MancJiester Memoirs, Vol. liv. (19 lo), No. 7. 9 



E. von Meyer says that " none of the other leading 

 chemists of the day raised any objections." '* This puts 

 the matter too strongly, for Thenard, who had previously 

 been on Berthollet's side, showed signs of veering round 

 in 1805. " I ^'^ quite persuaded that the number of 

 oxides of the metals is much greater than the majority of 

 chemists allow, . . . but I declare that I am not yet con- 

 vinced that there are as many oxides as there are possible 

 degrees of oxidation ; and if theory allows of them, 

 experience seems to reject them."'" In this paper he 

 maintains that there are not two oxides of iron (as Proust 

 said) but three."'' Proust must have had some adherents, 

 but I do not know of any, unless Thomas Thomson be 

 one,'^ who gave him open support. Thenard does not 

 mention him. There is extremely little sign that he 

 was considered to have made out his case. Further, there 

 is every reason to think that the change of opinion, when 

 it came, was due to quite another influence than Proust. 

 What was effective was the working hypothesis which the 

 atomic theory supplied. 



The influence of Dalton began to permeate chemistry 

 about the year 1808. For some years he had been 

 making endeavours, not very successful ones, to arouse 

 interest in his theory of chemical combination. In parti- 

 cular, Humphrey Davy,^* with all his powers of imagina- 

 tion, had failed to see anything in it. A much less 



^* "Hist, of Chem.," Eng. trans., p. 194, 1906. 



^^ Anil, de Chiiii., vol. 56, p. 62, 1S05. 



^^ Op. lit., pp. 66, 77. 



=2^ See Nicholson's Joiirn., vol. 8, pp. 280—281, 1804. 



2 8 Davy must surely have heard of the atomic theory when Dalton was 

 lecturing at the Royal Institution of* London in 1803— 1804 (see Henry's 

 "Life of Dalton," pp. 47 — 50, and Dalton's " New System of Chemical 

 Philosophy," p. v., 1808). He certainly discussed it with Thomas Thomson 

 in 1807 and poured ridicule on it then. (See Thomson's " History of 

 Chemistry," vol. 2, p. 293.) 



