, and left to themselves to form combinations, are influenced by difference of quality rather than quantity. This we call attraction of composition559

557 Gren (1800), I, p. 50. 558 For details on Gren’s life and work see Partington (1961-70), III, pp. 575-577. For an extensive and informative discussion of Gren’s phlogistic work and the various criticisms adduced against it during the last two decades of the eighteenth-century see Partington and McKie, Historical Studies, 3rd article. See also Hufbauer (1982), passim. 559 Bergman (1785), p. 5.

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Lavoisier’s interpretation of the issue is revealing. Justifying his own “table of affinities,” in reaction to Kirwan’s critique, he argued that,

A principal defect, common to all the tables of affinities which have hitherto been made consists in their presenting only the results of simple affinities, whereas there exists only in nature… cases of double affinity, often triple, and others perhaps still more complicated.560

And in order “to form accurate ideas respecting these phenomena,”

it is necessary to consider all the bodies in nature as plunged in an elastic fluid of great rarity and lightness… [known as] the principle of heat… [which] would separate them [their parts] if they were not retained by their mutual attraction, that is to say, the attraction which is commonly called the affinity of aggregation.561

Once more, we see how and why there was no place for “heterogeneous substances” in

Lavoisier’s system. They were not only conveniently ignored; they were intentionally done away with. Difficulties arising from such types of unions were to be resolved by regarding all bodies in nature as abiding by the sole rules of “aggregation.”562 Both

Bergman and Lavoisier, then, had recourse to the concept of aggregated matter. Yet even the difference in their particular phrasings is instructive. Bergman paired “aggregation” with “attraction,” distinguishing it from “attraction of composition,” as the other type of possible combination: the chemical. This distinction was altogether lost on Lavoisier who, like Boyle before him, blurred the division between the chemical and the physical, referring to the “affinity of aggregation” as the only existing type of combination. For him, there existed only one kind of chemical “affinity”—that of “aggregation”—which

560 Kirwan (1789), pp. 45-46. 561 Kirwan (1789), p. 45. 562 Kirwan (1789), pp. 45.

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was physical and universal to “all the bodies in nature” and abided by the (Newtonian) laws of “mutual attraction.” This was how the chemical complexity of affinities and their particularities, as entailed by their relational character, were replaced by “accurate ideas.”

This accuracy hardly served to settle Kirwan’s worries. He complained that the

“simplicity” of the “antiphlogistic hypothesis… though seducing in some cases, becomes insufficiency in many others. I pass over many other embarrassing objections…” (see below).563

Bergman’s table is at once a tour de force and an admission of the limits of chemical knowledge. It is an attempt at the highest level of formalization attainable, given the limited regularity of chemical processes and their irreducible complexity. In fact, this complexity is the one most distinctive characteristic of affinities. Justifying “the necessity for a new Table of Attractions,” Bergman wryly admitted:

I am very far from venturing to assert, that that which I offer is perfect, since I know with certainty, that the slight sketch now proposed will require above 30,000 exact experiments before it can be brought to any degree of perfection. But when I reflected on the shortness of life, and the instability of health, I resolved to publish my observations, however defective, lest they should perish with my papers.564

UNIFORMITY VS. SIMPLICITY

It is not because affinities were lost on the new chemistry that the adherents of “the old system” complained.565 Quite the contrary, as Kirwan (still in his phlogistic mode)566

563 Kirwan (1789), p. 249. 564 Bergman (1785), pp. 69-70. 565 Kirwan (1789), p. 167. 566 On Kirwan’s capitulation see Mauskopf (2000); Boantza (2008).

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admitted that some accounts by chemical affinities are much more suited to “the antiphlogistic hypothesis”; he observed: “why iron precipitates copper from the vitriolic acid, may be explained in the antiphlogistic hypothesis, since iron is said to have a greater affinity to the oxigenous principle than copper has, and also to take up more of it.”567 Yet

Lavoisier’s analysis by affinities to which Kirwan alluded was strictly quantitative. In one of his responses to Kirwan’s Essay, Lavoisier suggested that,

I proved that whenever one metal was precipitated by another, and re- appeared under the metallic form, ... the precipitating metal had taken the oxigene from the precipitated metal, and that by comparing the respective quantities of the two metals employed, a conclusion must be made of the quantities of oxigene necessary for the dissolution of each metal in the acids.568

Lavoisier, again, merged together distinctly chemical patterns—such as the recovery of substances by precipitation—with a quantitatively dominated SER. Lavoisier sought to infer the chemical (substances, nature of reactions, etc) from the physical (ultimately represented by quantities). Kirwan found this type of analysis to be lacking, ignoring much of the crucial phenomena to be accounted for:

But why copper, which is insoluble in the dilute vitriolic acid should become soluble in a dilute solution of vitriol of iron exposed to the air, or in a boiling heat, seems to me difficult to conceive in the new hypothesis, for the iron should not only retain the oxigenous principle, with which it is far from being saturated, but also take up that which comes from the atmosphere ... [this is one] of the many difficulties in which the antiphlogistic hypothesis is involved. They are sufficient to shew that its simplicity, though seducing in some cases, becomes insufficiency in many other.569

567 Kirwan (1789), p. 248. 568 Kirwan (1789), p. 250; italics added. 569 Kirwan (1789), p. 248; italics added.

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The difference in the understanding of the explanatory role and ontological status of affinity throws into sharp relief the traditional chemist’s dissatisfaction with the new chemistry’s account of combustion and calcination processes, but also with its general perception of what comprises a natural law and its use in chemical explanations.

The difference is best perceived in the use of the term force in relation to affinities.

Lavoisier’s Newtonian allusion in this context was not haphazard. Bergman used

“attractions” to mean affinities in general but he clearly distinguished, as we have seen, between their chemical status—“attractions of composition”—and their physical function—“attractions of aggregation”—as expressions of Newtonian universal gravitation. Lavoisier, contrarily, used both notions interchangeably, intentionally blurring the crucial difference between distinctly chemical properties and the universal physical force:

as the attraction of these particles for each other is diminished in the inverse ratio of their distance, it is evident that there must be a certain point of distance of particles when the affinity they possess with each other becomes less than that they have for oxygen, and at which oxygenation must necessarily take place if oxygen be present.570

Interpreting affinity as an underlying force, identical in all the substances exhibiting it,

Lavoisier could utilize it to replace phlogiston as the general principle of inflammability: where inflammable bodies were the ones containing phlogiston, they were now those possessed of a high affinity to oxygen. “Several conditions are requisite to enable a body to become oxygenated,” Lavoisier explained, “and primarily, that the particles of the body

570 Lavoisier (1790), p. 186.

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... shall have less reciprocal attraction with each other than they have for the Oxygen.”571

This, from a traditional phlogistic perspective, was a hopelessly simplistic and reductive account. Even one type of combustion, like calcination, was a complex process, differing from one substance to another, as Kirwan tirelessly described how “to calcine a metal is to deprive it of its metallic splendor,”

or reduce it to a brittle, less coherent and pulverent form: malleable metals thereby lose their malleability, and mercury its liquidity. To reduce a metal is to restore to it the metallic lustre, and the degree of coherence and malleability peculiar to it ... The differences substances by whose means in different degrees of heat, different metallic substances may be calcined, are respirable air, water, acids, alkalis, mercury, with the assistance of respirable air, and various other metallic substances in different circumstances.572

Yet it is precisely this emphasis on “differences,” the emphasis on the intrinsic complexity of nature that the antiphlogistians challenged in arguing that,

We may justly admire the simplicity of the means employed by nature to multiply qualities and forms, whether by combining three or four acidifiable bases in different proportions, or by altering the dose of oxygen employed for oxydating or acidifying them. We shall find the means no less simple and diversified, and as abundantly productive of forms and qualities, in the order of bodies we are now about to treat of.573

Nature, according to the new chemistry, in accordance with its respective chemical SER, was in essence simple and its diversity is hence produced by equally simple means; chemistry should follow suit. “The method we have adopted,” declared Lavoisier,

571 Lavoisier (1790), p. 185. 572 Kirwan (1789), p. 166. 573 Lavoisier (1790), p. 149.

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“following nature in the simplicity of her operations, gives natural and easy nomenclature applicable to every possible neutral salt.”574

The traditional chemists never denied this feature of the new theory. Kirwan, for instance, readily admitted that it was “recommendable by its simplicity.” Yet he deemed it as a “false shew of simplicity.”575 “The more we succeed in simplifying the principles of bodies, the more difficult it is to determine truly what passes in chemical operations” is the way Nicholson formulated a similar concern.576 Yet the conclusion from the irreducible complexity of chemical processes was not a call for phenomenological skepticism (or for self-imposed modesty of an art vs. a science). Kirwan’s complaint was not that the antiphlogistians tried to explain too much but that they explained too little. The

“simplicity” of their “doctrine” was “insufficiency” not because it offered more order than nature allows, but because, as he asserted in the preface to his Essay, “the ancient doctrine

[is] the more uniform of the two.”577 It is more uniform, Bergman explained, because it pays full attention to the richness of causal relations that bring about natural phenomena:

It is beyond doubt, that the most minute circumstances have their efficient causes; and these causes, for the most part, are so interwoven with the more powerful ones, and so moderate their efficacy, that, without the former, the whole effect cannot be appreciated. In natural philosophy, no observations are trivial, no truths insignificant.578

The chemical subject matter is essentially complex; hence chemical knowledge cannot be reductive. Chemistry requires immediate recognition of the different substances in their

574 Lavoisier (1790), p. 168. 575 Kirwan (1789), pp. 7-8. 576 Nicholson (1795), II, p. 720. 577 Kirwan (1789), p. 8. 578 Bergman (1788), p. xxxiii.

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different states and stages. Not a “false shew of simplicity” but a close acquaintance with substances that allows the perception of uniformities and regularities within the complexity. This is the kind of interpretation of principles and properties upheld by phlogistic chemistry and its corresponding SER. Priestley, the last chemist who actively defended phlogiston, was perhaps the most eloquent in characterizing the type of uniformity phlogistic chemistry offered. Concerning phlogiston he argued that, “it is certainly hard to conceive how any thing that answers to this description,”

can be only a mere quality, or mode of bodies, and not a substance itself, though incapable of being exhibited alone. At least, there can be no harm in giving this name to any thing, or any circumstance, that is capable of producing these effects. If it should hereafter appear not to be a substance, we may change our phraseology, if we think proper. On the other hand I dislike the use of the term fire, as a constituent principle of natural bodies, because, in consequence of the use that has generally been made of that term, it includes another thing or circumstance, viz. heat, and thereby becomes ambiguous, and is in danger of misleading us. When I use the term phlogiston, as a principle in the constitution of bodies, I cannot mislead myself or, because I use one and the same term to denote only one and the same unknown cause of certain well-known effects. But if I say that fire is a principle in the constitution of bodies, I must, at least, embarrass myself with the distinction of fire in a state of action, and fire inactive, or quiescent.579

Just as for Priestley the emanating “smell” signalled the indubitable presence of

“something”—a substantial chemical agent of sorts (be it phlogiston)—so the very same

“thing,” he claimed, cannot be “a mere quality, or mode of bodies.” Its presence and nature are inferred from relations between qualities or chemical “circumstance[s],” which derive from experiments and experiences. Yet it must be a “substance,” and as such an integral part of the material realm, the ultimate subject of chemical knowledge.

579 Priestley (1775-77), I pp. 282-2833; italics in original.

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CONCLUSION

When Kirwan and Priestley, Bergman and St. John, Nicholson and even Fourcroy attempted to save the concept of phlogiston in the 1780s, 1790s and into the 1800s, it was not a particular hypothesis concerning combustion or calcination that they were defending.

They were all aware that the term has already gone through too many changes to designate any one substance and they did not fail to appreciate the achievements of the new chemistry. Their defense of phlogiston was, rather, a defense of a chemical SER that they felt was about to vanish. At the core of this chemical SER stood the knowledge of the world of matter in its complexity; a close acquaintance with the various substances and a knowledge of their heterogeneity and the variety of their causal interrelations. This SER avowed strong empirical commitments and careful attention to phenomenal detail, whence follows a wariness of any experimental or theoretical reductions. Yet none of this implied skepticism or a general distrust of generalizations. Quite the opposite: it is only this kind of knowledge that allows the uniformity of the chemical realm, for it allows the perception of ‘regularities’ within the network of causal relations between substances with similar qualities.

The notions of phlogiston and of oxygen were not symmetrical. To say that all inflammables contain phlogiston was to suggest a unifying hypothesis. To say that they all have affinity to oxygen was only to repeat that they are inflammable. Affinity in the chemical SER as expounded by the traditional chemists was not a cause, it was merely a relation between substances. Affinity tables described elective affinities, relating substances and their specific natures as displayed by their elective chemical behaviors so to speak. The affinity to oxygen requires a cause, “the absolute existence” of which we must

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allow whether, as St John observed, “we call it phlogiston, caloric, or in plain English, fire.”

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“LAWS OF ANOTHER ORDER”: CONCLUDING REMARKS

By 1765 the seventeenth-century Scientific Revolution had long since been fulfilled; the Chemical Revolution was not yet in sight. It was then, we shall recall, that

William Lewis presented some of the differences between “natural or mechanical philosophy” and “chemistry,” suggesting that the latter “considers bodies as being composed of such a particular species of matter… [the properties of which] are not subject to any known mechanism, and seem to be governed by laws of another order.”580 We have also seen that Kuhn observed, over half a century ago (although without properly explaining), how “mechanical metaphysics… [so fruitful to seventeenth-century physics], proved a sterile and occasionally adverse intellectual climate for an understanding of the processes underlying chemical change.”581 It may seem, at first view, that Kuhn’s remark merely echoes Lewis’s complaint. There are two points to be made here, one textual and one contextual. By 1765, the general spirit of disillusionment with the “mechanical philosophy” as applied to “chemistry” was commonplace. Newtonian universal attraction held a distant promise for a quantified chemical science of micro-matter, a dream that was not fulfilled until much later. Yet even a pre-Newtonian chymist like Duclos was acutely aware of the dangers (and uselessness) implied by a reductive mechanization of chymistry.

Read closely, Lewis’s words seem to pertain not only to chemistry’s immediate past but also to its immediate future. Written at the beginning of the latter third of the eighteenth- century, a period which came to be dominated by the Chemical Revolution of the 1770s

580 See fn. 273; italics added. See also Duncan (1996). 581 See fn. 20.

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and 1780s, Lewis’s way of defining chemistry and the chemical vis-à-vis natural philosophy and the physical seems to be almost prophetic when considered in light of phlogistic traditional chemists’ reaction to Lavoisier’s reformation.

It is important to note that in 1765 Lewis still referred to “mechanism” in the context of the “mechanical philosophy.” Yet if we strip and abstract the former from the connotations of the latter, we can ponder whether the Chemical Revolution had more successfully penetrated into the mysteries of this “mechanism.” Lavoisier’s aversion to mechanism—specifically mechanical philosophy and atomism—is well known:

All that can be said upon the number and nature of elements is, in my opinion, confined to discussions entirely of a metaphysical nature. The subject only furnishes us with indefinite problems, which may be solved in a thousand different ways, not one of which, in all probability, is consistent with nature… if, by the term elements, we mean to express those simple and indivisible atoms of which matter is composed, it is extremely probable we know nothing at all about them.582

“We must trust to nothing but facts,” he concluded, since “these are presented to us by

Nature, and cannot deceive.”583 No early modern chemist would have challenged this observation. But while the first part of the passage echoes Boyle’s skepticism, the second part brings Duclos’s metaphysical despair to mind. And given Lavoisier’s reductively quantitative program for the establishment of chemical facts, it is hardly surprising that traditional phlogistic chemists were as disaffected from his reform as Duclos was from

Boyle’s.

582 Lavoisier (1790), p. xxiv. 583 Lavoisier (1790), p. xviii.

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Lewis’s mention of “laws of another order” is telling. Despite Lavoisier’s agnosticism concerning the ultimate nature of matter—and his subsequent definition of the chemical element as the endpoint of chemical analysis—he proceeded to establish a set of supposedly indubitable “facts” as part of his gravimetric algebraic vision. Lewis does not pretend to posses the key to these chemical “laws.” Reserving his judgment, he insightfully pointed out that chemistry, unlike physics, treats the material realm differently, as if it consisted of “a particular species of matter.” Both Duclos and late eighteenth- century phlogistic chemists conveyed the same message in their reactions to the respective

“crises” in early modern chemistry. One of Boyle’s foremost concerns was to rid chymistry of substantial forms and occult forces while rendering matter as inert. Despite his alchemical beliefs in metallic transmutations and angelic supernatural powers (these convictions were kept private and did not make their way into his published philosophical works) Boyle rejected chymical explanations based on action at a distance, a trend common to all mechanical philosophers. Although according to Duclos’s SER matter was essentially devoid of inner activity, it could be activated by agents such as the universal esprit igneé or otherwise be affected by tendencies such as those evinced in his use of the notion of symbole.584 Mere fire and heat, on the other hand, could not endow matter with any sort of inner activity; they merely endowed it with motion at the particulate level. For

Duclos the vegetal and generative heat imparted by the universal igneous spirit was in opposition to the mechanical heat produced by the furnace, as seen in distillation for example: whereas the latter put inactive matter in physical motion, bringing about changes

584 Duclos (1680), passim.

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of one “order,” the former breathed life into the same inert matter, occasioning transformations of “another order.”

In the wake of Newton, rigid mechanistic views have suffered a severe blow and by

1765, when all three parts of Lewis’s Commercium Philosophico-Technicum appeared, affinity was one of the most dominant theoretical as well as operative notions in chemistry.

In allusion to Newtonian gravitation, Lewis clarified that, “to the grand active power, called attraction, in the mechanical philosophy, what corresponds in the chemical is generally distinguished by another name, affinity.” This remark squares well with the opinion of Bergman, expert on chemical affinities, who distinguished between “attraction of aggregation” and “attraction of composition.” More importantly, Bergman ascribed the former to “homogeneous bodies” and the latter to “heterogeneous substances.” Indeed, one of most conspicuous traits of the early modern chymical SER consists in its insistence on keeping this distinction in place. For the early modern chemist, the distinction between homogenous matter and the heterogeneity of substances was of prime importance and comprised one of the ways by which chemistry regarded “bodies as being composed of… a particular species of matter.” The early modern chemists’ insistence on the heterogeneity of the material world and of the particularity of substances is a recurrent theme, seen as much with Duclos as with Priestley, Scheele or Kirwan. In contrast, both Boyle and the

Lavoisians underscored, in different ways, the underlying homogeneity of the material realm, which in turn paved the way for their respective physicalist reductive enterprises.

A post-Sceptical Chymist chymical practitioner, Duclos challenged Boyle on the latter’s own grounds. While Boyle preached for a thoroughly empirical and experimental chemistry, Duclos exposed Boyle’s shortcomings as a practitioner, demonstrating and

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explaining to his fellow academicians how and why Boyle failed. Duclos solved with ease chymical matters that Boyle had presented as enigmas, exposing Boyle for lack of both literary and experimental proficiency. In response to Boyle’s chymical corpuscular explanations585—commonly based on a structural reduction of matter to material parcels

(endowed with spatial extension) in motion—Duclos did two things. First, he presented a radically different definition of matter. Fontenelle picked up some its essence in presenting, pejoratively, the “chemically-minded” Duclos as employing a chymical epistemology based on “gross and palpable principles such as salts, sulfurs, etc.”

Expressing his discontent with such chymical explanations, Fontenelle alluded to the

Paracelsian Tria Prima (salt, sulfur and mercury), thus associating Duclos with occultism,

Platonism and natural magic. At the same time, Fontenelle’s allusion to “palpable principles” hinted, incidentally, at a much more significant dimension of Duclos’s SER: his redefinition of chymical corporeality, for “corporeal, [was] not that which is extended in three dimensions geometrically; but that which is palpable” while “incorporeal, and spiritual [was] that which in this sense is not corporeal, and cannot be handled or touched sensibly.” Secondly, in accord with this redefinition, which drew a new line between chymical epistemology and its subject matter, Duclos rejected Boyle’s (extensive) recourse to the size, configuration and texture of corpuscles, deeming these as imaginary and speculative.

585 Whether these corpuscles were considered as utterly ‘physical’ and homogenous or as endowed with some type of secondary, hence chymical, qualities. By ‘secondary’ qualities I mean properties that may be ascribed to particular substances as opposed to universal matter. See Clericuzio (1990), pp. 579-583.

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In Duclos and Boyle we also see two different approaches to how chymistry should be modernized, for both chymists saw the need for a reform. But Boyle’s reform was a reductive one—to establish a “philosophical chemistry”—whereas Duclos’s reform consisted of a redefinition of traditional chemical philosophy, paying particular attention to elemental theories, which were one of Boyle’s major targets. For Duclos, neither the

Paracelsian Tria Prima nor the peripatetic four elements (or their combinations) were the true elementary constituents of bodies or mixts. Yet instead of rejecting them in entirety,

Duclos suggested their inclusion within a distinct context. On this account, the peripatetic and Paracelsian principles were allowed a heuristic role, tightly linked to a certain type of chymical analysis: distillation, or fire analysis. As a physical, hence partial, means of analysis, traditional elements could be identified with distillatory fractions, for instance.

This superficial kind of decomposition, which could not yield the ultimate constituents of mixts was pitted against solution analytical chymistry, in which one of the three components of the Tria Prima—salt—was accorded a special status; Duclos linked it to

Paracelsus’s sel circulé and especially to Van Helmont’s alkahest as an agent that could occasion a radical, chymical resolution, as opposed to a superficial and physical one. One significant distinction—within the context of Duclos’s SER as it pertained to his operative epistemology—between these two types of resolution lied in the principle of reversibility.

To wit, the chymical, deep-level, vegetal and fermentative solution decomposed mixts into their ultimate constituents in such a way that the initial mixt could not be recovered; the chymical process was therefore considered transformative or transmutational. In contrast, the physical, superficial, mechanical decomposition was akin to the separation of parts of an aggregate (as Bergman would later refer to physically-combined masses of matter); in

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this case, the resolved body or mixt did not undergo transformative changes and hence it could be recovered from its corresponding constituents.

Writing in the post-Newtonian era, when the concept of affinity assumed a central role, Lewis distinguished between two types of attraction or combination, which entailed analytical differences analogous to the ones pointed out by Duclos. “The mechanical attraction,” Lewis noted,

obtains between bodies considered each as one whole… the comparative forces, with which they tend together at different distances, are objects of calculation. When the attracting bodies have come into the closest contact we can conceive, they still continue [as] two distinct bodies, cohering only superficially, and [are] separable by a determinate mechanic force.586

“The chemical attraction, or affinity,” on the other hand,

obtains between bodies as being composed of parts, and as being of a different species of matter from one another… [when the bodies] are brought into the closest contact, there is frequently necessary some other power, as fire, to excite their action upon one another. In proportion as this action happens, they are no longer two bodies, but one… the properties of this new compound are not in any kind of ratio of those of the compounding bodies, nor discoverable by any mathematical investigation… as the chemical union, and the properties thence resulting, are exempt from all known mechanism, so neither can the bodies be separated again by mechanic force.587

In the debate over the causes of coagulation, Duclos argued that “the fluidity acquired by metals in acids… may well follow from the discontinuation of the particles of their bodies, which cannot be… radically resolved.” Lewis reasoned in an analogous way concerning

“mechanical attraction,” in which case, he held, the constituents parts of a body “still

586 Lewis (1763-65), p. iv. 587 Lewis (1763-65), p. v.

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continue [as] two distinct bodies, cohering only superficially, and [are] separable by a determinate mechanic force.” Similarly, Newton mentioned the “mechanicall coalitions or seperations of particles as may appear in that they returne into their former natures if reconjoined or… dissevered, & that without any vegetation.” Yet when, for example, a gentle and prolonged heat was applied to milk, occasioning a fermentative process by which milk was transformed into cheese and whey (serum), the process in question was a distinctly chymical-vegetal one, for no “mechanic force” could reproduce the milk; in much the same way, Duclos claimed that “the fluidity of bodies radically and totally resolved… must proceed from some other cause than the discontinuation of the reduced particles, since these liquors are irreducible [irreversible].” Duclos’s “other cause” is akin to Lewis’s “laws of another order,” and is consonant with Newton’s opinion that, “so far as by vegetation such changes are wrought as cannot be done without it, we must have recourse to some further cause. And this difference is vast & fundamental because nothing could ever yet be made without vegetation which nature useth to produce by it.” Such is the magnitude and significance of the exclusivity of the chymical realm.

It seems that Lewis’s remarks were expressed solely against the backdrop of the seventeenth-century mechanical philosophy. Yet given the increasing awareness of the concept of mass and the corresponding significance of gravimetric practices, already prominent in the mid eighteenth-century (Joseph Black’s experiments with magnesia alba are a striking example), it is not surprising to find Lewis referring to Archimedes, who in a celebrated instance concluded, “that if gold and silver were mixed together, the quantity of each metal in the mixture might be found by calculation from the bulk of the mass compared with its weight; and on this foundation, he is said to have discovered a

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fraudulent addition of silver made by the workman in Hieros golden crown.” Lewis then proceeded to situate the “mechanical philosophy” in a modified context, expressing concerns that were also articulated in the Chemical Revolution of the 1780s. “The mechanical philosophy”, Lewis noted, has extended Archimedes’s

way of investigation to many different mixtures, and computed tables for facilitating the operation; not aware, that though the method is demonstrably just if the two bodies were joined only superficially, the case is otherwise when they are intimately combined together. The act of combination, whether in bodies brought into fusion by fire, or in such as are naturally fluid, is truly chemical, and the laws of mechanical philosophy have no place in it.588

Finally, he remarked:

it is obvious that in all these [truly chemical] cases, the action is not between bodies considered as aggregates or masses, but between the insensible and dissimilar parts of which they are composed; that the several effects can be regarded no otherwise than as simple facts, not reducible to any known mechanism, not investigable from any principles, and each discoverable by observation only; and that the powers, on which they depend, are, so far as can be judged, in the present state of knowledge, of a different kind of those, by which bodies tend to approach or cohere with forces proportionate to their distances, or to resist or propel according to their quantities of matter and velocities. It seems of importance, that these two orders of the affections of bodies be kept distinct, as many errors have arisen from applying to one such laws as obtain only in the other.589

Lewis’s extension of the meaning of “mechanical” to include mass is instructive. Clearly,

Lavoisier’s concern with the principle of weight conservation arose from the increasing dominance of the concept of mass, which in chemistry, the realm of micro-matter, became identified with “bodies [that were] considered as aggregates.” When Lewis wrote these

588 Lewis (1763-65), p. ix. 589 Lewis (1763-65), pp. viii-ix.

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words, Lavoisier was at most 22 years old. Chemistry had to wait for another decade before Lavoisier announced his momentous contributions and Priestley became fully engaged in chemical pneumatic research. Interestingly, Lewis’s concerns were similar to those expressed by Priestley and Kirwan twenty years later. Lewis was also warning chemists in ways that would later be leveled against the Lavoisians. Lavoisier sought to deduce all chemical knowledge from a strict set of experimental “principles,” while Lewis warned, as did other phlogistonists later, that chemical knowledge is comprised of a wide set of material and experimental phenomena, “not reducible to any known mechanism, not investigable from any principles, and each discoverable by observation only.” By “simple facts” Lewis alluded to the particularity of the chemical realm. Over two decades later, the Lavoisians will establish their authoritative version of “absolute facts,” as derived from carefully quantified experimental setups. Lewis, like Priestley or Nicholson in their turn, argued against reduction in espousing a chemical SER based on “observation only.” The

Lavoisians, as we have seen, upheld a strict regime of experimental “observation” too, but it was mainly the gain and loss of weight (and heat) that they so systematically observed; their gravimetric practices were equally applicable in bodies considered as “aggregates or masses” of homogeneous matter. Of course, Lavoisier was also a chemist who was concerned with the chemical qualities of matter; but his SER was regulated by gravimetry.

All types of SERs in early modern chemistry that we have seen share a common message: while quantificational procedures are essential to chemical practice, the science of chemistry eludes quantitative physicalist reduction; hence the importance of understanding the complex interrelationship between quantification and chemistry. Time and again, as we have seen, chemists resisted the attempts at reductive quantifications of

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their science, demonstrating, in various ways, that the “truly chemical” abides by “laws of another order.” Scientific systematic quantifications are epistemologically compelling but these are but “false shew[s] of simplicity”, and this kind of chemical “simplicity,” Kirwan warned, “though seducing in some cases, becomes insufficiency in many other.”

Whenever considered from an explicitly quantitative standpoint, its explanation and elaboration require the recourse to what Newton described as “some further cause”. It is true that a complete understanding of “truly chemical” causality, as seen in early modern chemical SERs, was out of reach, but that did not mean that the chemist was denied that lofty status accorded to natural philosophers: the supposed knowledge of causes. Early modern chemical SERs show us repeatedly that they comprise much more than natural histories of chemical phenomena. Priestley, in line with Duclos’s SER, proclaimed that in chemistry, the potential of “observation[s]” notwithstanding, “mere observation and reflection will not carry a man far.” The basic units the chemist works with are not

“masses” or “aggregates” or corpuscles, but rather, as Fontenelle observed, they are “gross and palpable principles.” Fontenelle’s “principles” were Priestley’s chemical

“substances,” which the chemist would “frequently have occasion… to put… into various new situations.” With the chemists’ “much expence, as well as labour,” the science of chemistry would gradually attain the ideal not of “simplicity” but of “uniform[ity].”

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