162 



SCIENTIFIC THOUGHT. 



generally attributed to gases. Andrews l in the 'sixties 

 carried on his important experiments on the transition of 

 bodies from the liquid to the gaseous state, and came to 

 the conclusion " that the gaseous and liquid states are 

 only remote stages of the same condition of matter, and 

 are capable of passing into one another by a process 

 of continuous change." 2 He also referred to the " pos- 

 sible continuity of the liquid and solid states of matter." 

 Another important step by which our conceptions of 

 the nature of the liquid condition of matter were con- 

 siderably enlarged and altered motion being introduced 

 where a former view had seen only rest was taken by 

 Clausius, who, following Joule and Kronig, had about the 

 same time given its modern form to the kinetic theory 

 of gases. What suggested this step was the pheno- 

 menon of electrolysis. The older view looked upon the 

 action of the electric current, which, passing through 

 substances in a state of fusion or solution, liberated the 

 constituents out of which they were composed, as an 

 exertion of a force contrary to the forces of chemical 

 affinity, by which the chemical constituents were sup- 

 posed to be held together. In this case energy would 

 have to be spent in doing work against chemical forces. 

 It was, however, very soon found that the decomposi- 

 tion, or as Sainte Claire Deville first called it 3 the 



1 See vol. i. p. 316, note, of this 

 History. 



2 See 'The Scientific Papers of 

 'Thomas Andrews,' with a Memoir 

 by Tait and Crum Brown, London, 

 1889, p. 316. 



3 Sainte Claire Deville (1818-81) 

 approached chemical research from 

 the side of medicine, and after a 



series of original investigations, first 

 in organic then in metallurgical 

 chemistry, entered upon his re- 

 markable work in thermal chem- 

 istry at the time when Clausius in 

 Germany was being led from an 

 entirely different point of view to 

 the same subject. He introduced 

 the term dissociation to denote the 



