The slow emergence of Dalton's chemical atomic theory has long been a considerable puzzle to historians of science The lengthy delay between Dalton's early work on mixed gases and particle weights and the eventual publication of the first part of his New System of Chemical Philosophy has called forth a variety of explanations. It is now more than half a century since A. N. Meldrum stressed“…the efforts Dalton had to make, in order to arouse attention to the importance of his (...) ideas regarding atoms. For some nine years , if not longer, he endeavoured to spread abroad his ideas, both by private communications and publicly, by his writings and by lectures in various parts of the country…“Dalton's chemical theory was formed by the 6th September 1803, and he proceeded forthwith to extend and apply it, and make it known in every direction…”And though Meldrum's view is now no longer accepted, no systematic and detailed account of Dalton's activities over these years is available to replace Meldrum's assertions. (shrink)

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)