The work of the great Swedish chemist is characterized by thoroughness in all its parts: to him every fact appeared to be of importance; although now perhaps only an isolated fact, he saw that some day it would find a place in a general scheme of classification. He worked in great measure on the lines laid down by Dalton and Davy; the enormous number and accuracy of his analyses established the law of multiple proportions on a sure basis, and his attempts to determine the constitution of compound atoms, while advancing the atomic theory of Dalton, drew attention to the all-important distinction between atom and molecule, and so prepared chemists for the acceptance of the generalization of Avogadro. The electro-chemical conceptions of Davy were modified by Berzelius; they were shorn of something of their elasticity, but were rendered more suited to be the basis of a rigid theory.
At the close of this transition period from the Lavoisierian to the modern chemistry, we find analytical chemistry established as an art; we find the atomic theory generally accepted, but we notice the existence of much confusion which has arisen from the non-acceptance of the distinction made by Avogadro between atom and molecule; we find the analogies between chemical affinity and electrical energy made the basis of a system of classification which regards every compound atom (or molecule) as built up of two parts, in one of which positive, and in the other negative electricity predominates; and accompanying this system of classification we find that an acid is no longer regarded as necessarily an oxygen compound, but rather as a compound possessed of certain properties which are probably due to the arrangement of the elementary atoms, among which hydrogen appears generally to find a place; we find that salts are for the most part regarded as metallic derivatives of acids; and we find that by the decomposition of the supposed elementary substances, potash, soda, lime, etc., the number of the elements has been extended, the application of a new instrument of research has been brilliantly rewarded, and the Lavoisierian description of "element" as the "attained, not the attainable, limit of research" has been emphasized.
FOOTNOTES:
[9] The history and meaning of these terms is considered on p. 171, et seq.
[10] For an explanation of this expression, "chemical affinity," see p. 206, et seq.
[11] These views have been already explained on pp. 182, 183.
