1754-1826

French chemist famous for discovering the law of constant proportions, or Proust's law, according to which pure samples of a compound always contain the same elements in definite proportions. His views contradicted Claude-Louis Berthollet's widely accepted claim that compound composition varies depending on how the compounds are prepared. Proust prevailed, but it was later shown that some compound compositions vary slightly—sometimes referred to as berthollides. Proust was the first to identify and study glucose.