Bioqraphy of Berzelius. 209 



most important experiments, by which the theory of Dalton 

 was proved, were instituted by Wollaston, who published in 

 the year 1814 his ingenious scale of chemical equivalents. 



When the numbers made use of by Dalton are compared 

 with those which Berzelius deduced from his own accurate 

 experiments, differences are found similar to those existing 

 between these latter and those given by Richter. The num- 

 ber of analyses upon which Dalton had founded his arguments 

 was too small, and moreover they had not been executed with 

 very great accuracy. 



In the selection of a substance which should be taken as 

 unity, so as to make the atomic weights found, comparable 

 with each other, chemists hesitated between hydrogen and 

 oxygen. Dalton chose hydrogen, and took it as =1 since its 

 atom is the lightest of all the elements. Many chemists fol- 

 lowed his example on this account, especially after Prout had 

 subsequently attempted to shew that the atomic weights of 

 all simple bodies were multiples of that of hydrogen. Richter 

 had long before entertained a similar view, inasmuch as he as- 

 sumed that the equivalents of all bases form an arithmetical, 

 those of acids a geometrical progression. Nevertheless, Ber- 

 zelius and Wollaston took oxygen as unity, because it was the 

 most widely-distributed of all the elements, and existed in most 

 compound substances. By adopting oxygen as unity, all cal- 

 culations were greatly simplified. Berzelius took it as = 100, 

 Wollaston = 10. Berzelius remained true to his opinion 

 to the last, and always declared himself against that of Prout, 

 even when in, 1840, it was again adopted by Dumas, who at- 

 tempted to prove its truth for at least a few elements by 

 actual experiment. It is true that the atomic weights of 

 several of the non-metallic elements appear to be multiples of 

 that of hydrogen, but it has not been possible to maintain 

 Prout' s views as regards others. So long as we are ignorant 

 whether this correspondence is merely accidental, or actually 

 a law of nature we must suspend a decision. 



In the determination of the number of atoms in compound 

 bodies, Berzelius proceeded with great caution. Dalton and 

 others, who had put forward the view that substances com- 

 bine, especially in such proportions that one atom of the one 



