French chemist and physicist, born at St. Leonard, Haute-Vienne; at the Polytechnic School, Paris, his abilities attracted the attention of Berthollet (q. v .), who appointed him his assistant in the government chemical works at Arcueil; here he assiduously employed himself in chemical and physical research, in connection with which he made two balloon ascents; in 1809 he became professor of Chemistry at the Paris Polytechnic School; in 1832 was elected to a similar chair at the Jardin des Plantes; seven years later was created a peer of France, while in 1829 he became chief assayer to the Mint; his name is associated with many notable discoveries in chemistry and physics, e. g . the law of volumes, isolation of cyanogen, &c. (1778-1850).