A HISTORY OF SCIENCE 



ing lights of chemistry still looked askance at Dalton's 

 explanation of this law. Thus Wollaston, though from 

 the first he inclined to acceptance of the Daltonian view, 

 cautiously suggested that it would be well to use the 

 non-committal word "equivalent" instead of "atom"; 

 and Davy, for a similar reason, in his book of 1812, 

 speaks only of " proportions," binding himself to no the- 

 ory as to what might be the nature of these proportions. 

 At least two great chemists of the time, however, 

 adopted the atomic view with less reservation. One 

 of these was Thomas Thomson, professor at Edin- 

 burgh, who, in 1807, had given an outline of Dalton's 

 theory in a widely circulated book, which first brought 

 the theory to the general attention of the chemical 

 world. The other and even more noted advocate of the 

 atomic theory was Johan Jakob Berzelius. This great 

 Swedish chemist at once set to work to put the atomic 

 theory to such tests as might be applied in the labora- 

 tory. He was an analyst of the utmost skill, and for 

 years he devoted himself to the determination of the 

 combining weights, "equivalents" or "proportions," 

 of the different elements. These determinations, in 

 so far as they were accurately made, were simple ex- 

 pressions of empirical facts, independent of any theory ; 

 but gradually it became more and more plain that 

 these facts all harmonize with the atomic theory of 

 Dalton. So by common consent the proportionate 

 combining weights of the elements came to be known 

 as atomic weights the name Dalton had given them 

 from the first and the tangible conception of the 

 chemical atom as a body of definite constitution and 

 weight gained steadily in favor. 



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