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ATOMS AND ALCHEMY Chymistry and the Experimental Origins of the Scientific Revolution
By William R. Newman THE UNIVERSITY OF CHICAGO PRESS Copyright © 2006 The University of Chicago
All right reserved.
ISBN: 978-0-226-57697-8
Chapter One The Mise en Scène before Sennert
I
The Medieval Tradition of Alchemical Corpuscular Theory
In 1619, a mild-mannered professor of medicine at the University of Wittenberg published a work intended to reconcile the warring opinions of chymists, Galenists, and Aristotelians. Despite its eirenic facade, however, Daniel Sennert's De chymicorum cum Aristotelicis et Galenicis consensu ac dissensu actually provided a dramatically convincing experimental demonstration that matter at the microlevel is corpuscular, thereby paving the way for the flagrantly anti-Aristotelian "mechanical philosophy" of Robert Boyle and his compatriots. All the same, regardless of its impact on Boyle and others, Sennert's demonstration was deceptively simple and relied on well-known phenomena for its power of conviction. Sennert himself derived the experiment from earlier written sources and provided little that was new in terms of empirical data. In essence, his experiment consisted of dissolving precious metals in strong acids, and then precipitating them out,seemingly unchanged, by means of alkalies. This unspectacular process of dissolution and reduction was embedded, moreover, in a diffuse discussion of the history of atomism and scholastic theories of matter. And yet, despite their seemingly mundane character, Sennert's operations provided a powerful basis for the increasingly experimental corpuscular theory of the seventeenth century. His experiment was sufficiently impressive that the young Boyle borrowed it almost verbatim in his first written treatment of atomism and used it in modified form throughout his many later attempts to justify the mechanical philosophy. Sennert himself employed the demonstration in many of his subsequent works to support his corpuscular theory, in contexts as varied as the discussion of occult qualities and the spontaneous generation of living beings. For him and for Boyle, the reduction of dissolved metals into their original or "pristine" state (reductio in pristinum statum) became a sort of crucial experiment, though Sennert himself seems to have been ignorant of the famous use that Francis Bacon made of that term.
Despite the rapid impact of Sennert's claims, his corpuscular theory stemmed from an alchemical tradition extending back in an unbroken lineage to at least the thirteenth century. The importance of this tradition, as well as Sennert's contribution, has until quite recently been largely overlooked by historians. And yet, the alchemical corpuscular theory inaugurated in the Middle Ages was of tremendous significance, for it combined the insight that matter was particulate at the microlevel with evidence for the same position acquired by means of experiment. The atomism of classical antiquity, for all its brilliance, had not originated out of an experimental context. The well-worn story of Democritus of Abdera and his teacher Leucippus reacting in the fifth century B.C.E against the monism of their Eleatic forebears is a staple of introductory philosophy courses and need not detain us here. Democritean atomism was a concession to the world of the senses, of course, but its origin lay in the Abderite's philosophical desire to undermine the world of unchanging "being" proposed by his predecessor Parmenides. Democritus's brilliant solution, as every philosophy undergraduate knows, was to admit the existence of pure being in the form of atoms, but to argue that these were separated by nonbeing in the form of void spaces. Hence motion could exist, since there were gaps into which the atoms could move, and by varying the shape and size of the atoms, Democritus could in a fashion account for the multivariate complexity of the phenomenal world.
The metaphysical origins of Democritean atomism are clear enough, even if the details of his system are lost in the haze of historical amnesia. His revivers Epicurus and Lucretius, who came at opposite ends of the Hellenistic period, made important additions to the Democritean system, but they too were strangers to the laboratory. An equally salient consideration for our story is the fact that Epicurus and his followers lived after Aristotle. Every commentator on the Stagirite's Physics, Metaphysics, and De generatione et corruptione felt obliged to explain Aristotle's famous rejection of Democritus. There was no similar compulsion for the scholastic natural philosophers to expand on the Epicureans. When Daniel Sennert became an outspoken adherent of atomism, he therefore announced himself to be a follower of the Abderite. And yet, paradoxically, Sennert was not a disciple of Democritus alone, but also of Aristotle. Indeed, his peripatetic tendencies reveal, better than almost any other source, the great variety hidden beneath the deceptive term "Aristotelianism" in the Renaissance. Until his death in 1637, Sennert remained a serious follower of Aristotle, and yet he was also a self-styled "atomist."
In order to understand Sennert's approach to atomism and the significance of his work, we must begin with the tradition of experimental and corpuscular alchemy that formed his most important source. Like Sennert himself, this tradition was highly Aristotelian in character, and yet it reflected a type of Aristotelianism that finds little or no representation in modern histories of philosophy. The peripatetic philosophy that inspired medieval alchemists was not the highly abstract, even metaphysical natural philosophy of Aristotle's Physics and De caelo but instead the more empirically oriented parts of the Stagirite's corpus, such as the Meteorology and certain portions of De generatione et corruptione. It may surprise some readers to learn that the alchemists of the High Middle Ages made a sustained attempt to conform their art to the tenets of scholastic natural philosophy and that this approach wedded them to the debate-strewn world of medieval university discourse, but this is in fact the case. Despite modern stereotypes that cast alchemy either as the epitome of unlettered empiricism, the embodiment of dishonest greed, or the vehicle of attempts to attain a mystical union with divinity, scholastic writers on alchemy in the twelfth and thirteenth centuries were concerned above all with the attempt to fit alchemy into the rationalistic edifice of Aristotelian natural philosophy. In one sense, their efforts met with limited success, since a backlash against alchemy arose in the early fourteenth century, with mainstream theological figures, including Pope John XXII, condemning the aurific art. The close connection between alchemy and important university figures of the thirteenth century, such as Albertus Magnus and Roger Bacon, found little counterpart in the fourteenth or fifteenth, and the field failed to find a home in late medieval university curricula. From another perspective, however, scholastic alchemy was a monumental success. As the present book will show, the alchemists of the High Middle Ages established an experimentally based corpuscular theory that would develop over the course of several centuries and eventually supply important components to the mechanical philosophy of the Scientific Revolution. The very movement that devoted itself single-mindedly to the destruction of Aristotelian natural philosophy was itself indebted in highly significant ways to the Aristotelianism of the Latin alchemists.
The experimental corpuscular theory of medieval and early modern Western alchemists was largely an elaboration of a textual tradition inaugurated around the end of the thirteenth century by the European author who called himself "Geber." The name "Geber" is a partial Latin transliteration of "Jabir ibn Hayyan," a semifabulous Arabic author who supposedly lived in the eighth century and spawned almost three thousand works. Yet the foundational text for our story-the Summa perfectionis (Sum of Perfection)-though dependent on Arabic models, was not a translation from Arabic but an original composition by a Latin author living around the end of the thirteenth century, probably the writer who in another work styled himself Paul of Taranto. In order to understand Sennert and later authors, we must begin with an overview of the Summa's immensely influential theory and its experimental basis. The Summa, despite the fact that it is a highly scholastic work, presents a theory of mixture at odds with the usual understanding of Aristotle. Geber describes the combination of elementary minimae partes (very small particles) or minima that come together in a fortissima compositio-a "very strong composition"-to make up the two principles of metals, sulfur and mercury. This theory is expressed very clearly in the twenty-fourth chapter.
Each of these [principles] in genere is of very strong composition and uniform substance. This is so because the particles of earth are united through the smallest particles (per minima) to the aerial, watery, and fiery particles in such a way that none of them can separate from the other during their resolution. But each is resolved with the other on account of the strong union that they mutually have received through the smallest (per minima).
Geber here asserts that the four Aristotelian elements, fire, air, water, and earth, combine "through the smallest" (per minima) to form the compounds of mercury and sulfur. He views the four elements as minute corpuscles that bind together to form larger complex corpuscles, united in a "very strong composition." The term "very strong composition" (fortissima compositio) is highly revealing, as the usual Latin word employed by the scholastics for a mixture of ingredients was mixtio or mixtura, from the Greek mixis. In order to understand the meaning of Aristotelian mixis, the contemporary reader must make a conscious effort to forget the terminology of modern chemistry, which refers to mechanical juxtapositions of particles as "mixtures" and distinguishes such uncombined ingredients from those that have entered into a "chemical compound" joined by "chemical bonds." The language employed by chemists today provides an almost exact reversal of the terminology used by Aristotle, for whom "mixture" meant a homogeneous combining of ingredients and "compound" or "composition" meant a mere juxtaposition of uncombined parts. Aristotle had claimed in his De generatione et corruptione that genuine mixis occurred only when the ingredients of mixture acted upon one another to produce a state of absolute homogeneity. Otherwise, he asserted, a sufficiently keen-sighted person, such as the classical hero Lynceus, would be able to see the heterogeneous particles that made up what had seemed to be a genuinely uniform substance. Aristotle's predecessor Empedocles had of course espoused precisely the sort of theory that Aristotle was here debunking. Empedocles had maintained a century before Aristotle that the four elements were composed at the microlevel of immutable particles, which lay side by side to form compounds (what chemists today would call "mixtures"). Aristotle argued that such corpuscles could only form an apparent mixture, like wheat and barley in a jar: he dubbed such illusory mixture synthesis-literally "setting together." The exact Latin equivalent for Aristotle's synthesis, as employed in the common medieval translations and adopted by eminent scholastics such as Albertus Magnus, was compositio, again literally "setting together" or "putting side by side."
It appears, then, that the author of the Summa perfectionis, who was himself trained in the philosophy of the schools, was implicitly erecting a theory of matter at odds with the concept of mixture laid out in Aristotle's De generatione et corruptione when he employed the expression fortissima compositio. As we will see in a later chapter, the Summa's theory was not anti-Aristotelian per se, since it derived mainly from another part of Aristotle's weighty corpus, namely, book 4 of the Stagirite's Meteorology. But for now let us consider the Summa's theory on its own terms. Geber's "very strong composition" was not a mixture at all in the strict sense of Aristotle's De generatione et corruptione but rather a corpuscular juxtaposition like that of Empedocles. Unlike Empedocles, however, Geber incorporated the key notion of compositional stages into his system: the four elements could combine to form the larger complex corpuscles of mercury and sulfur, and these in turn combined to form the corpuscles of the different metals as such. Although Geber's hierarchical stages do not map precisely onto the modern view of atoms and molecules, it is not too much to view his notion of a fortissima compositio joining discrete corpuscles as having a kinship with the chemical bond of contemporary chemistry.
The experimental basis of Geber's claim lies partly in the laboratory process of sublimation, particularly the sublimation of mercury and sulfur. Although he views these two substances as principles of the metals, they do not acquire the hypothetical quality in the Summa that they often do in early modern alchemy. When Geber speaks of sulfur and mercury here, he means common brimstone and quicksilver-the sulfur and mercury of the modern periodic table. Geber's claim for the corpuscular nature of these substances is based on two observational facts. First, the sublimed mercury and sulfur collect in the "aludel" or sublimatory vessel as tiny droplets (mercury) or minutely divided powder ("flowers" of sulfur)-hence the process of sublimation seems to reveal their particulate structure to the naked eye. Second, and more important, these two substances can be sublimed intact such that they leave little or no residue in the bottom of the aludel. This is the point of Geber's comment that mercury and sulfur are "resolved"-here meaning "sublimed"-without decomposing into their elementary components. As he says at another point in the Summa, "We see a manifest example (experientia) of this in the sublimation of spirits. For when a sudden resolution comes about in them by means of sublimation, the humid is not separated from the dry, nor the dry from the humid so that they be divided into the parts of their mixture." Geber elaborates on this point later in the text, observing that sulfur "has a very strong composition, and is likewise uniform and homoeomerous in its particles, because it is homogeneous. Thus its oil is not borne away from it by distillation, as it is from other things having oil." This resistance of sulfur and mercury to the analytical power of heat is largely due to the "very strong composition" (fortissima compositio) by which their elementary corpuscles are conjoined. It cannot be overstressed that Geber's claims about the substantial integrity of mercury and sulfur are based on the fact that these materials resist analysis when subjected to laboratory operations such as sublimation. Geber's reliance on a laboratory process to determine the practical limits of analysis and, hence, to establish the constituents of other bodies by means of experiment would have profound resonances in the later history of chemistry. We will consider this important point more deeply later.
While focusing on the "very strong composition" of the principles, the Summa also refers to another factor responsible for their durability-their uniformis substantia (uniform substance). What precisely does he mean by this uniform substance? Aristotle had famously argued in De generatione et corruptione (328b 22) that the ingredients of a mixture undergo a henosis or unification during the process of being mixed. Hence all the spatial regions of a true Aristotelian mixture are "homoeomerous"- identical in all their parts (De gen. et corr. 328a 10-12). Obviously, the type of unification envisioned in De generatione et corruptione is excluded by the Summa's compositional matter theory. Nonetheless, the Summa refers to sulfur as being "homoeomerous in its particles, because it is homogeneous," and the term "homoeomerous" is employed earlier in the text to describe the principles:
A true mixture of the dry and humid so that the humid be tempered by the dry and the dry by the humid, and so that this become one substance homoeomerous in all its parts, and temperate between hard and soft, and extensible in contusion, does not occur except by continual mixture of the viscous humid and the subtle earthy through the smallest particles (per minima).
(Continues...)
Excerpted from ATOMS AND ALCHEMY by William R. Newman Copyright © 2006 by The University of Chicago. Excerpted by permission.
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