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.

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    sider, perhaps to realise for the first time, precisely what their position is. Such was the case of the doctrine of constant proportion. It seems to have arisen naturally and been taken for granted, assumed as a matter of course, rather than considered and carefully defined. Suddenly, about the beginning of the XIXth century, it was called in question by Berthollet. Primarily his teaching was concerned with the pro- blems of chemical affinity. lie had ample leisure to meditate on the subject during his stay in Egypt, where he had gone as an honoured member of the famous Napoleonic expedition. The first fruits of that leisure appeared in papers, read in Cairo before the shortlived Institute of Egypt in June of the year 1799, in which he propounded the valuable and original ideas of “mass- action ” and chemical equilibrium. Berthollet was thus the founder of chemical statics. Resuming the subject on his return to France, he developed his ideas into a system of chemistry, which is explained in various Memoirs1 and above all in his “ Essai de Statique Chimique,” (2 vols., 1803). His teaching aroused interest everywhere, witness the appearance of English and German translations of his works, and the extent to which his ideas permeated the scientific dissertations2 and books of the period. His main contention that chemical change was very largely a matter of two factors, affinity and mass-action, could hardly be denied. The tables of affinity which in the course of the XVIIIth century had become more and 1 “ Recherches sur les lois de l’Affinite,” MCm. de tInstitute vol. 3, pp. 1, 207, 228, j8oi ; vol. 7, 229, 1806. 2 Memoirs, in which Proust, Thenard, Gay-Lussac, Avogadro, Berzelius, and Dalton take Berthollet’s ideas into consideration will be cited as occasion requires. A supplementary list of memoirs not specially referred to in this paper, will he found in an appendix.
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