Joseph Louis Proust, b. Sept. 26, 1754, d. July 5, 1826, was a French chemist whose careful research on many chemical substances demonstrated convincingly that each pure compound has a characteristic elemental composition. In a famous controversy (1801-07) with his compatriot Claude Berthollet concerning the constancy of chemical composition, Proust's position prevailed and was subsequently established as the law of constant proportions.
Ralph Gable
Last modified on: Saturday, October 18, 1997.