Manchester Memoirs, Vol. Iv. (191 1), No. 5. 7 



before this Society and then published, expressing his 

 entire satisfaction with it. "In the discussions... which 

 took place in the Society on your several papers, the 

 doctrine of mixed gases was opposed by almost every 

 member interested in such subjects, and by no one more 

 strenuously than myself I am now satisfied that... 

 your theory is better adapted than any former one, for 

 explaining the relation of mixed gases to each other, and 

 especially the connection between gases and water." '■ 



This support must have been specially gratifying to 

 Dalton, in view of the keen opposition and criticism 

 which the theory was receiving in other quarters. It 

 probably confirmed and enhanced the "almost life-long 

 friendship " between the two men, which is referred to 

 repeatedly in this series of papers. 



The ''' mixed gases'' controversy. 



The controversy which was aroused by Dalton's 

 theory of mixed gases affords proof at once of the interest 

 taken in his mechanical explanation of the phenomenon, 

 and of the tenacity with which the chemical explanation 

 was adhered to. The view that air is a chemical compound 

 was maintained with a persistency which is hardly credible 

 now, and which throws into relief the originality and 

 vigour of mind which Dalton showed in forming and 

 urging a wiser view. The balance of opinion was against 

 him, for his opponents included Claude Louis Berthollet, 

 Thomas Thomson, John Gough, John Murray, and 

 Humphry Davy. 



Dalton's contention, that the diffusion of gases is a 

 physical phenomenon, was at length fully and finally 

 recognised in the Kinetic Theory of Gases. Meantime 

 Dalton had to do his best in the circumstances, and the 



^- NicholsoiC s Journ., [2], vol. 8, p. 297, 1S04. 



