Alchemy vs Chemistry: The Transition to Modern Science

In 1789, Antoine-Laurent Lavoisier published the Traité Élémentaire de Chimie, and on the second page he drew a line. The new chemistry, he said, would deal in elements, in the modern sense — substances that could not be further decomposed by the methods of analysis. The traité would have nothing to do with the alchemists’ four elements of earth, water, air, and fire, nothing to do with the tria prima of mercury, sulfur, and salt, and nothing to do with the alchemical project of transmutation. The old framework was to be discarded. The new framework was to be built on quantitative experiment, on the oxygen chemistry of combustion, and on the systematic naming of substances. The alchemists, Lavoisier implied, had been doing something different. They were not chemists. They were something else.

That line held for about 150 years. Then, in the second half of the twentieth century, historians of science began to erase it. Lawrence Principe, William Newman, Pamela Smith, and a generation of scholars showed that the line Lavoisier drew was not really a line at all. The alchemists had developed the apparatus, the techniques, the reagents, and the empirical knowledge that Lavoisier inherited. The “Sceptical Chymist” of 1661, Robert Boyle, was an alchemist in private. The “last of the magicians,” Isaac Newton, spent more time on alchemy than on any other branch of his natural philosophy. The transition from alchemy to modern chemistry was not a replacement. It was a much more interesting process of selection, rejection, and inheritance, and the inheritance is at least as important as the rejection.

The shared origin: a continuous laboratory

The alchemical and modern chemical traditions share a continuous laboratory lineage. The Egyptian metalworkers and dyers of the Hellenistic period, the Greek alchemists of Alexandria, the Arabic alchemists of Baghdad and Córdoba, the Latin alchemists of the medieval and early modern period — all of them worked in laboratories that were the direct ancestors of the modern chemical laboratory. The apparatus, the techniques, the materials, and the empirical observations of the alchemists were the foundations on which the modern chemical tradition was built.

The apparatus of the alchemical laboratory is the apparatus of the modern laboratory in a recognisably direct line. The alembic (the domed distillation head with the long beak for the condensate), the retort (the long-necked flask for distillation under reduced pressure), the athanor (the self-feeding furnace that could maintain a constant temperature for weeks), the pelican (the reflux distillation vessel), the cucurbit (the gourd-shaped distillation vessel), the water bath (Maria the Jewess’s invention, the balneum Mariae), the sand bath — every one of these is an alchemical device, and every one of them is the direct ancestor of a piece of modern laboratory apparatus. The modern chemist who sets up a reflux distillation is performing an operation that the alchemists developed in the ninth or tenth century.

The operations are the same. Calcination (the heating of a substance to drive off volatile components and leave an oxide). Dissolution. Distillation (in all its forms — simple, fractional, steam, vacuum). Sublimation. Coagulation. Crystallisation. Filtration. The alchemists developed these operations over more than two thousand years of laboratory work, and they remained the standard operations of the chemical laboratory until the nineteenth century.

The materials are the same. The alchemists prepared and studied sulfuric acid, nitric acid, hydrochloric acid, aqua regia, mercury compounds, antimony compounds, lead compounds, copper compounds, and a long list of other substances. Many of the most important reagents of the modern laboratory were first prepared and studied by alchemists. The alchemists knew what these substances did, even when their theoretical explanation of why was wrong.

The empirical observations are the same. The alchemists knew how to prepare and purify a wide range of metals, acids, salts, and mineral preparations. They knew what happens when you heat substances, what dissolves in what, what crystallises and what does not. This body of empirical knowledge underwrites the modern chemical tradition.

The philosophical differences: qualitative versus quantitative

The alchemists and the modern chemists differed in fundamental ways about the nature of matter and the proper method of studying it, and the differences are disagreements about the basic framework within which the study of matter should be conducted.

The alchemists worked within a qualitative framework. They classified substances by their qualities (hot, cold, wet, dry; fixed, volatile, combustible; spirit, soul, body) and they explained the behaviour of substances by the balance of the qualities. The four elements of Aristotle and the tria prima of Jabir were the basic constituents of matter, and the differences among substances were differences in the proportions of the constituents. The alchemical theory was a qualitative theory, and the alchemists had no way of measuring the proportions of the constituents in a quantitative sense. They could weigh substances, but they had no instruments for measuring the weights of atoms or the proportions of elements in a compound.

The modern chemists worked within a quantitative framework. They classified substances by their composition, measured in terms of the proportions of the elements they contained, and they explained the behaviour of substances by the atomic structure of the elements. Dalton’s atomic theory (1808), Avogadro’s molecular hypothesis (1811), Cannizzaro’s reconciliation of atomic and molecular weights (1860), and Mendeleev’s periodic table (1869) were the basic frameworks of the modern chemical tradition, supported by instruments (the balance, the burette, the spectrometer) and methods (titration, gravimetric analysis, spectroscopy).

The alchemists and the modern chemists also differed about the goals of the study of matter. The alchemists aimed at the transmutation of base metals into gold, the preparation of the elixir of life, and the integration of the human being with the cosmos. The modern chemists aimed at the understanding of the composition and behaviour of matter for its own sake, and at the practical application of the understanding for the benefit of human life. The two sets of goals are not the same, and the alchemists’ goals were abandoned by the modern chemical tradition.

The rejection of the alchemical framework

The modern chemical tradition emerged through a series of explicit rejections of the alchemical framework. The most important of the rejections are landmarks in the history of chemistry.

Robert Boyle’s Sceptical Chymist (1661) argued that the tria prima and the four elements are inadequate theories of matter, and that chemistry should be based on the careful analysis of substances into their components. Boyle himself, despite the title of the book, remained an alchemist in private. Principe (2013, pp. 145–152) and Newman & Principe (2002, ch. 2) are the right places to read about the public/private split. The split is one of the most important pieces of evidence for the intertwined rather than sequential reading of the transition.

The phlogiston theory of Johann Joachim Becher and Georg Ernst Stahl (early eighteenth century) is a more interesting case than the older textbooks allow. Phlogiston theory was a post-alchemical, corpuscular-mechanist framework. It treated phlogiston as a material substance released in combustion and explained calcination, smelting, and respiration in corpuscular terms. Phlogiston theory is, properly, an early modern chemistry rather than a continuation of the alchemical elemental theory. It belongs to the seventeenth-century mechanical philosophy, not to the alchemical tradition, and Lavoisier’s oxygen chemistry displaced it on empirical grounds — careful quantitative experiments with combustion, the demonstration that metals gain weight when they calcine (which phlogiston theory struggled to accommodate), and the development of a new system of elements.

Lavoisier’s Traité Élémentaire de Chimie (1789) is the document that drew the line most clearly. Lavoisier redefined chemistry as the science of elements in the modern sense, named the elements systematically (the system of nomenclature that Lavoisier developed with Guyton de Morveau, Berthollet, and Fourcroy), and explicitly excluded transmutational aims. The Traité is, in a real sense, the founding document of modern chemistry, and it is also the document that draws the sharpest boundary against the alchemical inheritance.

John Dalton’s atomic theory (1808) provided the theoretical foundation for the modern chemical tradition, and Mendeleev’s periodic table (1869) organised the elements by their atomic weights and revealed the regular patterns of chemical behaviour. The periodic table is the central icon of the modern chemical tradition, and it is the definitive refutation of the alchemical theory of the four elements. The alchemists had four (or three, or five, depending on the framework). The modern chemists have more than a hundred, organised by atomic number into a structure that has no analog in the alchemical framework.

The rejection was not a single event. It was a long process that took more than two centuries. The alchemists’ claims about transmutation, the elixir of life, and the integration of the human being with the cosmos were gradually abandoned. But the rejection was selective. The alchemists’ apparatus, techniques, reagents, and empirical observations were kept. The rejection was of the alchemical theory of matter and the alchemical project of transmutation, not of the alchemical laboratory tradition.

The continuity of the laboratory

The modern chemists built on the alchemical laboratory tradition, and they used the apparatus, the techniques, and the empirical knowledge of the alchemists as the foundation of their work.

The continuity is most visible in the apparatus. The alembic, the retort, the athanor, the pelican, the cucurbit — all of these alchemical devices survived into the modern chemical laboratory, and the modern devices (the distillation apparatus, the reflux apparatus, the Soxhlet extractor, the rotary evaporator) are direct descendants of the alchemical originals. The chemist who uses a retort is using a word the alchemists coined, and the chemist who uses an alembic is using a piece of apparatus the alchemists invented.

The continuity is visible in the materials. Sulfuric acid, nitric acid, hydrochloric acid, sodium carbonate, copper sulfate, mercury — all of these substances were first prepared and studied by the alchemists, and the alchemists’ empirical knowledge of these substances is part of the working knowledge of the modern chemist.

The continuity is visible in the vocabulary. The alchemical language of the “fixed,” the “volatile,” the “spirit,” and the “body” survives in the modern chemical vocabulary of “refractory,” “volatile,” “spirit” (as in “methylated spirits”), and “body.” The alchemical language of “affinity” survived into the modern chemical concept of chemical affinity (the predecessor of the modern concept of free energy). The alchemical language of “precipitation” and “solution” survived unchanged. The continuity is in the words, and the words are the way the working chemist thinks.

The reassessment of the alchemical contribution

The modern reassessment of the alchemical contribution to the chemical tradition began in the twentieth century, particularly with the recovery of Newton’s alchemical papers in 1936 and the subsequent publication of the Boyle correspondence and the Locke alchemical manuscripts. The recovery showed that the most rigorous natural philosophers of the early Enlightenment were serious alchemists.

The reassessment has several components. The alchemical contribution to the development of laboratory techniques, apparatus, and experimental methods has been recognised. The alchemical contribution to the development of chemical substances has been recognised — many of the most important chemical substances were first prepared and studied by alchemists. The alchemical contribution to the development of chemical theory has been recognised, though in a more qualified way: the alchemists’ theory of the four elements and the tria prima was wrong in its details, but the alchemists’ conviction that matter is composed of a small number of basic constituents remains a foundational idea.

The reassessment has not rehabilitated the alchemical project. The alchemists were wrong about the possibility of transmutation, wrong about the preparation of the elixir of life, and wrong about the integration of the human being with the cosmos through the alchemical work. The reassessment has shown that the alchemists made a substantial and lasting contribution to the development of modern chemistry, and that the alchemical tradition is an essential part of the history of the chemical sciences.

The reassessment has also been marked by sharp scholarly debate. The position associated with Holmyard (Alchemy, 1957) tended to portray the alchemists as proto-scientists whose work prefigured modern chemistry. Principe and Newman have pushed back against this whiggish reading, arguing that the alchemists had their own coherent intellectual framework and that it is anachronistic to read them as failed chemists. Newman (Promethean Ambitions, 2004) and Principe (2013) are the central voices, and the position that has emerged is the intertwined one.

The Smith–Panter debate of the 1990s and 2000s is a separate but related dispute. Pamela Smith’s The Business of Alchemy (1994) emphasised the dense economic and craft networks that sustained alchemical practice, shifting the field by treating alchemy as a working business. Critics challenged some of Smith’s sociological generalisations, and the debate produced a more refined picture of the alchemical tradition. The refined picture is, I think, closer to the truth than either the old mystical reading or the old disreputable reading.

The alchemists as the first chemists

The characterisation of the alchemists as the first chemists is partly accurate and partly misleading. The alchemists were not chemists in the modern sense; they did not work within the modern theoretical framework, and they did not aim at the modern goals of the chemical tradition. But the alchemists were the first to develop a sustained, systematic, laboratory-based study of the behaviour of matter, and the modern chemical tradition descends directly from their work. The characterisation is a corrective to the older view of the alchemists as mystics and charlatans, but it should not be taken to imply that the alchemists were modern chemists in disguise. They were working within a different theoretical framework, with different goals, and with a different conception of the relationship between the study of matter and the broader questions of human life.

The correct reading, I think, is the intertwined one. The alchemists and the modern chemists share a laboratory tradition, a set of techniques, a body of empirical knowledge, and a conviction that matter is composed of basic constituents whose proportions determine the character of substances. They differ on what those constituents are, on how to measure their proportions, and on what the work is for. The shared inheritance is large. The disagreement is real. The transition is the most interesting chapter in the history of chemistry.

FAQ

Q: Was phlogiston an alchemical theory? A: No. Phlogiston theory (Becher, Stahl) was a post-alchemical, corpuscular-mechanist framework. It belongs to the seventeenth-century mechanical philosophy, not to the alchemical elemental theory.

Q: Did Boyle reject alchemy? A: Publicly, the Sceptical Chymist (1661) attacks the tria prima and the four elements. Privately, Boyle left a substantial alchemical manuscript corpus and continued to work on transmutation throughout his life. The public/private split is one of the puzzles Principe (2013) addresses.

Q: Is the “alchemy → chemistry” story one of progress? A: The old whiggish narrative (Holmyard, 1957) presented it that way. The current scholarship (Newman, Principe) treats the relationship as intertwined and overlapping rather than sequential: the same practitioners often worked in both modes.

Q: What is the Smith–Panter debate? A: A debate in the 1990s and 2000s over how to read alchemical patronage and practice: Pamela Smith (The Business of Alchemy, 1994) emphasised the dense economic and craft networks that sustained alchemical practice, while critics challenged some of her sociological generalisations.