THE CENTURY'S PROGRESS IN CHEMISTRY 



This, however, was not strange, for of course the law 

 of Avogadro is based on the atomic theory, and in 1811 

 the atomic theory was itself still being weighed in the 

 balance. The law of multiple proportions found general 

 acceptance as an empirical fact ; but many of the leading 

 lights of chemistry still looked askance at D.alton's ex- 

 planation 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 

 theory as to what might be the nature of these propor- 

 tions. 



At least two great chemists of the time, however, adopt- 

 ed the atomic view with less reservation. One of these 

 was Thomas Thomson, professor at Edinburgh, 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 chem- 

 ist at once set to work to put the atomic theory to such 

 tests as might be applied in the laboratory. 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 ele- 

 ments. These determinations, in so far as they were 

 accurately made, were simple expressions of empirical 

 facts, independent of any theory ; but gradually it be- 

 came more and more plain that these facts all har- 

 monize with the atomic theory of Dalton. So by com- 

 mon consent the proportionate combining weights of 



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