Gay-Lussac, Joseph Louis 1778-1850
French chemist and physicist

Born in Saint-L�onard, Haute Vienne, he was educated at the �cole Polytechnique and the �cole des Ponts et Chauss�es. He became assistant to Claude Louis Berthollet in 1800 and subsequently held various posts, including Professor of Chemistry at the �cole Polytechnique (from 1810), Professor of Physics at the Sorbonne (1808-32), Professor of Chemistry at the National Museum of Natural History (from 1832), superintendent of the government gunpowder factory (from 1818) and chief assayer to the Mint (from 1829). He became an Academician (1806), member of the Chamber of Deputies (1831) and member of the Upper House (1839). He was elected an honorary Fellow of the Chemical Society in 1849. His earliest research work was on the expansion of gases with temperature increases, and he discovered independently the law which in Great Britain is commonly known as Charles's law. In 1804 he made balloon ascents in association with Jean Baptiste Biot to make magnetic and atmospheric observations, and he travelled with Baron Alexander von Humboldt (1805-06), making measurements of terrestrial magnetism. In 1808 he published his important law of gas volumes. This was based on work which he had begun with Humboldt in 1805. From around 1808 Gay-Lussac's work became more purely chemical, and much of it was done in collaboration with Louis Jacques Th�nard. Their work included the isolation and investigation of sodium, potassium, boron and silicon, extensive studies of the halogens (involving controversy with Sir Humphry Davy), and the improvement of methods of organic analysis. His last great pure research was on prussic acid and cyanogen and their derivatives. During the later part of his career, he did much work as a technical adviser to industry.

Bibliography: Maurice Crosland, Gay-Lussac, Scientist and Bourgeois (1978)