THE ATOMIC VIEW OF NATURE. 



401 



the chemist was enormous, offering a large, ahnost limit- 

 less, field of research and speculation. Let us see under 

 what leading ideas this knowledge has been arranged. 



In the gradual development and clearer definition of 

 these conceptions a general rule of thought seems to 

 have unconsciously guided philosophers probably more 

 than in any other department of knowledge. It is the 

 rule of simplicity.-^ How the human mind should have 

 arrived at the old formula of " simplex sigillum veri " is 

 difficult to understand on any other ground than that of 

 convenience and expediency. The prevailing impression, 

 indeed, which the world of phenomena makes on the mind 

 of an unbiassed observer must be the very reverse of sim- 

 plicity or unity of law and purpose. That, nevertheless, 

 the knowledge of some simple relations in time, number, 

 and space would enable the human intellect to acquire a 

 considerable insight into the course of events and the 

 order of Nature's processes must have come to philosophers 



14. 



" Simplex 



sigillum 



veri." 



1 The progress of chemical theory 

 is the history of the attempt to 

 find simple relations of number and 

 form, representing the countless 

 combinations of elementary sub- 

 stances ; and of the growing con- 

 viction that nearly every simpli- 

 fication must, in course of time, 

 be abandoned. No formula remains 

 unchallenged except the doctrine of 

 fixed and fixed multiple proportions, 

 and that only if we confine our- 

 selves to solid compounds ; but the 

 proportions themselves are not ac- 

 curately known, though no pheno- 

 menon exists which disproves the 

 assumption that thej' are invariable. 

 The original conception of the atom 

 as a round hard Vjody had to be 

 abandoned for the more complicated 



VOL. I. 



notion of a molecule, an assemblage 

 of atoms ; the conception of elemen- 

 tary bodies had to be amplified by 

 that of compound elements or 

 radicles ; the idea that the atomic 

 weights were multiples of a lowest 

 number had to be abandoned ; the 

 binary theory of the combination 

 of bodies was replaced by the theory 

 of radicles, of nuclei, of types ; the 

 simple nature of the elementary 

 particles had to give way to a 

 complicated atomicity, from which 

 there had to be again distinguished 

 the valency or capacity of satura- 

 tion of the elementary constitu- 

 ents. It is a progress from simpler 

 to more and more complex methods 

 of representation. 



2 c 



