Geoffroy, Claude Joseph

(b. Paris, France, 8 August 1685; d. Paris, 9 March 1752)

chemistry, botany.

Geoffroy the Younger (le Cadet) was the second son of Matthieu François Geoffroy and Louise de Vaux, and the brother of Étienne François Geoffroy. He qualified as an apothecary in 1703 and took over the family pharmacy on his father’s death in 1708. Highly esteemed in his profession, he was appointed inspector of the pharmacy at the Hôtel-Dieu (the Paris hospital) and in 1731 he served as a Paris alderman (échevin).

In 1707 Geoffroy, who had studied botany under J. P. de Tournefort and made a long field excursion in the south of France in 1704-1705, was elected to the Académie des Sciences as a botanist. He was already interested in chemistry and in his first research tried to find a chemical explanation of the colors of plants (1707). He discovered that the oil obtained by macerating and distilling thyme reacted with vinegar, potash, and other substances of vegetable origin to form colors similar to those in flowers and leaves and this supported the belief that plants consisted of a limited number of principles combined in different ways and obtainable by simple processes such as distillation and fermentation.

After publishing a few botanical papers, Geoffroy transferred to the chemical section of the Academy in 1715. Much of his subsequent research arose from his pharmaceutical work, a good example being his discovery that sedative salt (boric acid), a medicament normally prepared in small quantities by subliming a mixture of borax and iron vitriol (ferrous sulfate), could be made on a larger scale by treating borax with diluted oil of vitriol (sulfuric acid) and crystallizing it (1732). This research was important in the development of theoretical as well as practical chemistry for Geoffroy demonstrated the presence of a common constituent in borax, soda, and common salt, all of which yielded Glauber’s salt (sodium sulfate) on treatment with sulfuric acid.

Geoffroy’s son, Claude François Geoffroy (ca 1728-1753; incorrectly called N. Geoffroy in Nouvelle biographie générale) succeeded him in his profession and was elected to the chemical section of the Academy in 1752.

BIBLIOGRAPHY

I. Original Works. About sixty papers by Geoffroy were published in Historie et mémories de l’Académie royale des sciences. A complete list is given by P. Dorveaux (see below).

II. Secondary Literature. A general account of Geoffroy’s life and work is J. P. Grandjean de Fouchy, “Éloge de M. Geoffroy,” in Histoire de l’Academie royale des sciences (1752, pub. 1756), 153-164. Further information is given by P. Dorveaux, “Claude-Joseph Geoffroy,” in Revue d’histoire de la pharmacie, 3 (1932), 113-122, pib. on pp. 119-122. Dorveaux also gives an account of his son, “Claude François Geoffroy,” ibid., 122-126. There seems to be no connection between the Geoffroy family and that of Étienne and Isidore Geoffroy Saint-Hilaire the naturalists, according to G. Plancnon, ’’La dynastie des Geoffroy, apothicaires à Paris,” in Journal de pharmacie et de chimie, 6th ser., 8 (1898), 289-293, 337-345 (esp.344-345).

W. A. Smeaton