2 26 Literary and Philosophical Society, 



if it be anything but cohesion. Still the two must meet 

 somewhere.^ 



The following still holds good. ' It really is a melan- 

 choly thing to read these papers of Proust. . . . He saw ^ 

 with great clearness that without such constant proportion 

 the products of nature would lose their stability, and the 

 characters of bodies could not be depended on for perma- 

 nence. We have here no difficulty in judging how much 

 he did, and how much he left undone, how far his mind 

 was advanced, and how it had merely speculated. When 

 he uses 4-i, + 2, + 3 of proportions, he tells us that it is 

 merely for illustration, he did not mean it to indicate the 

 order of combination ; he had, in fact, made no theory, at 

 least found no law on the subject, although he clearly saw 

 that it must be owing to some law of nature. He sought 

 for constant proportions in combination, and sought well, 

 but he had no idea of a constant quantity of oxygen found 

 uniting with a constant quantity of every metal and 

 making higher oxides by steps always of an equal altitude, 

 although he proved that the rise may not be that of an 

 inclined plane, but by " fixed terms." And yet it follows as 

 a consequence, so closely in fact does it follow that we 

 must put ourselves in the position of the early chemists of 

 the century well to understand the difference. When we 

 have taken that position, we then see how thin was the 

 veil, although utterly impenetrable, that divided his opinion 

 from the present, and prevented the acute, accurate, and 

 logical mind of Proust from attaining to the great dis- 

 covery. His determinate proportions are given as remark- 



• The writer has shown that in the case of absorption of gases by charcoal 

 definite laws are followed by cohesion, but proportions different from chemical 

 equivalents are observed. 



' History of the Atomic Theory up to the time of Dalton, p. 226. 



