420 Prof. A. de la Rive's Memoir of 



rent. We may add, so as not to return to the subject, that 

 Faraday sometimes had doubts upon this point, and that he even 

 thought that water could conduct electricity without being de- 

 coniposed. Now experiment shows that in all cases, even those 

 which appear most favourable to this opinion, electricity cannot 

 be transmitted under any form through a compound liquid body 

 without this body undergoing electrochemical decomposition. 



As to the causes of conductibility, they are still far from being 

 known ; when we see bodies, such as the gases, becoming conduc- 

 tors when greatly rarefied, whilst under the ordinary pressurethey 

 are perfect insulators, we are compelled to come to the conclu- 

 sion that the impossibility that we find of explaining this differ- 

 ence, as well as so many others presented in this respect by solid 

 and liquid bodies, is due to the fact that we have not yet a cor- 

 rect notion of the molecular constitution of bodies. Perhaps 

 the recent theories of several physicists, particularly that of 

 Clausius, who regards the particles of bodies as being in a con- 

 stant state of movement, may succeed in elucidating this subject, 

 w r hich is still so mysterious. Faraday himself had fully foreseen 

 this relation between electrical conductibility and the ideas which 

 we may form as to the nature of matter. In a remarkable 

 article published in 1844 he showed, upon an experimental 

 basis, that, in the theory according to which a body is regarded 

 as consisting of atoms possessing weight separated from each 

 other by larger or smaller intermolecular intervals, there are a 

 multitude of facts, some of which can only be explained by assu- 

 ming that the atoms are the conductors and the molecular space 

 an insulator, and the others by supposing that the intermole- 

 cular space is the conductor and the atoms insulators — a contra- 

 diction which is inadmissible. He concluded from this that 

 we must imagine matter to be continuous, or rather imagine the 

 atoms to be simply centres of force, and consequently replace 

 the atomistic by the dynamical theory. We shall often find 

 traces of these ideas in the subsequent works of Faraday ; for 

 ourselves we cannot take this view. We are convinced that it is 

 not by denying the existence of matter, properly so called, and 

 admitting only that of forces, that we shall succeed in solving 

 the difficulties under consideration and many others, but rather, 

 following the example of Clausius and others, by modifying the 

 ideas hitherto accepted as to the mode of constitution of bodies, 

 and replacing them by others more in accordance with recent 

 discoveries. 



But we must return to electrochemistry. I have already said 

 that Faraday first occupied himself with chemical decompositions 

 effected by the electrical current. He commences by effecting 

 the decomposition of water and of solutions by means of a jet of 



