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Chem. Listy 96, 997 ñ 1005 (2002) Refer·ty

VITRIOL IN THE HISTORY OF

VLADIMÕR KARPENKOa and JOHN A. NORRISb , and wood) and India (earth, , , , and space)1. Western appears to have arisen in Hellenistic Egypt aDepartment of Physical and Macromolecular Chemistry and and the Near East during the last couple of centuries BC, in bDepartment of Philosophy and History of Natural Sciences, conjunction with several mystical sects and the increasingly Faculty of Science, Charles University, Albertov 6, 128 43 common craft practices of creating imitation precious stones Prague 2 and metals2. Although it lacked the logical rigor of earlier e-mail: [email protected] Greek philosophies, alchemy nonetheless attempted to engage the complex world of chemical processes and sub- Received 20.XII.2001 stances in a scientific way, which eventually led to ideas involving the transmutation of into precious ones and the preparation of a substance for extending the human Keywords: alchemy, mineralogy, , , nitric , life-span. The term protochemistry is often used to refer to , ar-R·zÌ, Pseudo-Geberian corpus some of these activities, and it is this aspect of alchemical activity with which the present work is concerned. Many chemical and mineral substances known to the ancients were of great importance to civilization. The most Contents ancient literary evidence of familiarity with such substances is from Sumero-Assyrian dictionaries that include some 1. Introduction chemical terms. By the time of the rule of the Assyrian king 2. in Antiquity Assurbanipal (668ñ626 BC), these lists of chemical terms 3. Vitriol in Alchemy included several kinds of common (NaCl), 4. Vitriol in Indian Alchemy (CaSO4 . 2 H2O), and substances recognized today as metallic 5. Vitriol in European Alchemy and Mineral Industry sulfates and sulfides3,4. In ancient Egypt an impure form of 6. Vitriol and the Mineral was particularly important in mummifica- 6.1. tion. The discovery of gunpowder in China around the ninth 6.2. Sulfuric Acid century AD led to an increased interest in saltpeter (KNO3). 7. Conclusions Other substances were recognized to have remarkable physi- cal properties, such as the easily sublimated sal ammoniac (NH4Cl). The extraction of from 1. Introduction (HgS) seems to have become common practice by the end of the fourth century BC. The earliest extant description of this Although chemistry is widely considered among its practi- process is in the treatise On Stones by Theophrastus5 (c. 372 ñ tioners to be a modern science, technological processes based c. 287 BC), while the synthesis of cinnabar by on chemical reactions have been in standard use from the combining and then subliming mercury and seems to distant past. The production of , and paints, cosme- have been known6 before AD 400. A group of mineral sub- tics, and fermented beverages made use of techniques and re- stances that probably attracted attention due to their often actions common to chemical experimentation (such as filtra- striking blue and and their distinctive chemical tion, dissolution, and sublimation). Among these early crafts, properties were the sulfates of divalent metals (principally of metallurgy involved a widening knowledge of metals and their and ), commonly known in early terminology as alloys, and entailed the recognition of certain stones as metal- atrament and vitriol (the latter of which will be used in this lic ores. However, these activities seem to represent only paper). In this paper we will attempt to trace the history of a practical, applied use of chemical processes. Although craft- vitriol as revealed in chemical literature from antiquity to the -workers may have developed their own concepts regarding , and discuss some examples of its uses the substances involved in a given process, records of such and opinions about its nature and effects. ideas have not come down to us, and the discoveries and The mineral substances referred to here as vitriol are improvements they made seem to have been based largely on recognized in modern science as hydrated sulfates of iron, a trial-and-error approach. copper, and even and , all of which form as The ancient considerations on the nature of matter that secondary within the zones of metallic have come down to us were composed by philosophers who deposits. These were generally referred to as considered the problem of change. In attempting to understand ìpyritesî during antiquity. Use of this term became more the objects of the natural world and the changes these objects restricted by the sixteenth century to refer mostly to sulfides undergo, the idea of earth, air, fire, and water as material of metallic luster which yield little or no metal, although more elements was first postulated by the Greek natural philosopher minerals than the one currently called were still included Empedocles (492ñ432 BC), and was brought into its most well under this term. The name marcasite was used by the in known form by (384ñ322 BC). Analogous referring to these same minerals, and became used synony- appeared around the same time in China (fire, earth, water, mously with in much of the literature of the sixteenth

997 Chem. Listy 96, 997 ñ 1005 (2002) Refer·ty century Europe. It was probably during the course of mining vium) and its subsequent coagulation in open trenches or vats. such sulfides that vitriol became noticed. The iron and copper Both Dioscorides and Pliny designate these vitriolous mate- varieties of vitriol were widely recognized and utilized in rials by the terms chalcitis, melanteria, misy and sory.Al- antiquity, and were commonly referred to respectively as though both authors attempt to describe each of these vitrio- green and blue vitriol. In modern mineralogical terminology7, lous earths in detail, it seems doubtful that they had personal the green and blue vitriol correspond to melanterite (FeSO4 . experience with them. Moreover, as these materials were 7 H2O) and (CuSO4 .5H2O), respectively. The mixtures of sulfides, sulfates, and clays in varying de- blue and green varieties were known to form spectacular cry- grees of chemical and physical condition, and containing stals of a vitreous luster, although their formation in botryoi- varying degrees of enrichment, it is doubtful whether dal, granular, or stalactitic masses is more common. In these these names could havebeen used in a strictlyuniform senseeven latter forms, these sulfates often appear in dull shades, and the among the vitriol manufacturers themselves. Nonetheless, we iron sulfate often appears in shades of blue, yellow, or even must note the significance of such subdivision among these completely white. These sulfates are highly soluble and prone substances, for it further demonstrates that vitriol was consid- to degradation by absorbing water. As such, their occurrence ered to comprise a group of related substances, among which is ephemeral, and the vitriol of commerce was that extracted workers attempted to make qualitative distinctions. from the earthy masses and of decomposing sulfide So far, this discussion has shown that already from the and sulfate minerals. beginning of the current era, vitriol was characterized as being compositionally related to copper, forming from a , and as representing a specific mineral group. Vitriol and its 2. Vitriol in Antiquity related substances continued to be commonly used throughout later antiquity. Dioscoridesí medical interest in these substan- The antiquity of familiarity with vitriol is shown by a Su- ces was followed up by the Graeco-Roman physician merian word list dating from around 600 BC, in which types (c. AD 129 ñ c. 200), who discusses these vitriol substances of vitriol are listed according to color8. However, the earliest in Book 9 of his tract On Medical Simples14. These substances surviving discussions of vitriol in the literature of antiquity are also found their way into various metallurgical processes, the works of the Greek physician Dioscorides (first century being used in the purification of and in the fabrication of AD) and the Roman naturalist Pliny the Elder9,10 (AD 23ñ79). imitation precious metals. The routine empirical use of these Referring mainly to the vitriol produced in the vicinity of the substances in such operations are recorded in the Physica et copper ore deposits on Cyprus, both authors describe vitriol mystica of Bolos-Democritus15 (c. 300 BC), the third century forming as white dripstones in caves, mine tunnels, and along AD writings of Zosimos16, and in the roughly contempora- 17 the sides of pits dug into the aforementioned ëvitriolousí neous Leyden Papyrus X, all of which reflect vitriolís invol- earths. They also mention artificial vitriol obtained from the vement in the early development of alchemy in Hellenistic congelation of both naturally occurring and artificially prepa- Egypt. red solutions of these sulfates. In all cases, the origin of vitriol from a liquid, or a solution as we would say (Pliny called it a limus), was definitely recognized. 3. Vitriol in Arabic Alchemy Dioscorides indicates that vitriol was considered as a mi- neral genus encompassing a number of varieties that he desig- An early attempt to systemize the classification of mineral nates by mode of origin. We can thus see that vitriol had substances beyond the level of metals, stones, and earths is that already attracted enough attention by workers in the mineral of the Persian physician and alchemist Muhammad ibn Zakka- industries to be considered unique among minerals and to be rÌja ar-R·zÌ (c. AD 854ñ925/935). In his Book of Secrets recognized by its chemical qualities despite its various mani- (Kit·b al-asr·r), written around 900, he classified all substan- festations. Perhaps because of its usual association with sulfide ces known to him, first dividing them into four main groups: ores that were mined mainly for copper, vitriol was commonly mineral (Table I, as given by Newman18), vegetable, animal, thought to be a cupriferous substance. By virtue of this suppo- and derivatives of these. The latter included substances that sedly cupriferous nature, the Greeks called vitriol by the name ar-R·zÌ was unable to include into any of the three preceding chalcanthon, while in Latin it was called atramentum sutorium groups, as for example litharge (basic carbonate), verdi- with reference to its principal commercial use as a blackening gris (basic copper ), and tutia (zinc ). agent for leather. However, as this property of blackening Among ar-R·zÌís table of mineral categories vitriol ap- leather can only be accomplished by the iron-rich vitriol, and pears as a class of six substances. This grouping testifies to the in consideration of the composition of the sulfide deposits on continued recognition of the qualitative and chemical relations 11 Cyprus , it is probable that most of the vitriol used in antiquity among vitriol and its related substances despite their various was actually iron-rich in spite of its association with copper appearances and chemical effects. He included among ores (the presence of iron in these substances appears to have the types of vitriol, probably due to the similarities in their remained unrecognized until the sixteenth century). adstringent qualities and mode of occurrence; for although As mentioned above, commercial vitriol was obtained alum had industrial and medical uses different from those of 12 through lixivation techniques that probably originated with vitriol, both were manufactured by similar means and someti- similar processes for obtaining alum in ancient Mesopota- mes even occurred together. Otherwise, the remaining five 13 mia . These processes entailed the dissolution of vitriolous types of vitriol in ar-R·zÌís group seem to be various deriva- material or the collection of naturally occurring vitriol solu- tives of the copper and iron sulfates, distinguished roughly by tions, followed by the of the solution (or lixi- color, most of which he referred to by Arabic transliterations

998 Chem. Listy 96, 997 ñ 1005 (2002) Refer·ty

Table I Table I ñ continued R·zÌís classification of minerals in an abridged latinized form; in some cases one substance is classified as more types in the iron vitriol < i.e. iron sulfate >, thus iron oxide original version. The difference was often only in purity of on the otherî] such a substance, but sometimes they are quite different com- 6. Surianum or red atrament [= Arab. s˙rÌ or s˙rÌn: pounds. same as calcatar] E. Six Boraces [= Arab. bauraq (i.e. Na B O ); 7 types, Terrena (ìEarthy thingsî) 2 4 7 in this group also Na2CO3 and K2CO3 were included] A. Four Spirits [volatile substances] F. Eleven Salts 1. Quicksilver 1. Common salt [presumably NaCl] 2. Sal ammoniac (NH4Cl) (three types) 2. Bitter salt [perhaps a type of rock-salt] 3. Auripigment (six types distinguished by their 3. Salt of calx [slaked lime; Ca(OH)2] color; this group includes both As2S3 and As4S4) 4. Pure salt [pressumably NaCl] 4. Sulfur (five types, including black one which was 5. Sal gemma [rock-salt; NaCl] either sulfur mixed with asphalt or iron sulfides) 6. Salt of naphta [presumably NaCl contaminated B. Seven Bodies [i.e. seven known metals] with asphalt] Gold, , copper, , iron, lead, and ìKaresinî 7. Indian salt [not identifiable] or ìCatesinî [the Arabic kh·r sÌnÌ, ìChinese ironî, 8. Salt effini [= Lat. essini < Arab. as-sÌnÌ: Chinese possibly a bronze composed of copper, zinc, and salt. Not identifiable] ] 9. Sal [= Arab. al-Qali: soda] C. Thirteen Stones 10. Salt of urine [NaNH4HPO4, produced by 1. Marchasita [= Arab. marquashÌt·: the minerals decomposition and drying of urine] now known as ìpyritesî, including ìfoolís goldî 11. Salt of cinder [; K2CO3] (FeS2). Four types mentioned by ar-R·zÌ cannot be positively identified] 2. Magnesia [= Arab. maghnÌsiy·: an old alchemical ìcover-nameî used to denote various substances; of the Greek names chalcanthon, chalchitis, colcothar, and three types] sory. 3. Edaus (or daus) [= Arab. daus: either an The fact that ar-R·zÌ designated vitriol as a special group composed of iron oxide, or iron fillings, or even speaks for the interest in and importance of these materials in iron slag] the of as skilled a chemist as he undoubtedly was. As 4. Thutia [= Arab. tutÌy·: usually zinc carbonate a physician his activity in alchemy was of a practical nature, and oxide] and he declined from speculating on the mineralogical origins 19 5. Azur [= Arab. l·zward: lapis lazuli] of the substances he used. As Multhauf has pointed out, one 6. Dehenegi [= Arab. dahnaj: ; of ar-R·zÌís most significant contributions to chemistry was this systemization of mineral substances. Ar-R·zÌís categori- CuCO3.Cu(OH)2] 7. Ferruzegi [= Arab. fÌr˙zaj: turqouise] zation of the vitriolous substances among the other types of 8. Emathita (elsewhere sedina or sedena) [= Arab. minerals was an important step in codifying the recognition of sh·danaj: hematite or bloodstone] the compositional similarities and relations between these 9. Cuchul [= Arab. kuhl: sulfide and lead substances, while his mineral system was so apt that it remai- sulfide (galena), often confused]. ned in use for several subsequent centuries. 10. Spehen [apparently a misreading of Isfahan] The importance of ar-R·zÌís consideration of vitriol comes 11. Funcu [= Lat. succen < Arab. ash-shukk, arsenic into sharper focus when compared with those of other Arabic 20 oxide] authors . For instance, in his Great Book of 12. Talca [= Arab. talq: not our ìtalcî, but mica Properties (Kit·b al-hawass al-kabir). He is a mysterious or layered gypsum] figure in alchemy; doubt still persists as to whether there was ever an actual person of this name. The supposed dates of his 13. Gipsa [= Arab. jibsÌn: gypsum; CaSO4] D. Six Atraments [the class of ìatramentsî contained life are AD 710/30 ñ c. 810. A detailed discussion of this 21 metallic sulfates and their impurities] problem is given by Haq . Jabir divided all mineral substances into three groups: spirits (substances that completely evapora- 1. Black atrament [impure FeSO4] 2. Alum [a rather vague category including te when heated), metallic bodies (metals), and mineral bodies. This third group contained malleable mineral bodies that either KAl(SO4)2 in varying degrees of purity as well as other metallic sulfates] melt or remain unchanged in fire. This author included vitriol 3. Calcandis or white atrament [= Arab. qalqant: in a subcategory of the mineral group for substances that weathering product of copper/iron ores or alum] contain only a very small proportion of ìspiritî (the separable, 4. Calcande or green atrament [= Arab. qalq·dis: volatile part), and which also included shells, pearls, and iron and/or copper sulfate] ìflower of copperî (qualquant). Another author, Muhammad 5. Calcatar or yellow atrament [= Arab. qalqat·r: ibn Ibrahim al-Watwat (1234ñ1318) divided mineral substan- ìdecomposition product of sulfide- and sulfate ces into seven groups in his treatise Mountains and Minerals rich copper/iron ores on the one hand, and burnt (Mabahig al-fihar). Vitriol appears in the group called ìstones whose nature changes that of other stonesî, along with ,

999 Chem. Listy 96, 997 ñ 1005 (2002) Refer·ty magnesia, and potash. Although this categorization does not vitriol as a distinct group of mineral substances. These mate- seem to entail the degree of chemical understanding implied rials continued to acquire extraordinary importance in both in ar-R·zÌís system, it nonetheless betrays a certain metallur- practice and . As will be discussed below, further at- gical rationality in that all of the aforementioned substances tempts to explain the nature of vitriol on a chemical basis were used in the purification and coloring of metals. Such appeared in Europe during the sixteenth century, when alche- categorization could also suggest that this author was familiar mists and other workers in the mineral industries sometimes with the reaction in which iron immersed in a vitriol recorded their knowledge and ideas about these strange sub- solution seems to change into copper (this reaction is further stances. discussed below). Lastly, the Arabic author Abdallah ibn SÌn· (commonly known as , 980ñ1037) divided minerals into stones, sulfurs, salts, and metals in his Book of Remedy 4. Vitriol in Indian Alchemy (Kit·b aö-öif·). He included vitriol and its related substances in the category of salts, as he considered them to be composed The alchemy that developed in India contains features that of saltiness, sulfurness, and stoniness. are characteristic of the philosophical and religious back- Ar-R·zÌís influence in the recognition of various types of ground of that region. As such, Indian alchemy was more vitriol appears in the work of an anonymous eleventh century focused on a practical approach to human health, and to this Spanish Arab known to modern scholarship as Pseudorhazes end it widely utilized substances made from plants and inor- (because the thirteenth century Latin copies of this work were ganic compounds. The interpretation of such recipes is often attributed to ar-R·zÌ). This book, known in its Latin version as problematic, as is dating many of the works and identifying De aluminibus et salibus (On and Salts), contains their authors23. a chapter about vitriol, which begins as follows22: ìKnow that Mention of vitriol in Indian alchemy does appear in some there are many kinds of vitriol, and their places of occurrence late medieval writings24, but often only the blue or green are numerous. These vitriols are water and color that have varieties are included. For example, inorganic substances are coagulated by the dryness of earth, and there is something hot classified in part IX of the Rasahridaya attributed to Bhikshu and dry in their nature. And one of their kinds is Colcothar Govinda (c. eleventh century AD). The most important of and [further kinds are] Sory and Calcythis and Calaminaris these groups in Indian alchemy was the rasas. This word [?] Ö And these vitriols blacken [metallic] bodies and give to originally meant ìjuiceî, was later used to refer to mercury, the red [body] yet more redness and blacken the white; and and in the present sense seems to indicate a group of minerals the finest of it is Colcothar and the coarsest is Sory.î whose origin or composition were supposed to have involved Although this description of vitriol is brief, it contains a liquid component. This group includes blue vitriol (sasyaka), significant information on how vitriol was characterized on pyrites, cinnabar, calamine, and an unidentifiable variety of a qualitative level. The moist yet earthy nature of the vitriolous iron. There is no mention of any perceived similarities between earths, and their often striking colors, are addressed with these substances, nor is there any mention of green vitriol. The reference to their coagulative mode of origin, while the ìsome- twelfth century Rasarnava lists a group of eight maharasas thing hot and dry in their natureî refers to the sulfurous (or ìgreatî rasas) similar to that of the previously mentioned character of these substances. The inclusion of calaminaris work, and in which green vitriol is likewise absent. among these vitriolous earths is strange, as it is probably Conversely, both blue and green vitriol are mentioned in a reference to a hydrated oxide of zinc often associated with a Rasakalpa (a part of Rudraymala Tantra) written around AD the weathering zones around silver mines. If so, this author 1300. Yet blue vitriol is classified among maharasas, while must have included it due to its earthy nature and its ìcoagu- green vitriol is included among the rasas in this work. Both lativeî mode of occurrence, similar to that of the vitriolous substances appear again in this Rasakalpa, but this time as substances. a special group: kasisa (vitriol), pushpa kasisa (another vitrio- The following example of the laboratory treatment of lous substance; pushpa meaning ìflowerî), and hirakasisa vitriol is given in the subsequent paragraph of De aluminibus. (green vitriol; hira means ìprecious stoneî, and was perhaps Although this recipe appears to be somewhat corrupt, and used with reference to green vitriol by virtue of this mineralís although we cannot be sure of the intended result, it neverthe- striking green color and crystalline appearance). less reflects a chemical procedure: ìÖ thou takest as much as We can only speculate as to why more importance was thou willst of [vitriol]; and put [it] into a vessel, and let it stand ascribed to blue rather than green vitriol in Indian literature, one night in a hot furnace. Thereafter vitriol gets out red, of as both materials seem to have been generally known. Perhaps very strong redness. And then let it remain covered by a four- this was partly because the blue and green varieties have quite fold amount of pure sweet water, and let it stand until it distinct chemical effects. A possible explanation is that fami- dissolves, and it settles down as a sediment on the bottom. Then liarity with the in which solutions of blue let it trickle off [distillatio per filtrum], and return it [sediment] vitriol deposit copper onto solid iron surfaces caused the blue for future use.î Here, it seems that an iron-rich vitriol was vitriol to be considered as a special substance, while the strongly heated, with the resulting slightly soluble, red iron iron-rich green vitriol undergoes no such spectacular reaction. oxide being rinsed with water. This reaction was described in the Dhatuvada, dated around Although we have said almost nothing about the industrial the eighth or ninth century AD. This possibility gains further and medical uses to which vitriol was applied, we have attemp- support from a passage in the Rudrayamala Tantra showing ted to show by the above examples that the origin and chemical further recognition of the relation between blue vitriol and nature of vitriol did engage the thought of early workers in the copper, which reads: ìCopper in combination with the ëbur- chemical field. Thus far, this attention culminated in regarding ning waterí gives rise to blue vitriol.î Although a discussion

1000 Chem. Listy 96, 997 ñ 1005 (2002) Refer·ty of mineral acids in Indian alchemy is beyond the scope of this by the sixteenth century39. This addition would cause most of paper, the latter example makes it clear that in using copper to the copper present in the solution to precipitate onto the surface create blue vitriol, the Indian alchemists understood that blue of the solid iron, leaving an iron-rich vitriol solution and the vitriol must in some way contain copper. It thus seems possible solid iron coated with copper. Although this practice appears that these two types of vitriol were categorically separated in the lixivation processes described by Biringuccio and Ag- in Indian alchemy by virtue of their distinct chemical effects ricola, neither of them remark on its supposed purpose or and some degree of compositional knowledge of the blue significance. Ercker mentions the reaction itself, which he variety. believed to be a vitriol-induced metallic transmutation of iron into copper40. Ercker was not alone in this opinion, and it is to this aspect of the history of vitriol that we must now turn our 5. Vitriol in European Alchemy attention41. and Mineral Industry The use of solid iron to collect copper from solutions containing copper sulfate was used in the hydrometallurgical It was through works such as De aluminibus that vitriol production of copper in ancient China, when copper ore depo- entered the sphere of Latin alchemy. Here we find vitriol sits became too depleted to yield enough metal for coinage42. included in such disparate sources as an recipe in the This process was also used by the Spanish Arabs during the twelfth century On Divers Arts25, in the laboratory-oriented, Middle Ages, who appear to have discovered it independently gold-making recipes of the late thirteenth century Liber clari- when their copper deposits were also becoming exhausted tas26, and in widespread use in the growing corpus of Latin while iron remained abundant43. In the chemical literature of chemical literature. As will be discussed below, it is from the the sixteenth century, we find that this reaction was cited in use of vitriol by the Latin alchemists that sulfuric and nitric support of the possibility of metallic transmutation. Although acids were discovered. Changes also occurred in vitriol no- (1493/4ñ1541) never claimed to have transmuted menclature during this period. Among the earliest works to use metals other than by this single reaction, it nonetheless enabled the word vitriol (as opposed to atrament) are the eighth century him to extrapolate the possibility of further metallic transmu- Latin version of the Compositiones ad tingenda27, and the tations44. Paracelsus mentions this vitriol-induced reaction in 28 45 thirteenth century Book of Minerals of chapter XV of the Economy of Minerals , and in chapter VI of (c. 1200ñ1280). The name vitriol comes from vitrum, the Latin The Book Concerning the of the Philosophers46. word for glass, and was coined with reference to its vitreous In The Tincture vitriol is not mentioned by name47, but is luster. When the names vitriol and atrament remained in use called a ìlixivium of marcasitesî (as mentioned above, mar- during the later Middle Ages, vitriol seems to have been used casite was a term generally synonymous with pyrites). Two with reference to the vitreous, processed substance29. Coppe- locations cited by Paracelsus at which this vitriol solution ras was sometimes used to distinguish naturally occurring occurs naturally are the old Czech mining town of Kutn· Hora, vitriol from the refined variety30, although the names vitriol, and a fountain he designates as the Zifferbrunnen in Hungary. atrament, and copperas became used interchangeably by the At both of these places, the vitriol solution generated from sixteenth century31,32. Even as late as the publication of De marcasites was observed to transmute iron into high-quality natura fossilium in 1546, Agricola, who used the term atra- copper. In a brief discussion of vitriol in the Economy of mentum, notes that the name vitriol was becoming commonly Minerals, Paracelsus48 again mentions ìa fountain in Hun- used at the time33. gary, or rather a torrent, which derives its origin from Vitriol, Accounts of vitriol production processes appear in the nay, its whole substance is Vitriol, and any iron thrown into it literature of the sixteenth century mineral industry. In The is at once consumed and turned to , while this rust is Pirotechnia34 (1540) and De re metallica35 (1556), the authors immediately reduced to the best and most permanent copper, describe vitriol manufacturing techniques very similar to those by means of fire and bellowsî. mentioned by Dioscorides and Pliny (discussed above). One The preceding discussion has shown that although vitriol notable innovation is found in De re metallica36, in which was a substance of considerable interest within the spheres of Georgius Agricola (1494ñ1555) describes a process that goes the mineral industry and alchemy, understanding its composi- beyond the use of naturally occurring vitriolous earths and tion and chemical effects were important problems in the solutions by generating these directly from pyrites. This is the development of mineral chemistry. It was through the indus- earliest record of the recognition of the genetic relationship trial exploitation of vitriol and through further investigations between vitriol and the metallic sulfides from which they are of its mysterious properties that its composition and generation generated, and this innovation seems to have entailed an became increasingly understood. Unfortunately, space does increased understanding of vitriol and pyrites on the compo- not permit a discussion of the significance of these explora- sitional level. Lazarus Ercker (1528/30ñ1594) was an assayer tions in the further development of mineral chemistry, al- and metallurgist who lived in Bohemia from 1567; the empe- though it should be mentioned that it was mainly through the ror Rudolf II named him master of the Prague mint in 1583. work of Angelus Sala49,50 (?1576ñ1637), Nicolas Guibert51 In his Treatise on Ores and Assaying (1574) he displays a full (?1547ñ?1620), and Robert Boyle52 (1627ñ1691) that the understanding of the compositional links between these two compositional dissection of vitriol was taken beyond the level mineral substances, for he describes procedures for assaying reached by Ercker, and the supposed transmutation of iron to pyrites for vitriol37, and shows the earliest understanding of copper became understood as a reaction between copper the compositional complexity of both substances38. in the vitriol solution and the iron of the solid surface. Belief Interestingly, the addition of solid iron to the vitriol solu- in this reaction as a metallic transmutation nonetheless survi- tion during the lixivation process became standard procedure ved even in the eighteenth century53.

1001 Chem. Listy 96, 997 ñ 1005 (2002) Refer·ty

→ 6. Vitriol and the Mineral Acids 2 CuSO4 2 CuO + 2 SO2 + O2 → 6.1. Nitric acid KNO3 + SO2 KO3SONO → The discovery of nitric and sulfuric acid is often linked 2 KO3SONO N2O3 + K2SO4 +SO3 with the alchemist known as Geber. This name is the latinized form of Jabir, an Arabic alchemist mentioned above. The If the cooling is insufficient, N2O3 decomposes spontane- appearance of Latin works under the name Geber in the late ously: Middle Ages led to considerable confusion, as this author was → identified with the Arabian Jabir for quite a long time. Al- N2O3 NO + NO2 though modern historiography has shown that the Latin Geber, as he was later called, or Pseudo-Geber in modern literature, or otherwise reacts with water: was not the Arabian Jabir, the identity of the Latin author yet 54 → remained unknown. Newmanís recent investigations on this N2O3 +H2O 2 HNO2 subject have resulted in two important conclusions. First, the Summa perfectionis magisterii of the Latin Geber was proba- and the subsequent disproportionation of HNO2 produces HNO3: bly written around the end of the thirteenth century by the → otherwise unknown Franciscan monk, Paulus of Taranto. Se- 3 HNO2 HNO3 + 2 NO + H2O cond, other works that appeared in print under Geberís name in 1541 were not written by this same author, which is why we produced in the first reaction oxidizes NO: speak of a Pseudo-Geberian corpus. Among the other texts that → comprise this corpus is the De inventione veritatis, in which 2 NO + O2 2 NO2 the earliest known recipe for the preparation of nitric acid is found. As dating the works of the Pseudo-Geber corpus is and the dissolution of the resulting oxide in water yields further problematic, dating the discovery of nitric acid is likewise nitric acid: uncertain. It is estimated that this discovery took place after → 1300, some two hundred years before it appeared in print. 4 NO2 + 2 H2O + O2 4 HNO3 This recipe, titled About dissolving liquids and softening oils reads as follows55: ìTake a pound of Cyprus vitriol [Fe, Schrˆder59, who repeated Agricolaís experiment, arrived CuSO4], a pound and a half of saltpeter, and a quarter of at following result: the dry of 150 g KNO3, 150 g a pound of alum. Submit the whole to distillation, in order to CuSO4, and 50 g KAl(SO4)2 at 800 ∞C yielded 70 g of appro- withdraw a which has a high action. The dis- ximately 51 % (wt) HNO3 and 0.4 % HNO2. solving power of the acid is greatly augmented if it be mixed with some sal ammoniac, for then it will dissolve gold, silver, and sulfur.î The addition of sal ammoniac to the distillate 6.2. Sulfuric acid to (a mixture of HNO3 + HCl, in proportion 1:3). Nitric acid had become a commonly used substance by the The history of sulfuric acid is especially difficult to trace, mid-sixteenth century. Biringuccio56 describes its purification as no reliable recipe for its preparation is known prior to the by adding a small amount of silver, which has the effect of sixteenth century. Nevertheless, there are vague allusions to it removing the traces of HCl that originate from the KCl some- in the work of Vincent from Beauvais (d. 1264) and in the times present as an impurity in saltpeter. And although the Compositum de compositis ascribed to Albertus Magnus60.In term aqua fortis was already in regular use, Agricola57 interes- both cases, the description concerns the distillation of alum. tingly chose to refer to it as aqua valens in his De re metallica. A passage from the second part of Pseudo-Geberís Summa This latter work contains several recipes for this acid, not all perfectionis, as interpreted by Darmstaedter61, was long con- of which actually lead to nitric acid (some resulted in a mixture sidered to be the earliest known recipe for sulfuric acid (the of all three strong mineral acids). One of his recipes that does chapter in Summa is titled ìAbout the of the first yield nitric acid prescribes the following ingredients: ìfour order for the yellowing of silverî). In the recent translation by librae of vitriol, two and a half librae of saltpeter, half a libra Newman this passage reads62: ìLuna is also yellowed similarly of alum, and one and a half librae of spring water.î with a solution of . The method of that yellowing which Agricola also describes ìcertain compositions which pos- is perfected by vitriol or copperas is as follows. A specific ses singular powerî, one of which reads as follows: ìThe quantity of either of them should be taken, and the part of that second composition is made from one libra of each of the which allows itself to be sublimed should be sublimed until it following, artificial orpiment [As2S3], vitriol, lime [CaO], is sublimed with a total expression of fire. After this, what was alum, ash which the dyers of wool use [K2CO3 ?], one quarter sublimed should be sublimed again with a suitable fire, so that of a libra of verdigris [impure basic copper (II) acetate],and it be gradually fixed, until the greater part of it is fixed. Then one and a half unciae of stibium [Sb2S3].î This example is let it be calcined carefully with intension of the fire, so that revealing of the attempts that were made in Agricolaís time to a greater fire can be administered to it for its perfection. Then prepare even more potent . it should be dissolved into a red water to which there is no According to Soukup and Mayer58, Agricolaís correct equal.î In a footnote concerning this passage Newman states recipe for nitric acid can be expressed by the following set of that ìThis is not a recipe for sulfuric acid Ö Copper sulfa- consecutive reactions: te decomposes at 700 ∞C to cupric oxide; further heating to

1002 Chem. Listy 96, 997 ñ 1005 (2002) Refer·ty

1050 ∞C will produce cuprous oxide, a red compound often releases two moles of water at 30 ∞C, two further moles at 110 ∞C, used as a . The Summaís advice that this be sublimed and the rest at 250 ∞C. may be a thought-experiment. Alternatively, if the starting (c) Spiritus vitrioli:theSO2 that reacts with water in a receiver, product were iron sulfate, iron oxide would be produced by yielding H2SO3: simple decomposition of the sulfate to the oxide, again brought → by heating.î 6 FeSO4 Fe2(SO4)3 + 2 Fe2O3 + 3 SO2 In the interest of exploring this problem, it will be instruc- 63 → tive to compare this recipe with others. 2 CuSO4 2 CuO + 2 SO2 + O2 (c. 1556ñ1616) writes at length about spirit of vitriol (Vitriol- geist) in his book Alchemia (1597), in which he distinguishes The slow oxidation in air leads to sulfuric acid: a white kind and a red kind. In his opinion, the latter spirit is → pure ìoil of colcotharî, or a red liquor remaining after the 2 H2SO3 + O2 2 H2SO4 separation of a white spirit. As colcothar was usually Fe2O3 precipitated during the reaction, it seems probable that this is (d) At temperatures above 480 ∞C, ferric sulfate decomposes a description of the preparation of an acid contaminated by in a process known as Vitriolbrennen, a red oxide. Red colors likewise appear in similar recipes in → his text. Fe2(SO4)3 Fe2O3 + 3 SO3 Another comparable recipe appears in Basil Valentineís treatise Vom grossen Stein der alten Weisen dated around leaving behind the caput mortuum, which in this case is 1602. (The author of books published under this name was colcothar (Fe2O3). probably Johann Thˆlde (? ñ before 1624), the owner of When copper vitriol is used, it decomposes at very high a salt-works in Thuringia64). This recipe is cited from Schwarz temperatures, and Kauffman65: ìIf you get such a deeply graduated and well → prepared mineral, called Vitriol [FeSO4], Ö , put it into a well CuSO4 CuO + SO3 coated retort, drive it gently at first, then increase the fire, there comes in the form of a white spirit of vitriol [SO3] in the and in both cases SO3 reacts with water in receiver, producing manner of a horrid fume, or wind, and cometh into the receiver sulfuric acid. as long as it hath any material in it Ö if you separate and free Schrˆder67, who analyzed the production of sulfuric acid this expelled spirit well and purely per modum distillationis, in detail, distinguished between the spiritus vitrioli (or liquor from its earthy [H2O], then in the bottom of the glass vitrioli acidus primus) prepared in step (c) above, and the you will find the treasure, and fundamentals of all the Philo- vitrioli (liquor vitrioli acidus secundus) from step (d). sophers, and yet known to few, which is a red Oil, as ponderous According to this author, the latter substance is a thick, red- in weight, as ever any Lead, or Gold may be, as thick as blood, -brown, strongly smelling oily liquid comprised of approxi- of a burnt fiery quality.î mately 75 % H2SO4. This seems to be the substance that It is interesting to note the remark concerning the red oil Paracelsus referred to as oleum vitrioli rubrum, and it is in Valentineís description. Its apparent might lead us Schrˆderís opinion that this oil of vitriol was known as far to believe that it could have been a of red ferric back as the fourteenth century. oxide. Similarly, Paracelsus described the distillation of col- Schrˆder performed the of 200 g of vitrio- cothar that had already been used for the production of spiritus lum Goslariense (FeSO4 . 7 H2O), gradually elevating the tem- vitrioli, and the blood-red, oily liquid (oleum vitrioli) evolved perature to 1000 ∞C over a three hour period. As a result, he therefrom. obtained approximately 8ñ10 g of ìstrongly acidic liquid, In all three of the above-mentioned cases, an acid of a red smelling like SO2î. This liquid turned out to contain 2.9 % color was prepared. Valentineís mention of a sediment asso- SO2, and on standing it oxidized gradually to 2.75 % H2SO4. ciated with this liquid could support the suggestion that ferric With consideration of these facts, we now return to the oxide was present. Yet this oxide would have also contamina- problem of whether or not the above-mentioned process from ted the acid itself, giving it a red color. the Summa perfectionis of Pseudo-Geber resulted in the pro- The chemistry involved in this method of preparing sulfu- duction of sulfuric acid. It has been shown that a red liquid ric acid is described here according to Soukup and Mayer66,in obtained from vitriol is mentioned both in old and modern which the old terminology is used. The individual substances works. In these descriptions, both the process used and the involved in this process are as follows: color obtained correspond with those described in the Summa (a) Ros vitrioli (Dew of vitriol): the humidity of the salt used perfectionis. Although the language of this text is not entirely in this experiment. clear, it nonetheless seems possible that this process did lead (b) Phlegma vitrioli: structural water of the sulfate. to the preparation of sulfuric acid. The red color in question could have resulted from the presence of iron (III) compounds → FeSO4 .7H2O FeSO4 + 7 H2O that developed during the process and contaminated the pro- duct. However, as alchemists could not use chemicals of Six moles of water are freed at 115 ∞C, and the remaining analytical grade purity, the influence of unintentional impuri- one at a temperature above 280 ∞C. ties should also be considered. As Mellor68 has pointed out, The same process, this time using copper vitriol , when present as an impurity in sulfuric acid, imparts a red color to the product. As selenium can substitute for sulfur → CuSO4 . 5 H2O CuSO4 +5H2O in the mineral pyrite, it could also be present in natural or

1003 Chem. Listy 96, 997 ñ 1005 (2002) Refer·ty artificially prepared sulfates generated from such selenium- 2. Lindsay J.: The Origin of Alchemy in Graeco-Roman -bearing pyrite, and thus could have found its way into the Egypt. F. Muller, London 1970. acids prepared using these sulfates. Even though very little is 3. Levey M.: Ambix 6, 149 (1957). known about the provenance of the vitriol used by alchemists, 4. Campbell Thompson R.: Ambix 1, 3 (1937/38). the possibility of the presence of selenium as an impurity 5. Caley E. R., Richards J. C.: Theophrastus On Stones, should also be considered when attempting to ascertain whe- p. 58 and 203ñ205. Ohio State Univ., Ohio 1956. ther or not the process described by Pseudo-Geber was an early 6. Priesner C., in the book: Alchemie. Lexikon einer herme- preparation of sulfuric acid. tischen Wissenschaft (Priesner C., Figala K., eds.), p. 378. C. H. Beck, M¸nchen 1998. 7. Bernard J. H., Rost R. et al.: Encyklopedick˝ p¯ehled 7. Conclusions miner·l˘. Academia, Praha 1992. 8. Crosland M. P.: Historical Studies in the Language of The goal of this paper is to outline the historical importance Chemistry, p. 67. Heinemann, London 1962. of vitriol and to go some way toward illustrating its role in the 9. Agricola G.: De re metallica (Transl. Hoover H. C., and mineralogy. These salts, among Hoover L. H.), n. 11, p. 572. Dover Publ., New York 1950. which alum was sometimes included, were very important 10. Gunther R. T. (ed.): The Great Herbal of Dioscorides, substances in the dual spheres of theory and practice. The pp. 639ñ641. Hafner Publ., New York 1959. discovery of strong mineral acids, particularly of HNO3, and 11. Guibert J. M., Park Ch. F., Jr.: The Geology of Ore aqua regia, had a strong effect on existing ideas about mine- Deposits, pp. 391ñ395, 598ñ603, and 796ñ823. W. H. rals, metals, and their chemical composition. For example, the Freeman, New York 1986. discovery of aqua regia derived from vitriol and sal ammoniac 12. See ref. 9, n. 10, p. 564. robbed gold of its status as an indestructible metal, for now it 13. Levey M.: ISIS 49, 166 (1958). could be dissolved, or ìkilledî as some alchemists would say. 14. Galen: Opera (Kuhn K. G., ed.), Vol. 12, p. 238ñ241. C. Second, nitric acid was a potent solvent that led to improved Knobloch, Leipzig 1821ñ1831. methods for parting gold from silver and to the preparation of 15. von Lippmann E. O.: Entstehung und Ausbreitung der numerous new salts. Indeed, green vitriol was often referred Alchemie (Reprint of the ed. Springer Verl., Berlin 1919), to as ìthe green lionî in alchemical terminology, and the p. 42. G. Olms, Hildesheim 1978. corrosive elixirs extracted therefrom caused it to be the subject 16. See ref. 15, pp. 79, 90. of much secrecy, allegory, and interesting imagery in four- 17. Caley E. R.: J. Chem. Educ. 3, 1149 (1926). teenth century alchemical texts. Vitriolís crucial role in the 18. Newman W. R.: The Summa Perfectionis of Pseudo-Ge- preparation of nitric and sulfuric acids deserves deeper analy- ber. A Critical Edition, Translation & Study,p.111.E.J. sis, particularly concerning the recipe in the Summa perfec- Brill, Leiden 1991. tionis which might actually be a preparation for sulfuric acid. 19. Multhauf R. P.: The Origins of Chemistry, p. 139. Old- Meanwhile, familiarity with vitriol resulting from indus- bourne Book Co., London 1966. trial and laboratory practices led to an impressive chemical 20. Ullmann M.: Die Natur- und Geisteswissenschaften im and compositional exploration of this substance, beginning at Islam, p. 140ff. E. J. Brill, Leiden 1972. least as far back as the first century AD. The spectacular 21. Syed Nomanul Haq: Names, Natures and Things. The reaction in which solid iron reacts with a vitriol solution, which Alchemist Jabir ibn Hayyan and his Kitab al-Ahjar (Book is understood today as the reduction of cupric ions by iron from of Stones). Kluwer, Dordrecht 1994. a solution containing copper sulfate, was known to the Chine- 22. Ruska J.: Das Buch der Alaune und Salze, p. 120. Verl. se, Indians, and Arabs. This reaction drew considerable atten- Chemie, Berlin 1935. tion in sixteenth century Europe as a process from which both 23. Bose D. M., Sen S. N., Subbarayappa B. V.: A Concise craftsmen and alchemists profited. The former used this reac- History of Science in India. Indian National Science tion in the hydrometallurgy of copper and for enriching their Academy, New Delhi 1971. manufactured vitriol in iron, while alchemists cited it as a re- 24. Ray A. P.: History of Chemistry in Ancient and Medieval In- peatable and apparently undeniable example of the transmu- dia, Chap. II, III. Indian Chemical Society, Calcutta 1956. tation of metals. The understanding of vitriolís composition 25. Theophilus: On Divers Arts. (Transl. Hawthorne J. G., and chemical effects obtained by the pre-modern workers in Smith C. J.), p. 42. Dover Publ., New York 1979. the chemical fields constitutes an important chapter in the 26. See ref. 19, p. 170. history of mineral chemistry; for it reveals an interesting 27. Stillman J. M.: The Story of Alchemy and Early Chemi- interplay between observation (concerning the natural forma- stry, p. 185. Dover Publ., New York 1960. tion of vitriol and its related substances), empirical knowledge 28. Albertus Magnus: Book of Minerals (Transl. Wyckoff (concerning vitriolís composition, chemical uses, and the de- D.), p. 243. Clarendon Press, Oxford 1967. velopment of extraction processes), and theory (concerning 29. See ref. 8, p. 109. vitriolís mineral identity and its remarkable chemical effects). 30. Biringuccio V.: The Pirotechnia (Transl. Smith C. S., Gnudi M. T.), p. 98. Dover Publ., New York 1990. REFERENCES 31. Ercker L.: Treatise on Ores and Assaying (1574). (Transl. of the German original Beschreibung Allerf¸rnemisten 1. Weyer J., in the book: Alchemie. Lexikon einer hermeti- Mineralischen Ertzt, Frankfurt 1580, Sisco A. G., Smith schen Wissenschaft (Priesner C., Figala K., eds.), p. 124. C. S., eds.), pp. 152, 215ñ216. Univ. of Chicago Press, C. H. Beck, M¸nchen 1998. Chicago 1951.

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32. Ercker L.: Bergwerk- u. Probierb¸chlein. (Transl. Sisco tischen Wissenschaft (Priesner C., Figala K., eds.), p. 311. A. G., Smith C. S.), pp. 110, 153. AIME, New York 1949. C. H. Beck, M¸nchen 1998. 33. See ref. 9. 61. Die Alchemie des Geber (¸bers. u. erkl‰rt von Darmstaed- 34. See ref. 30, pp. 95ñ98. ter E.), p. 82 and n. 155. J. Springer Verl., Berlin 1922. 35. See ref. 9, pp. 572ñ578. 62. See ref. 18, p. 758. 36. See ref. 9, p. 578. 63. Die Alchemie des Andreas Libavius. Ein Lehrbuch der 37. See ref. 31, pp. 312ñ313. Chemie aus dem Jahre 1597, p. 451ff. Verl. Chemie, 38. See ref. 31, pp. 18, 95, 211, 218. Weinheim 1964. 39. See ref. 19, p. 316. 64. Priesner C.: Wolfenb¸tteler Forsch. 32, 107 (1986). 40. See ref. 31, p. 223. 65. See ref. 54. 41. Karpenko V.: J. Chem. Educ. 72, 1095 (1995). 66. See ref. 58, p. 131 ff. 42. Tsíao Tíien-chíin, Ho Ping-yu, Needham J.: Ambix 7, 67. See ref. 59, p. 48 ff. 144 (1959). 68. Mellor J. W.: A Comprehensive Treatise on Inorganic 43. Bromehead C. N., in the book: A History of Technology and Theoretical Chemistry, Vol. X, p. 372. Longmans & (Singer Ch., Holmyard E. J., et al., eds.), Vol. 2, p. 11. Green, London 1930. Clarendon Press, Oxford 1957. 44. Paracelsus: Economy of Minerals, in the book The Her- V. Karpenkoa and J. A. Norrisb (aDepartment of Physical metic and Alchemical Writings of Paracelsus (Transl. and Macromolecular Chemistry and bDepartment of Philo- Waite A. E.), Vol. 1, Chap. XVI, p. 104. The Alchemical sophy and History of Natural Sciences, Faculty of Science, Press, Edmonds 1992. Charles University, Prague): Vitriol in the History of Che- 45. See ref. 44, Vol. 1, pp. 102ñ103. mistry 46. See ref. 44, Vol. 1, p. 28. 47. See ref. 44. 48. See ref. 44, Vol. 1, p. 103. Vitriols, known today as sulfates of divalent metals, played 49. Sala A.: Anatomia vitrioli. Geneve 1609. an important role in the development of modern chemical and 50. Gantenbein U. L.: Der Chemiater Angelus Sala 1576ñ metallurgical practice, and engaged the speculation of alche- 1637. Juris Druck + Verl., Dietikon 1992. mists and mineralogists. The natural occurrence of vitriols and 51. Friedmann R.: Chemie in unserer Zeit 14, 191 (1980). its earliest recognition as a distinct group of related minerals 52. Boyle R.: Experiments, Notes &c. about the Mechanical is discussed. The unique position of vitriols was codified in Origin or Production of Divers Particular Qualities, al-R·zÌís (854-925/935 AD) classification of mineral substan- 1675, from Boyle R.: Works (Birch T., ed.), Vol. 4, ces. On the contrary, although considered to be a noteworthy p. 329ff., 1772. mineral substance in Indian alchemy, vitriol is not recognized 53. Horlacher C.: Kern und Stern der vornehmsten Chy- as a distinct mineral, the blue and green varieties being classed misch=Philosophischen Schrifften, p. 101. (facsimile of separately according to other criteria. The deposition of Cu the edition Frankfurt 1707) Akademische Druck- u. Ver- from a vitriol solution on an iron surface was known in some lagsanstalt, Graz 1975. ancient cultures, and it became even used on an industrial scale 54. Newman W. R.: Sudhoffs Archiv, Band 69, Heft 1 in the 11th and 12th centuries AD. These reactions, which were (1985), p. 76. sometimes construed as an apparent transmutation of metals, 55. SchwartzA. T., Kauffman G. B.: J. Chem. Educ. 53, 235 were further investigated and were significant for European (1976). alchemy and mineralogy. The practice of preparation of nitric 56. See ref. 30, p. 186. acid from vitriol, which seems to have begun around 1300, 57. See ref. 9, p. 439 ff. soon increased the number of known chemical reactions. Aqua 58. Soukup R. W., Mayer H.: Alchemistisches Gold. Para- regia was a further innovation that made possible the dissolu- celsische Pharmaka, p. 139. Bˆhlau Verl., Wien 1997. tion of gold, which had previously been considered as the 59. Schrˆder G.: Die pharmazeutisch-chemischen Produkte indestructible metal. Particular attention is paid to the prepa- deutscher Apotheken im Zeitalter der Chemiatrie, p. 61ff. ration of sulfuric acid from vitriol. Several descriptions of Verˆffentlichungen aus dem pharmaziegeschichtlichen a red solution obtained during this process lead to the consi- Seminar der Technischen Hochschule Braunschweig, deration of a process from the Summa Perfectionis of Pseudo- Bremen 1957. -Geber that could have resulted in sulfuric acid, and in which 60. Priesner C., in the book: Alchemie. Lexikon einer herme- contamination with Se could have led to the red product.

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