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most cases important that he should be given by the appointment of Prof. Lennard-Jones as leave of absence at regular intervals, and encour• professor of theoretical physics. In addition, the aged to visit other scientific centres, whether at institution of research fellowships to attract to home or abroad, and to get into personal contact the laboratory young men who have shown marked with the workers in his special field. The value of ability for research is a step in the right direction, such 'refresher' intervals is difficult to exaggerate, and I hope that it will be possible in the near future whether to the individual or the institution which to add to their number. Under such excellent he serves. I am sure that there are few scientific conditions we may confidently anticipate that this men that would not benefit by such opportunities. laboratory will fulfil the wishes of the donor by At no time in the history of physics has there developing into one of our most important centres been a closer co-operation and sympathy between of training and research. the two great branches of physics, the experimental The University owes much to the public spirit and theoretical. With the ever-growing complexity shown by the city of Bristol and to the wise of experimentation and technique, it is rare in generosity of its citizens. I am sure that all these days that a scientific man can claim to be scientific men are grateful to the University proficient in both of these branches. There has and to the donor, Mr. Henry Herbert Wills, thus arisen the need that these complementary whose generous benefactions have made possible divisions should be adequately represented in a the erection and endowment of this splendid Department of Physics. I am very glad to see laboratory dedicated to the pursuit of scientific that this has been recognised in your University knowledge.

Marcelin Berthelot.1 By Prof. HENRY E. ARMSTRONG, F.R.S. HE highest testimony we can giVe to the still alive who knew him, though not at the be• T genius of a departed colleague is to study ginning of .. Ujls hope that these will his work and its bearings, as in such exercise we I give us of the" that will enable are bound to find food for thought and gather us to follow sychological development as a inspiration for the future. As one of the older worker. For Pasteur we apparently have this chemists, I would fain bear such slight witness as information ; the lessons :Jl from it are in• I may to the effect and value of Berthelot's valuable. Weee to Jhe clearest under• achievements, being the more inclined to this task standing of is t ra e t and to be able to from having noticed, in the younger generation, follow the g dual unfolding of his powers : to a strange lack of interest in the pioneers who laid appreciate the masterly logic of his disposition: the foundations of the science they would master, to see one continuous line of thought pervading now so mighty a structure--even a failure to all his labours, above all, his desire to serve his understand the language these pioneers used. fellows. Berthelot offers a surprising contrast : Continuity with the past is desirable, if only in we know so little of the man. His seems to have order that we may understand the mental attitude been a more universal genius. We are in sore need of inquirers at the time they undertook their of some thread of continuity to guide us through labours and be in a position to evaluate the mental the maze of his mind. development of their ideas. No episode in the history of chemical science is Berthelot himself, who seems to have been of greater interest than that of the discovery of extremely well read even at an early age, through dephlogisticated air by Priestley and the instant his studies of the alchemists endeavoured to shed appreciation of its vallle by Lavoisier-conveyed light upon the beginnings of chemistry and has in the magic word ' oxygen,' a word, however, thereby made elear the extraordinary difficulty the magic of which is not heard by young ears of the task. Few to-day can appreciate his own to-day, even in France. ·we can, in a measure, rigid attitude towards atomic weights-how it was put ourselves into Lavoisier's position-our habit that he wrote C = 6 and 0 = 8 almost up to the last. of thought still being largely that which he in• If his intimate story could be written, it would troduced in raising chemistry from an empiric art probably be one of a mind ever striving to be to a philosophy. We can no longer enter into the scientific, yet held in the thrall of that superhuman spirit of Priestley's work-we cannot even read force we term conservatism : the force by which his language with understanding. He has been our human society is held together and bound• commonly regarded as a pure empiric, but it is the instinct of the herd-thro\lgh the exercise of impossible to give credit to such estimate of his which we alone survive. On the other hand, it character. Berthelot, indeed, has questioned the also separates us and especially from the past---• truth of his representation of himself as an empiric. as each new faith tends to antagonise the mind There are numerous passages in his works which of its holder against an earlier form. may be interpreted as proof that behind all his The rising generation has little if any under• inquiries there was both method and logical standing of the language spoken even so recently as purpose, though maybe the purpose of intuition in Berthelot's early days. There are, however, men only. In the preface to his collected works (1790), ' The English original of an 'appreciation' contributed to Chimie he himself advocates philosophical studies in the et Irulustrie in connexion with the centenary celebrations of Marcelin Berthelot. following most remarkable passage : No. 3027, VoL. 120]

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I am sorry to have occasion to observe that natural 1 as each new number came to hand. Some point science is very little, if at all, the object of educat-ion he always made. His method had the advantage in this country, in which many individuals have distinguished themselves so much by their applica• that he made his points singly, so they went home. tion to it. And I would obset"VO that, if we wish to Myself a student under Hofmann, Frankland and lay a good foundation for a philosophical taste and Kolbe, three of the great pioneersofourscienceon the philosophical pursuits, persons :should be accm:tomed organic side, I was specially prepared to appreciate to the sight of experiments and processes in early Berthelot's early suceesses in synthetic chemistry. life. They should more especially be initiated in the theory and practice of investigation by which many Few to-day will realise how grettt was the impression of the old discoveries may be made to be really their he made by his production of alcohol from ethylene own-on which and water, of account they formic acid will bo much more valued by from carbonic them. And, in oxide and soda, a great variety of acetylene of articles, very from carbon young persons and hydrogen may be n1ade so far acquainted - this last a with everything particu I arly necessary to be striking dis• previously covery at the known as t,o time when we engage (which were beginning they will do with particular alac• to specify or• rity) in pursuits ganic chemis• truly original. try as the chemistry of Nowhere, in hydrocarbons our schools, and their deri• have we yet vatives. The acted up to barrier between these recom• the livingworld mendations : and the labora• we pay faint tory had in• heed to them deed been even in our broken down, colleges. in 1828, by ltismygood Wohler's fortune to be achievement in able to over• preparing look the period from ammorua from 1865 to and cyanic acid, the present but this was a time-an inter• case of Berze• val of more lian metameric than sixty change, not years. I still synthesis. Ber• remember how thelot went greatly, at the much further beginning of M.utCELIN BERTHELOT. and fired our my career, I imagination by was fascinated by Berthelot's achievements, especi• showing how two and two might be put to• ally by reading his book on organic synthesis ( 1860). gether to make four and in ways which were 1£nglish chemists, I may say, have always been extraordinary in their directness and simplicity. accustomed to pay close attention to the work of Not only was our vision greatly extended but their French colleagues, especially that published our ambitions also became boundless. We saw in the Comptes rendus de l Academie des Sciences. that the pass over the heights was won and Not only is the concise form in which work is there that the conquest of the great kingdom beyond presented eminently attractive but also, almost was a mere matter of time. We now seem able invariably, the force of genius is apparent in each to make what we will, when once we know what communication, some new idea being stated, some we are called upon to do. No plant is safe from advance recorded. Moreover, Berthelot compelled our imitation. The world is arrayed in laboratory attention by his persistent appearance on the boards products. Where our forefathers used woad as a week after week. "What has he to say this source of indigotin, we use the pure pigment, was the unconscious question we asked ourselves, made by thousands of tons in our factories. The No. 3027, VoL. 120]

© 1927 Nature Publishing Group NOVEMBER 5, ] 927] NATURE 661 purple used by emperors in the past, laboriously verbal meaning: that of putting together, in the extracted from multitudinous shell-fish, is now a fashion so perfectly set by Berthelot, by working relatively inexpensive laboratory product. We all upwards from simple to complex. To give an but laugh at Nature-in fact, we can do more example, oxalic acid may be made analytically by than she elects to do and arrogantly wear two gloves oxidation of sugar ; it may be synthesised through where she is content with but one ; this, her prime cyanogen, NC. CN. We have reason, however, secret, however, is her security, it seems, one for to believe that in no case are compounds formed which _Berthelot did not allow when he suggested directly merely from their atomic constituents. that, m the future, perhaps we should live on The production of acetylene, in fact, is a highly synthetic food-an unpardonable suggestion for a complex process, involving as it does not only the man belonging to a gastronomic nation to make, a resolution of the diatomic hydrogen molecule but clear blot upon his shield. Chemists, it is true, are also that of the carbon complex Cx, where X is an cooks but the French cook is by heredity an artist unknown but probably very high value. The and his art one to be held in reverence, not inter• equation may be written fered with by science and spoilt-as is brewing. xH + 2Cx = xC H • Still, the example which we perforce have followed, 2 2 2 in our mad career of wresting so much of her In result only is the synthesis simple. If we from Nature, is that set by Berthelot. accept Faraday's teaching, the process is still more His methods of producing alcohol and formic acid complex, involving other factors which make the long remained in abeyance-there was no call for occurrence of change possible by the inclusion of their application ; in recent years, however, they the interacting materials in an electrolytic circuit. have been developed on the large scale. That of The same may be said of calcium carbide. There acetylene may be ranked as the most fruitful of is good reason to believe that, in preparing this his discoveries. Produced by the calcium carbide substance, by heating carbon with lime, in an process, which in its essence is Berthelot's, this electric arc, we are but producing calcium in situ gas is now used not only as an illuminant but also and that the carbide is formed by the interaction in the form of the acetylene blowpipe, in welding of carbon and the metal-again under the influence and cutting steel. Acetylene is also used as the of factors which together with these constitute an primary material in the production of acetic acid electrolytic circuit. The argument is equally on large scale. If, to-day, though we do not applicable to the synthesis of alcohol from ethylene despise Nature, we are tending to put her aside and of a formate from carbonic oxide. and make coal the universal raw material, the The germ of Berthelot's synthetic achievements initial fault was Berthelot's; if to do so be a is already forecast in his first chemical essay• virtue, the credit lies equally with him. " Action de la chaleur rouge sur l'alcool et sur Regarding Berthelot, as we must, as the parent l'acide acetique" (Annal. de Chimie, 33, 295; 1851). of synthetic organic chemistry, we need to be clear This inquiry was undertaken to ascertain what in our definition of synthesis, in view of the too would happen if simple substances were submitted general tendency to attach loose meanings to the to a red-heat, as nearly all organic substances of terms we use and of the danger we run, especially high atomic weight gave similar products, coal-tar at legal hands, of our terms being misinterpreted being an example. His experiments proved that by those who have no feeling for their use. the hydrocarbons benzene and naphthalene, phenol We do well to remember the caution given by and various other complex compounds were equally Gerhardt in the preface to his " Introduction a obtainable from the simple substances and so laid l'etude de la chimie" (Montpellier, Fev. 1848): the foundation of pyrogenic synthesis. In his essay he insists, in the most definite manner J'ai cherche, autant que possible, a joindre, dans possible, that the synthesis of benzene, naphthalene, !'explication des phenomt'mes, la precision a la clarM, prenant en cela pour modele les mathematiciens qui etc., from their elements could henceforth be ne se servent jamais d'un terme sans en avoir pre• regarded as a fait accompli, inasmuch as acetic alablement etabli le sens. Il faudra bien un jour acid, from which he had prepared them, had arriver a ecrire les livres de la chimie comme on already been produced synthetically, by Kolbe, em·it une geometrie ou une algebre; c'est alors commencing with carbon bisulphide. seulement que la chimie se repandra davantage dans Berthelot, therefore, from the outset, was pre• les masses. pared to give a wide definition of the term synthesis In the following passage Gerhardt uses synthesis and obviously interpreted it in the sense of the as the antithesis of analysis : passage quoted above from Gerhardt, whose writings will have been known to him. Moreover, Les operations de la chimie sont de deux especes : he clearly recognises that Kolbe was his forerunner. ell_e determine les metamorphoses, soit par analyse, smt par synthBse ; elle separe de la :matiere tout.es The essay is striking testimony to the early les parties dissemblables, ou, par un precede inverse, development of his genius. elle unit ces parties entre elles ; elle decompose ou Milestones remain from which we may infer the elle recompose. L'activite inherente a la matiere est state of knowledge at the time when his synthetic son moyen ; le chimiste la provoque par le contact work was begun. The volume of Liebig's Annalen immediat des corps heterogenes ; il la renforce ou (81; 1852) in which Berthelot's essay is reprinted l'affaiblit par l'intermediaire des agents physiques chaleur, electricite, lumiere. ' from the A nnales de Chimie also contains Alexander Williamson's celebrated memoir on the formation The word synthesis can only be given its proper of ether. In this, as is well known, the long No. 3027, VoL. 1201 © 1927 Nature Publishing Group 662 NATURE [NOVEMBER 5, 1927 standing dispite over the relationship of alcohol Aeetylene, if not his discovery, W<1S fir:-;t char• and ether was finally settled and the constitution acterised by him and eventually synthesised from o£ the two compounds made clear. The :-;tudent its elements. As this is the most fundamental of of to-day has difficulty in pieturing the erudity all syntheses and the ga::; is of grca t technical of belief and the slight body of knowledge of his importance, his name will always be indissolubly forerunner of those by no means far away times. linked by chemists with this hydrocarbon and its Williamson's interpretation was a master stroke direct conversion into benzene. of genius but an absolute ' bolt from the blue,' Persulphonic anhydride and pcrsulphonic acid taking into aeeount the unecrtainty, if not con• are probably to be ranked as his most important fusion, which prevailed. We know that when he primary chemical discoveries. undertook the inquiry, he had not in mind the The most difficult chapter in Berthelot's work problem of which, as he ultimately saw, it gave to appraise is the thermochemical, including that the solution. I have vainly sought for a clue to of explosive combustion. Bver a fundamentalist his mental development up to the stage when he at heart, in this, a:-; in all his other work, he sought suddenly took so great a step forward and defined for primary vttlues. Commencing in 1865,. it for all time the alcoholic and etheric functiom;. covers a wide range. The earlier data are probably The nearest approach to an explanation which uneertain in not a few eases. In this, as in most may be offered is, that he was under the Hpell of other sections of his work, he was opening up ;1 Gerhardt's logical genius, as may be inferred from new field of inquiry and methods had to be devised the consistent manner in which he (also hi:-; friend and developed. Sueh work, moreover, Wt1S scarcely Kekule) made use of 'typical ' forrnuhe from this suited to his imaginative temperament and im• time onwards. The alcohol-ether problem was petuous mode of attack. It needs not only a ripe for solution, in faet, owing to the publication highly developed sense of accuracy but also a of Gerhardt's advanced theoretical views. persistence and patience and a self-denial which Another article of speeial historical interest, in few possess. He came into conflict with Julius connexion with Berthelot's work, in the volume of Thomsen, who was making thermochemical Liebig's Annalen referred to, is a letter from measurement his life work; usually, in the end, Hofmann to Liebig on" The Applieation of Organic they were in agreement. Berthelot probably de• Chemistry to Perfumery." Hofmann prefaces his rived his interest in such work from the example aceount by direeting attention to Cahour's work on set by his great countrymen Lavoisier and Laplace. the oil of Ganltheria procnmbens, showing it to be He sought to generalise and so was led to formulate a eompound ether. He sees proof of the influence his well- known three principles. Ultimately he this had upon perfumers in the appearance in our rendered a service which it is difficult to over• first English Exhibition (1851) of numerous fruit estimate by his invention of the calorimetrie bomb, ethers and describes the results of his examination one of the most powerful engines of researeh yet of various samples which he had collected as a devised. Maybe the principle embodied in its juryman-he had found the ' pear oil ' to be usc will some day be utilised in the internal amylic acetate, the ' apple oil ' amylic valerate, combustion engine, when oil is no longer available the' pine-apple oil' ethylic butyrate, etc. To-day, as a cheap fuel. Hitherto it has been lmed chiefly such synthetic materials are used not only in in estimating the calorific value of fuels but it has perfumery but also, on a huge scale, as solvents also been of service in analysis. in the cellulose and varnish industries. Berthelot In fact, thermochemistry seems almost to be a soon afterwards became interested in the more subject of the past. Few to-day will realise how eomplex etheral salts and, in fact, began his great was the interest we took in Berthelot's and synthetic eampaign by building up fats artificially Thomsen's results as they were published. Testi• from glyeerol and fatty acids, thus crowning the mony to my own interest in the subject is to be work o£ his great countryman Chevreul. found in the article "Chemistry," which I wrote The inquiry that has received more attention for the" Encycloprodia Britannica" (vol. 5, eel. 9), perhaps than any other published under his name published in 1876. I then quoted characteristic and probably is the most esteemed is that on thermal data for most of the elements. etherification, in which he was associated with It is unfortunate that chemists now so rarely Pean de St. Gilles. Carried out with exceptional take thermochemical values into con:-;ideration. care and finish, dealing with a fundamental problem When this is done, interpretations which on the of the highest interest, akin to that which William• surface may seem plau:-;iblc are often prenluded. son had dealt with in his interpretation of the An example may he found in the enigmatic conditions of metallic Sttlts in aqueous solution, behaviour of carbonic oxide. As H. B. Dixon the inquiry cxeited the widest interest and was was the first to show, this gas in admixture with the prototype of many similar inquiries-none the oxygen is incombustible when dried, although if less, even now, we are not fully informed nor agreed the mixture be moistened it explodes, the rate of as to the precise nature of the process. combustion being more rapid the more moisture A branch of Berthelot's work which appealed to is present up to a certain point. This behaviour me in my early days was that upon oil of tur• has been interpreted as proof that combustion pentine, in which again he appeared as a pioneer. takes plaee through the agency of 'water' in He was the first to distingui::;h between the oils accordance with the equation from various sources and cspeeially to note the CO+ OH2 =C02 + H 2. distinctive differences in optical properties. This interpretation ifl precluded, however, by the No. 3027, VoL. 1201 © 1927 Nature Publishing Group N OVE:MBER 5, 1927] NATURE 663 fact that the heat of combustion of hydrogen to carbon, made at a time when the methods were liquid water is greater than that of carbonic oxide. but imperfectly developed. Wieland has shown that such an interaction Berthelot, with Petit, made use of his calorimetric apparently does take place under the influence of bomb in redetermining the value of carbon in its palladium black but he goes further: having reputed three forms. They give as the means of observed that traces of formic acid are present closely accordant determinations the ' atomic in the liquid, he argues that formic acid is the values' first product : Diamond 94,310 gram-degree Centigrade units CO + OH2 = H 2C02, Graphite 94,810 " and that this is deprived of hydrogen by the action Charcoal 96,960 of the palladium Apart from the question as t,o which of the forms C02H 2 = C02 + H 2. the theoretical heats of formation of carbon com• As formic acid has a higher heat of combustion pounds may properly be referred, we have yet to than carbonic oxide, the formation of the acid show that there are forms of carbon other than the from the gas would be an endothermic process. diamond. Now that there is reason to suppose, On this ground, Wieland's modified interpretation in view of Sir Charles Parsons's inquiries, that of the combustion process must equally be ruled diamond has never been produced artificially, the out of order. problem is raised to an acute stage. The prob• On thermo- and electro-chemical grounds we ability is that the reported allotropes of diamond may go even further and premise that carbonic (graphite and charcoal) are hydrocarbons con• oxide cannot be burnt by ordinary oxygen, even taining the minute proportion of hydrogen needed when all other necessary determinative conditions to prevent the carbon atoms from lapsing into are realised. On the assumption that every the highly stable condition they present in diamond, chemical interchange is an electrolytic process, owing to the symmetrical, uniformly tetrahedral whenever 'conducting water' is present as a arrangement of the atomic units. The very small necessary element in the circuit in which inter• difference between diamond and graphite, the change is effected, no action should take place at relatively large difference between graphite and any potential below that developed in the formation charcoal are both surprising. We cannot accept of water from hydrogen and oxygen. To burn even Berthelot and Petit's determinations as final. carbonic oxide, it is necessary therefore to use an A worthy monument to Berthelot's memory and oxidising agent of higher potential than ordinary genius would be an institute charged with the duty oxygen, the heat of combustion of carbonic oxide of placing beyond question all the fundamental being below that of hydrogen. Hydrogen peroxide thermal values and of extending thermochemical is such an agent. This oxide is a product of the study in general. A vast field of fruitful inquiry primary interaction when hydrogen is burnt lies open in the hydrocarbons especially. It is impossible to contemplate the long list of H I HO ... H I 0 H20 I" . ·j HO titles-about 1500-to which his name is attached without feeling that justice remains to be done to H HO ... H 0 H 0 . . . HO. 2 his phenomenal activity. We need a studied, To explain the fact that a moist mixture of carbonic critical analysis of his work, in which the logic of oxide and ordinary oxygen is explosive, we therefore his progress is fitly displayed. The work of poets need only to assume that on firing the mixture a is considered line by line : their critics seek to minute quantity of water is decomposed : that reconcile the miracles they have wrought in words the liberated hydrogen is then at once peroxidised with the peculiarities, if not deficiencies, of their and that the hydrogen peroxide thus produced moral character. The characters of statesmen, of serves to oxidise the equivalent amount of carbonic soldiers, sailors and explorers are often discussed oxide. All the peculiarities in the behaviour of in considering their deeds. Little has been done carbonic oxide on combustion are accounted for by to analyse the psychology of the scientific mind, these assumptions. to define the special features of the scientific spirit, The halting use hitherto made of thermochemical yet even poets have foreseen that it is the spirit data is due, in no slight measure, to a suspicion of the future. With most wonderful prescience that the values, in not a few cases, are of doubtful Shelley has said of man : accuracy. The difficulty of interpreting the ob• "All things confess his strength. . . . served values is a still greater bar. These are all . . based upon the study of molecular interactions, The lightning is his slave ; heaven's utmost deep often complex in character, the direct determination Gives up her stars and like a flock of sheep of atomic values being impossible. The difficulty They pass before his eye, are numbered and roll on ! has been in part met, in recent years, by resort to The tempest is his steed, he strides the air thermo-dynamical reasoning and the introduction And tho abyss shouts from her depth laid bare, ' Heaven, hast thou secrets ? Man unveils me; I of ' electrolytic ' methods. have none!'" We are in face of this difficulty especially in the case of carbon. Julius Thomsen's numerous Of such order was Berthelot. We need to have calculated values for carbon compounds were all the strength of the scientific mind fully unveiled : based upon Favre and Silbermann's determination its weaknesses too, so that we may seek to combat (1842--43) of the heat of combustion of charcoal them in the future service of the world. No. 3027, VoL. 120] © 1927 Nature Publishing Group