ANTECEDENTS TO THE BOYLE CONCEPT OF THE ELEMENT1*" AARON 1. IHDE University of Wisconsin, Madison, Wisconsin
D U R I N G the present century the definition of the element has become stabilized to mean a substance whose atoms all have the same atomic number. I n order t o arrive a t this kind of a precise definition it was necessary for chemists not only to he willing to accept an atomic theory of matter, but also to deduce sufficient information about the nature of atoms as to realize the physical validity of atomic numbers. Prior to the recognition of atomic numbers, chemists had found it necessary to content themselves with a more crude operational definition, brought into popularity by Lavoisier, and based upon chemical analysis. During this period the element was any substance which could not be further simplified by chemical operations. The imprecise nature of this working definition is revealed by the numerous changes in the list of elements which took place from the publication of Lavoisier's "Trait6 E16mentaire de Chimie" in 1789 up to the beginning of the present century. The list in the "Trait6" contained 33 "elements," including light and caloric (heat). Lavoisier held some reservations regarding the elemental nature of some of these substances, and rightly so, for our present list of elements carries only 24 of those in Lavoisier's list. To his credit it must be pointed out that seven of the deletions represent compounds like magnesia, alumina, and the "radical boracique" which subsequently yielded new elements. The uncertainty regarding the assignment of elemental status to a substance, which plagued chemists throughout the next century, is revealed repeatedly in the announced discovery of pseudo-elements. The "uranium" announced in 1789 by Klaproth3was shown by Peligot4 a half century later to be an oxide. The numerous uncertainties in the unraveling of the rare earth elements further illustrate the problems? Despite these difficulties, the serious use of such a concept was a boon t o the development of chemistry. The concept of elements placed into operational application by Lavoisier actually had been known for more than a century and is commonly associated with
Presented before the Division of History of Chemistry st the 129th Meeting of the American Chemical Society, Dallas, April, 1956. .....
%Thisstudy wss supported by a summer research appointment made possible by funds from the DuPont grant-in-aid to the University of Wisconsin chemistry department. a KLAPROTH, M. H., Cell's Chem. Ann., 12,387 (1789). ' PELIOOT,E., Compt. rend., 13, 417 (1841). "WEEKS, M. E., "Di8~0very of the Elements," 5th ed., J. CHEM.EDUC., Eastan, Pennsylvania, 1945, pp. 41k35. 5
Boyle. I n his "Sceptical Chymist," Boyle attributed to his spokesman, Carneades, the statement: And, to prevent mistakes, I must advertise you, that I now mean by elements, as those chymists that speak plainest do by their principles, certain primitive and simple, or perfectly unmingled bodies; which not being made of any other bodies, or of one another, are the ingredients of which all those called perfectly mixt bodies are immediately wmpounded, and into which they are ultimately resolved.
The statement actually had little influence in Boyle's own time or in the decades immediately following, but a century later it formed the point of departure for Lavoisier and his followers in laying the foundations of chemistry.' It is even doubtful that Boyle believed in the existence of the kind of elements thus defined, for the statement of Carneades continues: Now whether there be any such body to be constantly met with in all, and each, of those that are said to be elemented bodies, is the thing I now question.
There is, however, no doubt that there were chemists who accepted the existence of such elements in his time and earlier.8 Boyle's purpose in the book was to question the elemental nature, within Carneades' definition, of the commonly accepted elements of the Aristotelians (fire, air, water, earth) and of the Paracelsians (sulfur, mercury, salt). He was unwilling to decide that any known substance was clearly elemental and nowhere in the book, or in his many other works, did he clearly suggest any substance that should be considered an element. I n fact, he always went to great pains to disprove the elemental nature of well-known substances, as is the case in his very rare book, "An Historical Account of the Degradation of G ~ l d , "where ~ he allegedly BOYLE,R., "The Sceptical Chymist," printed by J. Caldwell for J . Crooke, London, 1661, p. 350. Since there have been a number of erroneous statements to the effect that the definition did not appear until publication of the second edition of 1679/80 it is perhaps in order to emphasize the identical warding in bath first and second editions (p. 354). The widely available Everyman's Library reprint of the second edition has the statement a n page 187. ' DAVIS, T. L., Isis, 16,82 (1931). 8 Note the part of the definition which reads, "as those chymists that speak plainest do by their principles. . . . " This part ) when of the quatatition has frequently been replaced by (. quoted, thus contributing to the common belief that this concept of elements was original with Boyle. BOYLE, "An Historical Account of the Degradation of Gold,"printed by H. N. for Henry Herringmen, London, 1678, 17 pp. See S. A. IVES AND A. J. IKDE, J. CHEM.EDUC., 29, 244 (1952). Also in "The Sceptical Chymist," Everyman's Edition, p. 215 f., Boyle alludes to the degradation of gold.
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succeeded in obtaining silver from gold. It has been seventeenth century. This development is connected shown by Kuhnlo that Boyle was unwilling to accept with a growing skepticism regarding (1) the role of the any substance as elemental other than a prima materia. four elements in explaining the nature of the universe, This study of Kuhn and recent studies of Boasl1have and (2) the possibility of transmuting one metal to anshown that while Boyle's interests were primarily other. chemical, his thought was dominated by the advances in physics taking place in the seventeenth century. Like CHANGING COSMOLOGIES Newton, he hoped to explain chemical phenomena in Ancient and medieval systems of the universe folterms of mechanical behavior. A corpuscular or atomic lowed Aristotle in utilizing the four elements along with philosophy lent itself to this sort of approach, and Boyle a perfect fifth element, the quintessence. Earth, considconvinced himself that differences in properties might ered absolutely heavy, formed the sphere of earth at the be explainable in terms of relative motions of corpuscles center of the universe. This was surrounded in turn rather than in terms of innate differences in the sub- by the sphere of water (the relativelyheavy element), the stances themselves. I n this way it would be possible to sphere of air (relatively light), and fire (absolutely succeed with a single primary matter, and Boyle appar- light). Beyond the sphere of fire came the spheres of the ently saw no need to include others. moon and the other planets, all made up of the quintesIt has been clearly established that Boyle was a cor- sence. Since the quintessence was a perfect element, puscular philosopher. That he was familiar with the changes could not take place beyond the sphere of fire. atomic ideas of such predecessors as Van Helmont and Philosophers, of course, encountered the troublesome Seuuert is shown by repeated references to them in "The fact that the sphere of earth was not perfectly surSceptical Chymist." Their thoughts in turn were based rounded by that of water. This had necessitated adupon atomic speculations harking back ultimately to justments in the medieval cosmology, suggesting that it the Epicureans. Atomism, while not popular in the was necessary for the sphere of earth to extend through middle ages, was nevertheless discussed in the works of the sphere of water in prder to provide a home for man. Isadore of Sevelle (56&636), the Venerable Bede This might be explained if, instead of the spheres being (672-735), Hrabanus Maurus (776-856), Al-Razi (d. concentric, they were eccentric. I n this way one side ca. 924), and Maimonides (1135-1204).'2 William of of the earthly sphere might be exposed sufficiently to Conches (1080-1154) openly taught the atomic ideas provide for man's needs while the other side was deeply of Democritus and Epicurus. Lucretius' great poem, submerged. The voyages of exploration in the fifteenth "De rerum natura," existed in manuscript in several and sixteenth centuries revealed, however, that land Western libraries and was known to Nicolas of Cusa. masses were to he found exposed on the other side of It was printed in 1473 and again in 1486, hence was one the globe, hence the satisfying sphere hypothesis was of the ancient Latin works to attract the attention of becoming untenable. A new blow was suffered in 1572 when a nova flared the Renaissance humanists. As such it helped to plant the ideas which were to figure so prominently in the sev- forth in the constellation Cassiopoeia, attracting the enteenth century reaction against Aristotle. Fracas- attention of Tycho Brahe and other astronomers. Very toro, Ramus, and Bruno reflected these ideas in the six- soon it was shown to be more distant than the lunar teenth century. Their primitive and speculative seeds, sphere. It had burst into brilliance, not in the sphere minima, and corpuscles gained adherents in the next of fire, but in the quintessence! Another blow occentury, adherents such as Gassendi, Sennert, Van curred in 1577 when a brilliant comet also proved to be Goorle, Basso, Sperling, Jungius, and Charleton. The beyond the limits of the sphere of fire. Such men as Peter Ramus, Jerome Cardan, and Tyatomic speculations of these men laid a background which directly and indirectly influenced Boyle and cho Bwhe found it necessary to reject fire as an element, Newton in their corpuscular philosophies. simultaneously discarding the sphere of fire between The influence of atomic ideas on Boyle in the develop- those of the air and the moon. Jean Pena even denied ment of his attitude toward elements has been ade- the existence of the celestial spheres and went so far quately examined elsewhereI3 and there is no need to as to suggest that the sphere of air extended outward to pursue it further. There is, however, a related and the fixed stars, thus even eliminating the fifth element.14 Although chemical elements appear to have little somewhat parallel development of ideas which had an t,orln.v. -it, influence on the rise of the concent of the element in the relationshio to the motions in the heavens ----..... must be remembered that this was not true during the lo KUEN,T. S., Isis, 43, 12 (1952). Renaissance. A system of elements was an integral " BOAS.MARIE,Isis. 41.261 (1950): Osiris. 10,412 (1952) part of the traditional system of the heavens. Thus, ~ n s s = ~ zK:, , "~esohicht' der ~ t o m i & i k"on ~ittelalter bis Newtan," Verlag van Leopold Voss, Hamburg and Leipzig, when the Ptolemaic system collapsed in the seventeenth 2 vol~.,1890, Val. 1, passim. S. PINES,"Beitragesur Islamischen century it was natural that the concept of the ancient Atamslehre," Heine, Grifenhainichen, Germany, 1936. elements would likewise lose some of its authority and " K u a ~ loc. , cit. BOAS,1oc. Cit. A. G. VAN MELSEN,"From become the subject of attack. ~
~~~
~
d 7
Atamos to Atom: The History of the Concept A t a , " trans lated by H. J. Koren, Duquesne University Press, Pittsburgh, "TRORNDIKE, L., "History of Magic and Experimental 1952, Part 1. G. B. STONES, Isis, 19,444 (1928). R. HOOYKAS, Science," Columbia University Press, New York, 6 vols., 1923C h M a , 2,65 (1949). 41, Val. 6,pp. 83,351.
JOURNAL OF CHEMICAL EDUCATION DOUBTS ABOUT TRANSMUTATION
Alchemy was held in distaste by many churchmen, intellectuals, and princes throughout much of its history, but generally on account of the fraud and deceit connected with it rather than for any intellectual doubts regarding its goal. Despite the general acceptance of the possibility of transmutation, there were a few who spoke out against it because of a disbelief in the possibility of changing metals from one species to another. An early doubter was the Arab physician, Ibn Sina, known to the Latin world as Avicenna. I n his "Kitab alShifaV (Book of the Remedy) he dealt with various aspects of medicine, including chemistry. The chemical portion of the work was translated into Latin late in the twelfth century by Alfred of Sareshel as "De mineralibus" or "De congelatione et conglutinatione lapidum." It somehow became appended to the Latin translation of Aristotle's "Meteorologica" and came to be accepted as a work of Aristotle. I l ~ l m y a r d has ' ~ demonstrated that the work truly derives from the "Shifa." Ibn Sina's early writings are indicative of a belief in alchemy, but he evidently became skeptical with age. In the ''Kitab al-Shifa," which is a product of his later years, he said:16 As to the claims of the alchemists, it must be clearly understood that it is not in their power to bring about any true change of species. They can, however, produce excellent imitations, dyeing the red [metal] white 80 that it closely resembles silver, or dyeing it yellow so that it closely resembles gold. . . . Yet in these [dyed metals] the essential nature remains unchanged; they me merely so dominated by induced qualities that errors may be made ooncerning them, just as it happens that men are deceived by salt, qalqand, sal-amoniac, etc.
Two centuries later Albertus Magnus was writing in There are numerous alchemical works ascribed to this author, most of them fabrications of a later period. Hence, his real position is beclouded by writers who merely used his name t o gain acceptance for their own views. Albert's real position on chemistry is seen in "De mineralibus," a work about whose authorship there is no question. In this work Albert considered metals to be distinct species without being entirely clear as to their relation to sulfur and mercury. He appears to have held the current concept that metals represented a combination in some fashion of these fundamental substances. However, he argued that merely coloring metals did not make true gold or silver. Since this is what was done by alchemists their gold, he said, did not stand the test of fire for more than five or six times." I n the sixteenth centurv there ameared a number of a somewhat similar vein.
~ H o ~ m J., ~ mAND , D . C. MANDEVILLE, "Avioennae de congelittione et conglutinatione lapidum," being seotions of the Kitab al-Shifa. The Latin and Arabic Texts edited with an English translation of the latter and with critical notes, Geuther, Paris, 1927. " Ibid.,p. 41. '7 ALBERTUS MAGNUS,"De mineralibus," 111, i, 8. From A. BORGNET, Editor, "B. Alberti Magni Opera Omnia," V. Vives, Paris, 33 vols., 1890-99, Vol. 5, pp. 69-70.
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works dealing with mining and metallllurgy. These hooks, dealing with a practical subject, were important in laying the solid foundations of chemistry,'a and reflect the thinking of practical men on the nature and behavior of metals. None of these books show the speculation characteristic of strictly alchemical works hut deal largely with operations. The authors scarcely touch upon alchemical matters, but when they do their opinion is one of disinterest bordering on skepticism. Biringuc~io,'~ in particular, questions the ability of alchemists to achieve the production of gold though it is apparent that he holds the Aristotelian idea that perfection of metals takes place in nature. Agricola20and ErckerZ1also showed skepticism respecting the ability of the alchemists to achieve their goals. Another technologist who took a dim view of transmutation was Palissy, the French potter. He claimed that by cupellation it was easy to show that alchemical silver and gold were false. A minor figure whose views are of interest is Symphorien Champier (ca. 1471-1537), a physician of Lorraine who wrote numerous popular works on a wide variety of subjects. Although he was of only secondary ability, he rose to considerable importance in his day as the result of shrewdness in attaching himself to iufluential persons who might help him in his desire for fame. I n keeping with the times he was well versed in the art of self-aggrandizement, or as so aptly put by T h ~ r n d i k e , ~ ~ " . . . he was full of the 'spirit of the Renaissance,' that rare gas which the historical laboratory has never yet succeeded in holding in solution." His extensive treatises on all sorts of subjects were shallow in treatment and, according to critics, shamelessly plagiarized. Surprisingly, he was an outspoken opponent of the occult arts and of alchemy. His attack on the alchemists is contained in a letter printed in 1533 along with a work defending the Greek physicians against errors of the Arabs.23 I n this letter Champier discussed the arguments for transmutation and opinions on the formation of metals, expressing as his own opinion that God created metals in their common form from which they did not deviate. I n arguing against the common theory that metals were generated from sulfur and mercury he pointed out that the rich silver mines of Lorraine contained no mercury, hence generation from mercury was not possible. His contempt for ordinary alchemists was revealed when "he repeats a statement already made in his life of Arnald of Villanova that tbe founders of Alchemy were an Arabic IHDE,A. J., J. CHEM.EDUC.,33,109 (1956). Snmq C. S., AND M. T. GNUDI,"The Piroteehnia of Vannoceio Biringuccio Translated from the Italian," American Institute of Mining and Metallurgical Engineers, New York, 1942, pp. 37-44. " HOOVER,H. C., AND L. H. HOOVER,"Geo~giusAgricola De Re Metdlillios," translated from the first Latin edition of 1556, Dover, New York, 1950, p. xxviii. SISCO,A. G., AND C. S. SMITH, "Lazarus Eroker's Treatise on Ores and Asmying, Translated from the German edition of 1580," University of Chicago Press, Chicago, 1951, pp. 189-90. sP THORNDIKE, o p . cit., Vol. 5, p. 113. '"bid,, p. 125.
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Hermes, not the ancient Hermes Trismegistus, and a most inept barbarian of putrid brain called Geher, and that the stories told of Arnald and John of Rupescissa are false and full of fables."24 The intemperate nature of Champier's remarks reminds us a t once of his contemporary, Paracelsus, whose opinions had far more influence. As is usual in Paracelsus, we find him both making changes and defending the status quo. The traditional four elements appear not to have been openly rejected by Paracelsus but he superimposed on them his three elements or principlesmercury, sulfur, and salt. There was here a system based upon the mercury-sulfur theory of metal formation long held by the alchemists but modified to be in accord with a philosophy of fire through the addition of salt, a substance inert toward fire. This set of principles played a prominent role in the theories of the "spagyrists," as the Paracelsian followers were called. These three principles, like the four elements, did not preclude the possibility of transmutation. Paracelsus considered transmutation possible as did many of his followers. The anti-Paracelsians, who attacked chemical medicine so vehemently during the next century, appear to have disliked not only his medical ideas hut also his ideas in general. Several of them, in their refutation of Paracelsian medicine, even attacked such a well-established idea as transmutation. Thomas Leiber (Erastus), the Swiss physician and religious reformer, in his "Disputations concerning the new medicine of Paracelsus" (1572) vigorously attacked the three elements, holding accursed the comparison with the holy Trinity. He considered transmutation to be i m p o ~ s i b l e . ~ ~ A rather curious attack occurred early in the next century when the Parisian physician, Nicholas Guibert, somewhat ignorantly attacked the whole corpus of alchemical literature. He claimed, in 1603, that he had pursued the subject for 40 years, finally coming to the conclusion that metals are species which cannot be transmuted. He was answered a year later by Libavius, in a "Defense of Transmutatory Alchemy." Despite the enlightened position shown toward chemistry in his famed "Alchymia" (1597), Libavius could still believe in transmutation ardently enough to defend it. Guibert was aroused t o reply with an "Apology against the Sophist Lihavius, Raging Caluminiator of Alchymia Refutata." This was later printed in 1614 with Guibert's "Destruction of Alchemy." This last work utilized the Bible and classical literature as authority for the refutation of transmutation, ending with the conclusion that any apparent successes were due to demon aid.2E A somewhat more mature attack on transmutation was made by Jean Riolan, a Parisian physician with strong anti-Paracelsian leanings. He was a leader among the defenders of Galenic medicine against the
" Ibid., pp. 12&6.
Ibid., pp. 658-9.
" Ibid., Val. 6 , pp. 2 4 - 4 5 ,
iatrochemical enthusiasm of such physicians as Duchesne (Quercetanus) and Turquet de Mayerne. A complicated series of polemical works re~ulted.~'I n an anonymous tract, ascribed to Riolan by Libavius, it was argued that the world managed without chemical medicines in the days of Hippocrates and Galen, hence the old tested remedies mere safer than remedies containing antimony, mercury, and gold. Since medicine with its four humors was closely allied philosophically with the four qualitieswet and dry, hot and cold-it was never out of place for physicians t o speculate on elements. Riolan denied the possibility of transmutation, declaring each metal to be perfect in its own species, rather than being an imperfect form of gold. The seventeenth century saw the early development of a fundamental interest in the reactions of metals in the minds of such figures as Sala, Sennert, and Van Helmont. Sala attempted to demonstrate that the production of copper by the addition of iron to blue vitriol was not a transmutation, as had been believed by Paracelsus, Lihavius, and others, but due t o the presence of copper in the vitriol. Sennert and Van Helmont both held similar views with respect to this reaction. Sennert also showed that gold might be recovered from acids in which it had been dissolved, suggesting that this was due to atoms which retained their individuality during, the solution process. Van Helmont rejected the three elements of Paracelsus and also the four elements of the Aristotelians, thus paving the way for Boyle who went to greater pains to demonstrate their nonexistence. CONCLUSION
It is apparent that a variety of developments were converging during the seventeenth century to undermine the stability of the traditional elements and pave the way for a new concept which might form an operational basis for chemical thought and experimentation. The crumbling Ptolemaic system dragged down with it the Aristotelian system of elements. Since they no longer filled a need in cosmology their value in terrestrial science also suffered. While this cannot he demonstrated to have been a positive effect, it must still have been a factor in weakening the position of these elements. Skepticism toward transmutation developed in part because of the continuous failures of the alchemists, in part because of the persistence of certain metallic species through a variety of chemical changes. Thus, as knowledge of empirical chemistry increased with the centuries, it began t o be recognized that certain substances which disappeared during the action of strong solvents such as mineral acids were not permanently destroyed or transmuted but were recoverable intact as the result of appropriate treatment. This, together with the rise of an atomic philosophy, paved the way for the development of the concept in which the element remained a fixed entity throughout chemical changes.
" For details see ibid., pp. 247-52.
