Thomson, Thomas

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b. Crieff, Scotland, 12 April 1773; d. Kilmun, Scotland, 2 July 1852)


Thomson was the seventh child and youngest son of John Thomson, a retired woolman, and Elizabeth Ewan. Having been educated mainly at home by his talented mother and by his brother James, he enjoyed a good classical training at the Burgh School of Stirling from 1786 to 1788. In 1788 he won a bursary to the local University of St. Andrews, where he studied classics, mathematics, and natural philosophy. With a medical career tentatively in mind, in 1791 he began attending a variety of classes at the University of Edinburgh, where in 1795-1796 he was inspired to devote his life to chemistry by Joseph Black’s impeccably elegant lectures. Although he did not graduate M.D. until 1799, from 1796 until 1800 he replaced his brother James as assistant editor of the Supplement to the third edition of the Encyclopaedia Britannica, to which he contributed extensive articles on chemistry and mineralogy. After 1800 Thomson devoted himself largely to chemistry as teacher, researcher, textbook writer, editor, and historian. Between 1800 and 1811 he made a precarious living as a private lecturer on chemistry in Edinburgh. During this period he published, on the basis of his articles in the Britannica, his bestselling A System of Chemistry (Edinburgh, 1802). In 1805 he acted as a well-paid consultant for the Scottish Excise Board and in 1807, with characteristic enterprise, instituted a private laboratory class in practical chemistry. In 1808, as a pugnacious opponent of Edinburgh’s Huttonian geologists, Thomson helped to found the Wernerian Natural History Society. Becoming a fellow of the Royal Society in 1811, Thomson launched himself as a historian with his unofficial History of the Royal Society (London, 1812). From 1813 to 1820 he edited, first in London (1813–1817) and then in Glasgow (1817–1820), his own journal Annals of Philosophy, which rapidly overtook its proprietary competitors. The last phase of his entrepreneurial career began in 1817, shortly after his marriage to Agnes Colquhoun, when he was unanimously elected lecturer in chemistry at the University of Glasgow. Within seven months his aggressive opportunism had elevated this post into a regius professorship, which he held until his death. Thomson worked hard to reestablish the distinguished tradition of chemistry at the university and to improve its growing medical school. Particularly during the 1830’s he was centrally involved in the unsuccessful political attempts made to elevate the status and increase the rights of the regius professors in the university. Tired by his life of unremitting effort, in 1841 Thomson relinquished part of his lecturing and the supervision of the laboratory to his nephew Robert Dundas Thomson, whom he had groomed as his successor. From 1846 until 1852 all his duties were discharged by his nephew, who subsequently failed to acquire the chair.

A self-taught chemist, Thomson first secured his reputation through the publication in 1802 of his System, which was so popular that it went through six editions during the next eighteen years: it also received the further accolade of appearing in French, German, and American editions. As the first systematic treatise of a nonelementary kind to break the French monopoly of such works, Thomson’s System tried patriotically to do justice to the contributions made by British chemists to the new chemistry, which had been established in the late eighteenth century. Unusual for British works of the time, this well-ordered and careful digest was based on a wide range of original and recent papers as well as on the standard works. Quite characteristically, Thomson tabulated numerical data and employed a style that was attractively clear, frequently succinct, and occasionally trenchant. In the third edition of his System (Edinburgh, 1807), he began a thirty years’ stint as John Dalton’s warmest advocate when he extended the latter’s chemical atomic theory from gases to include acids, bases, and salts. In January 1808 Thomson was the first to submit an experimental illustration of the law of multiple proportions, doing so at least four months before the publication of Dalton’s New System of Chemical Philosophy (1808). This paper, “On Oxalic Acid” (Philosophical Transactions, 98 [1808], 63–95), also established a useful method of determining empirical formulas. After 1808 Thomson’s enthusiasm for chemical atomism and for its mathematical harmonies burgeoned, an enthusiasm palpably displayed in the successive editions of his System, and countervailing the cautious skepticism shown by Wollaston and, more strongly, by Davy. His fervor was also apparent in his journal, Annals of Philosophy, in which he printed abstracts of currently published research by Continental as well as by British workers; inaugurated annual reports on the progress of science; and offered well-documented scientific biographies. Not unexpectedly, chemistry was the dominant subject of the journal, and its columns a leading vehicle for Dalton’s chemical atomic theory. In 1815 Thomson espoused a second and related quantitative chemical cause when he published in his journal William Prout’s anonymous paper on the specific gravities of gases. From then on Thomson focused his research upon three connected aims; to put Dalton’s theory on a wider and firmer experimental basis; to provide conclusive experimental evidence for Prout’s hypothesis that the atomic weights of elements were whole-number multiples of that of hydrogen; and to extend his projected investigation of the composition and formulas of salts to encompass those of all known minerals, particularly those containing aluminum.

During his first five or six years at Glasgow, Thomson and his laboratory students tried to accomplish the first two of these aims; their results were finally revealed in Thomson’s An Attempt to Establish the First Principles of Chemistry by Experiment (London, 1825). Doubtless Thomson felt that this ambitious work was the culmination not only of his atomic labors but also of a long and busy career. Yet his measurements of the specific gravities of gases, of which he was proud, were shown in 1825 by his friend Harry Rainy to be inaccurate. Worse still, in 1827 the reliability of his gravimetric analyses was severely assailed by Berzelius, at that time the dominant analytical chemist in Europe. His lethal conclusion that many of Thomson’s fundamental experiments were made at the writing table did not enhance the reputation of the dour Scot, although his atomic weights were widely accepted in Great Britain and in the United States between 1825 and about 1835. In 1836 Thomson completed his research program by publishing his Outlines of Mineralogy, Geology, and Mineral Analysis (London, 1836), in which he arranged minerals on the basis of their experimentally determined chemical composition and not on the basis of their physical properties. As he discovered no new elements and was working in a research field that had been already intensively developed, the work aroused little controversy or notice.

The outstanding pedagogic feature of Thomson’s professorial work was his pioneering emphasis on the laboratory teaching of practical chemistry. By the autumn of 1818 he had extracted from the university a chemical laboratory in which he established the first school of practical chemistry in a British university. He trained his students in the qualitative and quantitative analysis of inorganic substances, particularly minerals. Many of his students seem to have subsequently worked in the Glasgow chemical industry. Some of the more competent pupils were recruited by Thomson to form a small research school. By the mid-1830’s his laboratory had become a nursery from which ambitious chemists migrated to other laboratories, including that of Justus Liebig, to complete their training.

Although sometimes arrogant and perpetually sardonic, Thomson became a father figure for Glaswegian scientists during the 1830’s. His History of Chemistry (London, 1830-1831), unique and authoritative from 1760 onward, was professional propaganda that inter alia legitimated chemistry for the educated layman as a noble, rational, and autonomous science. From 1834 until his death Thomson was the president and chief ornament of the Philosophical Society of Glasgow. Indeed, in 1834 he was largely responsible for changing the moribund society dominated by artisans into an intellectually and administratively competent one that under his supervision at last began to publish its Proceedings in 1841. Not surprisingly he acted as Glasgow’s senior host to distinguished scientific visitors and eagerly supported the activities of the British Association for the Advancement of Science during its first crucial decade. The leadership that Thomson gave to Glaswegian science, like so much else that he did during his career, shows the sort of reward that could be won at that time in British science by an ambitious self-made chemist who was distinguished more for unflagging industry than for brilliant originality.


I. Original Works. Thomson’s important books are listed by J. R. Partington. A History of Chemistry, III (London, 1962), 716–721. The Catalogue of Scientific Papers Compiled by the Royal Society of London (London, 1871), 5, 970–976. lists 201 items by him.

II. Secondary Literature. The basic biographies remain R. D. Thomson, “Biographical Notice of the Late Thomas Thomson,” in Glasgow Medical Journal, 5 (1857), 69–80, 121–153, 379–380: and W. Crum, “Sketch of the Life and Labours of Dr. Thomas Thomson,” in Proceedings of the Philosophical Society of Glasgow, 3 (1855). 250–264. Further secondary sources and a discussion of his professorial career are given by J. B. Morrell, “Thomas Thomson: Professor of Chemistry and University Reformer,” in British Journal for the History of Science, 4 (1969), 245–265: and “The Chemist-Breeders: the Research Schools of Liebig and Thomas Thomson,” in Ambix, 19 (1972), 1–46.

J. B. Morrell