CHEMISTRY SINCE TIME OF DALTON 



in definite proportions. Berthollet, the great co-worker 

 with Lavoisier, and now the most authoritative of living 

 chemists, contended that substances combine in almost 

 indefinitely graded proportions between fixed extremes. 

 He held that solution is really a form of chemical com- 

 bination a position which, if accepted, left no room for 

 argument. 



But this contention of the master was most actively 

 disputed, in particular by Louis Joseph Proust, and all 

 chemists of repute were obliged to take sides with one 

 or the other. For a time the authority of Berthollet 

 held out against the facts, but at last accumulated evi- 

 dence told for Proust and his followers, and towards 

 the close of the first decade of our century it came to 

 be generally conceded that chemical elements combine 

 with one another in fixed and definite proportions. 



More than that. As the analysts were led to weigh 

 carefully the quantities of combining elements, it was 

 observed that the proportions are not only definite, but 

 that they bear a very curious relation to one another. 

 If element A combines with two different proportions of 

 element B to form two compounds, it appears that the 

 weight of the larger quantity of B is an exact multiple 

 of that of the smaller quantity. This curious relation 

 was noticed by Dr. Wollaston, one of the most accurate 

 of observers, and a little later it was confirmed by 

 Johan Jakob Berzelius, the great Swedish chemist, who 

 was to be a dominating influence in the chemical world 

 for a generation to come. But this combination of ele- 

 ments in numerical proportions was exactly what Dal- 

 ton had noticed as early as 1802, and what had led him 

 directly to the atomic weights. So the confirmation of 



