The development of the atomic theory.

Andrew Norman Meldrum

Date:: [1910-1911]

Catalogue details

Licence: In copyright

Credit: The development of the atomic theory. Source: Wellcome Collection.

90/114 page 2

to theory may exert a harmful effect on science, by despising and rejecting a theory of the utmost importance. The usefulness to science of the atomic theory is so completely established now, that it must seem strange to us to observe 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. As will be seen, Dalton’s speculations had to encounter dangers of two kinds. In the first place, not many people gave themselves much concern about the question of the continuity or discontinuity of matter. They were quite content to go on speaking of *‘ atoms ” and “molecules” in a vague, colloquial sense, and Dalton had to induce them, if possible, to use the words as terms of precision. This done, there was always the possibility that the}’ would reject Dalton’s idea of an atom as too hypothetical. His physical atomic theory (described in the fourth paper of this series) was devised in the year 1801, from which time onwards he made many attempts to recommend it to the scientific world. But for years the only avowed adherent which it obtained was William Henry. The question at issue was a fundamental one, and Dalton’s finding on it was ultimately triumphant. The theory ex- pressed his conviction that the diffusion of gases is due to physical forces and not to chemical. But the prevailing tendency of the time was to regard diffusion as due to chemical affinity between the gases concerned, and the strength of that tendency was exhibited by the amount of opposition to Dalton’s theory. Its opponents included

digitised image 1

digitised image 2

digitised image 3