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 (September 1801) and particle weights (September 1803) and the eventual publication of the first part of his New System of Chemical Philosophy (June 1808) 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 (1801-1810), 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.