TRANSITION TO CHEMICAL SCIENCE. 2.57 



have ascertained, we will suppose, the laws of Electric Polarity ; but 

 we have then to ask, What is the relation of this Polarity to Chemical 

 Composition ? This was the great problem which, constantly present 

 to the minds of electro-chemical inquirers, drew them on, with the 

 promise of some deep and comprehensive insight into the mechanism 

 of nature. Long tasks of research, though only subsidiary to this, 

 were cheerfully undertaken. Thus Faraday 1 describes himself as 

 compelled to set about satisfying himself of the identity of common, 

 animal, and voltaic electricity, as " the decision of a doubtful point 

 which interfered with the extension of his views, and destroyed the 

 strictness of reasoning." Having established this identity, he pro- 

 ceeded with his grand undertaking of electro-chemical research. 



The connexion of electrical currents with chemical action, though 

 kept out of sight in the account we have hitherto given, was never 

 forgotten by the experimenters ; for, in fact, the modes in which elec- 

 trical currents were excited, were chemical actions; the action of 

 acids and metals on each other in the voltaic trough, or in some other 

 form. The dependence of the electrical effect on these chemical 

 actions, and still more, the chemical actions produced by the agency 

 of the poles of the circuit, had been carefully studied ; and we must 

 now relate with what success. 



But in what terms shall we present this narration ? We have 

 spoken of chemical actions, but what kind of actions are these .' 

 Decomposition ; the resolution of compounds into their ingredients ; 

 the separation of acids from bases ; the reduction of bodies to si>j>/i 

 elements. These names open to us a new drama ; they are words 

 which belong to a different set of relations of things, a different train 

 of scientific inductions, a different system of generalizations, from any 

 with which we have hitherto been concerned. ' We must learn to 

 understand these phrases, before we can advance in our history of 

 human knowledge. 



And how are we to learn the meaning of this collection of words : 

 In what other language shall it be explained ? In what terms shall 

 we define these new expressions ? To this we are compelled to reply, 

 that we cannot translate these terms into any ordinary language ; 

 that we cannot define them in any terms already familiar to us. Here, 

 as in all other branches of knowledge, the meaning of words is to be 

 sought in the progress of thought ; the history of science is our clic- 



1 Dec. 1832. Researches, 266. 

 VOL. II. 17 



