ET LES DEBUTS
DE LA SCIENCE MODERNE
Irene Strube (German Democratic Republic)
THE ROLE OF ANCIENT ATOMISM IN THE EVOLUTION OF CHEMICAL RESEARCH
IN THE SECOND HALF OF THE 17th CENTURY
Discourses on chemical changes of m a tte r carried on in th e second half of th e 17th century proceeded from a basis differing from the preceding by an essential topic: the tasks th a t men like S en n ert and Jungius had set them selves had still been b uilt u p on universal n a tu ra l philosophy. These tasks had m ainly been lim ited to pointing o u t in congruities betw een the Scholastic doctrines and th e em erging labora tory experience of chemists, and to in terp retin g anew these recent findings on the basis of th e rediscovered ancient theories on corpuscles.
However, in th e la tte r p a rt of the 17th century there began to take root new concepts th a t had been developed by Galilei, Bacon and Des cartes on the essence and tasks of science; these concepts contributed m uch to releasing chem istry from the fetters inflicted by n atu ra l philo sophy, and to advance it to th e status of an independent science w ith its own field of research. In 1663 Boyle p u t forw ard th e opinion th a t the study of n a tu re is not lim ited to yielding joy, “as it teaches us to know nature, b u t also as it teaches us in m any cases to m aster and command it. For the tru e naturalist... does not only know m any things w hich other men ignore, b ut can perform m any things w hich other men cannot do, being unable by his skill n o t barely to u n d er stand several wonders of nature, b u t also p artly to im itate, and p artly to m ultiply and im prove them .” (Some considerations touching the use fulness of experim ental natural philosophy, 2nd ed, Oxford 1664, p. 19.) The essentially new message brought by these w idened tasks to the evolution of chemical knowledge was th a t henceforth chemical experi m ents came to be acknowledged as the gauge by which the veracity of a new theory could be appraised. Thus one of the fundam ental requirem ents dem anded by Boyle a t th e beginning of this evolution
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was: to experim ent, to observe, not to announce any theories w ithout previously scrutinizing th e ir respective resu lts by experim ents.
The task prom ulgated by Boyle, in p articu lar in his w ritings on chem istry, w as therefore m uch m ore comprehensive. Its essence was to in terp ret in a new way the qualitative transform ation of m atter, b u t at the same tim e to determ ine th e essence of these qualitative transform ations by chemical experim ents. While these experim ents m erely represented an initial stage, y e t they w ere of g reat im portance for th e fu rth e r evolution of chem istry because, on the one hand, Boyle succeeded in developing the foundations of the qualitative analysis and, on the other, he m anaged by m eans of his unfailing and always repeatable experim ents to point out very im pressively the shortcomings of th e scholastic doctrines and to procure a much w ider appreciation to the atom istic theories, w hich he resum ed and expanded.
In elaborating his theoretical assertions Boyle was able to use as basis the statu s attained in the first half of th e 17th century by scientists like Jungius, by their resum ption of the ancient doctrine on corpuscles. If, nevertheless, Boyle consigned a w ider space to his critical attitu d e tow ards the scholastic doctrine on substantial forms, his prim e intention m ust have been to overcome th e m utual concessions entered into since th e end of the 16th century betw een th e theories of forms and those of corpuscles. He declared th a t: “Nothing in n a tu re is com posed of m atter and a distinct substance, b u t m an.” (The W orks of the Honourable R. Boyle, vol. I, ed. by R. Boulton, London 1699, p. 32.)
The cause of qualitative transform ations of substances is not a change brought about by a form inflicted by exterior agencies, but—as had been stressed by Jungius a t an earlier date—th e m utual influence of th e corpuscles of the partaking substances.
Boyle considered him self justified to this conclusion by reason of his practical experience, He w rote: “For, besides th a t which happens in th e generation, corruption, nutrition and w asting of bodies, not only chym ical resolutions, b ut microscopes discover bodies to consist of parts, very m inute, and of different figures.” (The W orks, vol. IV, London 1700, p. 29.)
Even so, Boyle did not rely exclusively on Jun g iu s’ works. The treatises published by D. Sennert, P. Gassendi and R. Descartes, as w ell as Epicurus’ and L ucretius’ w ritings w ere known to him in th eir m ain parts. He gathered from these data w hatever he deemed suitable for elucidating chemical processes, and he criticized the ancient atom theories m erely because of th e ir atheistic character.
As it is w ell known, in th e evolution of his own doctrine on corpus cles Boyle started out from the following assum ption: “It seems not absurd to conceive, th a t a t th e first production of m ixed bodies, the
universal m atter ... w as actually divided into little particles of several sizes and shapes, variously moved.” (The W orks, IV, p. 29.)
On the basis of certain geom etrical conform ities in th e ir shapes, he supposed these m inute corpuscles to be capable of form ing corpuscle assemblages of divergent composition, in w hich the “po stu re”, the arrangem ent of the various constituent corpuscles in the assemblage, should be distinguished from the “te x tu re ”, the configuration the corpuscles assume in macroscopic bodies. In Boyle’s opinion, “p o stu re” and “te x tu re ” alone are the cause of the d ifferent qualities possessed by substances, and m a tter and motion are the only elem ents (principia) of the different bodies.
By thus consigning all m aterial properties and th eir transform ations to th e two elem ents: m atter and motion, Boyle came rem arkably near to the ancient atom theories of Democritus, Epicurus and Lucretius. However, in chem istry of those times th is reasoning represented an essential step ahead com pared w ith the scholastic teachings of forms, because Boyle again considered the qualitative transform ations of substances to be processes—processes m irroring an interio r mechanism of exteriorly observed changes of qualities, identifiable by analytical chem istry. In this w ay a decisive point of issue for a fu rth e r evolution of chem istry had been attained.
In consequence of the assum ption of a w orld lim ited to m a tter and motion as elem ents of m atter, there indeed had to be accepted an am endm ent in one of the m ain concepts of chem istry: in the notion of w hat is an elem ent. This was so, because th e concept of elem ents as w as held by the ancient chem ists—to tally unm ixed substances, dif feren t in quality, participating in the stru ctu re of the m ixed substances —had to lose its sense, if one assum ed corpuscles of a substance u n i form in quality to be the ultim ate simple constituents of chemical compounds. It is easy to prove th a t it w as from this stage of know ledge, th a t Boyle began his famous criticism of th e fo u r peripatetic elem ents fire, w ater, air and earth, and the th ree spagyric elem ents sulphur, m ercury and salt; even so, first he perform ed a great num ber of experim ents and observations for proving the untenability of these ancient concepts. The final conclusions draw n by Boyle from these ex perim ents—and it was principally M. Boas in h e r extensive investigations (M. Boas, R. Boyle and seventeenth century chem istry, Cam bridge 1958) who pointed this out—w ere as follows: 1) there is no necessity to assume, th a t all m ixed substances m ust alw ays be built up of w h at are called elements, and 2) the so-called elem ents of the P eripatetics and the Spagyrians are no elem ents a t all, no principia in the m eaning of th eir definition. A fu rth e r final conclusion, draw n by Boyle from his doctrine of corpuscles, was: th ere is no necessity a t all of this kind of elem ents to exist. As to tru e elements, th a t is, final principia, 9 — O r g a n o n , N r 4/67
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these are particles, each different in shape and different in its motion, of common m a tte r in general.
In spite of, or ra th e r on th e basis of, his critical attitu d e Boyle a t tem pted a fu rth e r step ahead, trying to evolve a new concept, th a t of a “chemical elem ent”; this w as an a tte m p t which, unfortunately, he abandoned and which, la te r on, Lavoisier succeeded in carying to a successful end.
Again it w as chemical experience th a t brought Boyle very n ear to conquering and to establishing this new concept of chem ical elem ents by m eans of his corpuscle theory. From his chemical experim ents he w as aw are— and this had already been stressed by Jungius—th a t there are certain arrangem ents of corpuscles w hich are v ery tenacious and durable; strong enough not to be split up by a variety of chemical transform ations into th e ir original composition. Among the exam ples m entioned by Boyle is the transform ation of gold into goldchloride (aqua regis), or of m ercury into m ercurychloride, as w ell as th e re covery of the m etals in th e ir original q u ality and q uan tity from these compounds. The relatively stable groups of corpuscles like gold and m ercury Boyle called “clusters” or, a t times, “p rim ary concretions”, as cribing th e ir stableness to th e m inute size and to the particularly intim ate union of the corpuscles form ing these clusters. I t was the concept of the existence of “clusters” of this type th a t brought Boyle very close to the new concept of a chem ical element. In this context th e “clu sters” would have to be looked upon as chemical elements, th a t is, as substances into w hich m ixed bodies are u ltim ately dissolved in chemical analyses, and gold and m ercury w ould therefore have to be called chem ical elements. The im pulse tow ards th is concept can indisputably be found in Boyle’s The Sceptical C h ym ist; even so, Boyle confined him self to this, and ra th e r he la te r abandoned this concept, again on the basis of experim ental observations. These, however, hap pened to be misleading, because Boyle imagined, th a t by the use of a very strong solvent he had dissolved even gold “clu sters” into then- individual corpuscles and arranged these corpuscles to form a new m etal. By reason of this and a num ber of fu rth e r observations Boyle ultim ately concluded, th a t no stable elem ents exist, th a t there is no need of recovering in the chemical analysis those substances th a t had been united by synthesis. Because, as Boyle argued: “hence it appears, th a t as the difference of bodies m ay depend m eerly upon the schemes into which th e ir common m a tter is p u t; so the seeds of things, th e fire and other agents, are able to a lte r the m inute p arts1 of a body: And the same agents, p artly by altering th e shape or bigness of th e con stitu e n t corpuscles of a body, p a rtly by driving aw ay some of them, p artly by blending others w ith them, and p a rtly by some new m anner of connecting them , m ay give th e whole portion of m atter a new tex tu re
of its m inute parts, and, thereby m ake it deserve a new and distinct nam e.” (The W orks, IV, p. 118.)
Thus, the adoption and consistent evolution of th e ancient doctrine on corpuscles by Boyle had diverse consequences in the fu rth e r de velopm ent of chem ical research in the la tte r h alf of th e 17th century: on th e one hand, com pared w ith th e scholastic doctrines of form s and m ixtures, Boyle’s w ork constituted a decisive advance fo r the experim ental possibilities of perception of m a tte r and its tra n s form ations. Hence m ay be explained th e strong reverberation incited by Boyle among his successors, like G. E. S tah l or, la te r on, Lomonosov who, as to himself, adm itted th a t from the tim e he h ad read Boyle he was seized by th e passionate desire to investigate th e most m inute particles (M. W. Lomonosov, Ausgew ahlte W erke, B erlin 1961, I, p. 9). On the other hand, however, Boyle’s concept to ascribe the chem istry of substances to th e physics of corpuscles, and to deny th e existence of chemical elem ents led to a situation, in w hich chem ists w ould have been unable to continue research on qualitativ e transform ations of m atter.
This explains th e critical attitu d e adopted by chem ists like N. L ém ery or G. E. S tahl concerning Boyle’s teachings.
U pholding the concept of the corpuscle theory, these chem ists principally undertook to look for the “elem ents” which, in th e ir opinion constituting stable m atter, w ould represent objects of reference in th e changes and transform ations taking place.
H ere again L ém ery cam e very n ear to establishing the concept of a “ chemical elem ent”, w hen in his argum ents against Boyle he asserts: “Quelques philosophes modernes veulent persu ad er q u ’il est incertain que les substances q u ’on retire des mixtes, e t que nous avons appelés Principes de Chymie, resident effectivem ent et natu rellem en t dans le m ixte: ils disent que le feu, en ra rifia n t la m atière dans les distillations, est capable de lu i donner ensuite un arran g em en t to u t d ifferent de celui q u ’elle av ait auparavant, e t de form er le sel, l’huile e t les au tre s choses q u ’on en tire .”
And, a t another place: “Le nom de Principe en Chymie, n e doit pas estre pris dans une signification to u t à fait exacte: car les substances à qui l’on a donné ce nom ne sont principes q u ’à no tre égard, et q u ’en ta n t que nous ne pouvons point aller plus av an t dans la division des corps: m ais on com prend bien que ces principes sont encore divisibles en une infinité de p arties qui pourraien à plus ju ste titre estre appellées Principes. On n ’entend donc p a r principes de Chymie que des substances separées e t divisées au ta n t que nos faibles efforts en sont capables”. (Cours de Chymie, Onzième édition, à Leyde, 1716, pp. 5f.)
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in certain of the ancient peripatetic or spagyric elem ents, and by this belief he again retre ated a full step behind Boyle.
It was only tow ards the end of th e 17th cen tu ry th a t G. E. S tahl w ent a step ahead beyond J. J. Becher’s experim ents: in his efforts to explain the chem ical processes during m etal sm elting, he discovered the essence of reduction and oxidation, ascribing this feat to his phlogiston. A fterw ards, the change-over proceeding tow ards the phlogiston theory as general chemical theory did not constitute any break w ith the evolution reached up to then; it was not a resum ption of occult qualities and scholastic beliefs as has often been maintained. On the contrary, it was th e unavoidable evolution of Boyle’s teachings, because S tah l’s phlogiston theory was based, on th e one hand, on Ju n g iu s’ and Boyle’s doctrine on corpuscles^—as fa r as th e mechanisms of chemical reactions w ere concerned—and, on the other, this theory w as an attem p t of perceiving in phlogiston a tru e chemical element, whose corpuscles partak e in th e reactions of oxidation and reduction and en ter into th e com pounds of substances (I. Strube, “Die Phlogiston- lehre G. E. S tahle in ih rer historischen B edeutung”, Zeitschr. fu r Ge- schichte der Naturw issenschaften, T echnik und M edizin ( NTM) 1961,2).
In v irtu e of th e resum ption of th e ancient doctrine on corpuscles and of its evolution by chemical practice and experim ents, a new basis of research had thus been established tow ards the end of the 17th century. S tartin g out from this new basis, it became possible to fu rth e r prom ote investigations of the qualitative transform ations of substances. Y et required was, adm ittedly, the logical application of methods of quantitative exam inations in order to be able to establish definitely those fixed items th a t science was looking for, t h e ' tru e chemical elements.
