THE CENTURY'S PROGRESS IN CHEMISTRY 



The atomic weight of oxygen then becomes (as given in 

 Dalton's first table of 1803) 5.5 ; that of water (hydrogen 

 plus oxygen) being of course 6.5. The atomic .weights 

 of about a score of substances are given in Dalton's first 

 paper, which was read before the Literary and Philo- 

 sophical Society of Manchester, October 21, 1803. 1 

 wonder if Dalton himself, great and acute intellect 

 though he had, suspected, when he read that paper, that 

 he was inaugurating one of the most fertile movements 

 ever entered on in the whole history of science \ 



IT 



Be that as it may, it is certain enough that Dalton's 

 contemporaries were at first little impressed with the 

 novel atomic theory. Just at this time, as it chanced, a 

 dispute was waging in the field of chemistry regarding 

 a matter of empirical fact which must necessarily be 

 settled before such a theory as that of Dalton could 

 even hope for a hearing. This was the question whether 

 or not chemical elements unite with one another always 

 in definite proportions. Berthollet, the great co-worker 

 with La\ T oisier, 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 al) 

 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- 



255 



