The Berthollet-Proust controversy and Dalton's atomic theory are two important historical landmarks which appeared almost simultaneously at the very beginning of the nineteenth century. Therefore it is likely that between the theory of definite proportions—one of the main subjects of the controversy–and Dalton's atomic theory there was an important interrelation, and that they reinforced each other. Kapoor has suggested that Proust could not have been the forerunner of Dalton's law of constant and multiple proportions, because Dalton discovered his law from (...) completely different premises, and does not seem to have got his ideas from Proust. In my opinion, however, his conclusion does not seem to be decisive. (shrink)