Cadet (or Cadet De Gassicourt or Cadet-Gassicourt), Louis-Claude

(b. Paris, France, 24 July 1731; d. Paris, 17 October 1799),

chemistry.

Cadet was the son of Claude Cadet, a surgeon at the Hôtel-Dieu in Paris who died in 1745, leaving an impoverished widow and thirteen children who were adopted by friends in various localities. Later in life members of the Cadet family appropriated the names of communities in which they had been raised. Such was the case with Louis-Claude, who had been sent to the village of Gassicourt, near Mantes-la-Jolie. Upon completion of his studies at the Collège des Quatre-Nations, Cadet served an apprenticeship in

pharmacy and chemistry at the establishment of Claude Humbert Piarron de Chamousset. He then found employment in the prestigious apothecary shop owned by Claude-Joseph Geoffroy and his son, Claude-François, both members of the Academy of Sciences.

In 1753 Cadet received a six-year appointment as apothicaire-major at the Hôtel Royal des Invalides. At the conclusion of his term at the Invalides he purchased an apothecary shop on the rue St. Honoré that achieved an excellent reputation and provided him with a good income. Cadet also served with the military outside of France, in 1761 reorganizing the pharmaceutical services of the French armies stationed in Germany. He collaborated with Berthollet and Lavoisier at the Paris mint and served as royal commissioner at the Sèvres porcelain works. Cadet was regarded by his contemporaries as a chemist of repute, as evidenced by his election to the Royal Academy of Sciences in 1766 as adjoint chimiste, with promotions to associé chimiste in 1770 and pension-naire chimiste in 1777.

Cadet’s earliest research, dating from 1755 to 1757, concerned the analysis of mineral water and was carried on initially with his teacher, Guillaume-François Rouelle. In 1757 he discovered a “fumingliquor” resulting from the distillation of arsenous oxide with potassium acetate. His discovery of this impure cacodyl substance was presented to the Academy of Sciences that same year, reported on favorably by L. C. Bourdelin and Lassone in January 1758, and published in the Academy’s Mémoires de mathémaique et de physique in 1760. Using “Cadet’s fuming liquor,” Bunsen in 1837 began his important investigation of cacodyl compounds, which led to his isolation and elucidation of the cacodyl radical.

Cadet’s attempt in 1759 to show the chemical nature of borax was unsuccessful. He did succeed, however, in developing more efficient methods for producing potassium acetate and ether. In 1774 his claim that mercuric oxide was reduced by heat to mercury was challenged by Baumé but supported by Sage, Mathurin Brisson, and Lavoisier in a report to the Academy. Particularly noteworthy among Cadet’smany investigations made jointly with his fellow academicians were those performed in 1772 to test the effect of heat on diamonds, in which he collaborated with Macquer and Lavoisier.

Influenced by the teachings of the Geoffroys and the Rouelles, Louis-Claude Cadet worked in the mainstream of pharmaceutical, mineralogical, and analytical chemistry long cultivated on the Continent. He was comfortably settled in this tradition and, unlike his colleagues Sage and Baumé, did not attack the New Chemistry, preferring to remain silent.

BIBLIOGRAPHY

I. Original Works. The bulk of Cadet’s work was published alone or in collaboration with others in Mé moiresde mathématique et de physique, présentés à l’Acadé mieroyale des sciences par divers scavans et lns dans ses assentblées; Histoire de l’Académie royale ties sciences: and in Abbé Rozier’s Observations sur la physique, sur l’histoire naturelle et sur les arts. A detailed bibliography of Cadet’spublications, comprising some fifty-two items, is given in Paul Dorveaux, “Apothicaires membres de l’Académie royale des sciences. X. Louis-Claude Cadet, dit Cadet de Gassicourt, alias Cadet-Gassicourt,” in Revue d’histoire dela pharmacie.4 , no. 88 (Dec. 1934). 385–397: 5 , no. 89 (Mar.1935). 1–13; bibliography, pp. 10–13.

II. Secondaray Literature. In addition to the Dorveaux article cited above, see also Pierre F. G. Boullay, Notice historique sur la vie et les travaux de L.-CI. Cadet-Gassicourt (Paris, 1805); Eusèbe Salverte, Notice sur la vie et les ouvrages de Louis-Claude Cadet-Gassicourt… lue a la rentrée du Lycée républican le l^er Frimaire an VIII… (Paris, 1799); L. G. Toraude, Étude scientifique, critique et anec dotique sur les Cadet, 1695–1900(Paris, n.d.), repr., rev., and enl. from Bulletin des sciences pharmacologiques, 6 “The Cadet Circle: Representatives of an Era in French Pharmacy,” in Bulletin of the History of Medicine, 40 , no. 2 (Mar,-Apr. 1966). 101–111; and J. R. Partington, A History of Chemistry, III (London-New York, 1962), 96. For Cadet’s role in the diamond experiments see Henry Guerlac, Lavoisier—The Crucial Year (Ithaca. N.Y., 1961).

Alex Berman