418 LIFE OF D ALTON: 



his sliding-scale of chemical equivalents offered a very in- 

 genious instrument for its application to practical chemistry. 

 In determining by beautiful experiments the law of combina- 

 tion of volumes in equal or multiple proportions, Gray-Lussac 

 added fresh evidence, better appreciated by others than by 

 Dalton himself. Meanwhile Berzelius, in his Northern labora- 

 tory, executed those numerous and admirable analyses, which, 

 fulfilling in their results every condition of the atomic theory, 

 obtained for it the general acquiescence of the scientific 

 world. The tables he constructed of atomic weights have re- 

 quired little change but that of enlargement. The ingenious 

 system of chemical formulae which he devised, denoting these 

 atomic relations, was speedily accepted by chemists and has 

 since been very generally employed. 



The remaining history of the progress of this discovery as 

 it comes down to our own time, and of its influence in every 

 branch of physical research, cannot so easily be made clear to 

 our general readers. The chemists of the present day more 

 especially, deriving impulse -from the atomic doctrines, have 

 carried these as instruments into parts of science hitherto 

 inaccessible to research ; fully attesting by their success the 

 validity of the means so employed. The whole domain of 

 Organic Chemistry may be said to be a recent conquest thus 

 obtained. The laws of isomorphism, of isomerism, of atomic 

 substitution, of compound radicals, have all been determined 

 during the same period by the genius and labours of Mitscher- 

 lich, Liebig, Hofmann, Dumas, and other foreign and British 

 chemists. It would be beside our present object, and indeed 

 impossible here, to give any adequate idea of these abstruse 

 and difficult researches. We allude to them only to mention 

 how completely they are interwoven with the atomic prin- 

 ciple, and how thoroughly they illustrate its various workings 

 in the natural world. 



There are one or two points, however, of which we may 



