218 THE PHENOMENA OF MOTION 



we employ it to overcome chemical or mechanical 

 resistance, to decompose chemical compounds, or 

 to produce motion, the chemical action continues ; 

 that is to say, one particle of acid after another 

 changes its properties. 



In the preceding paragraphs we have considered 

 these remarkable phenomena in a form which is 

 independent of the explanations of the schools. Is 

 the force which circulates in the wire the electrical 

 force? Is it chemical affinity? Is it propagated 

 in the conductor like a fluid set in motion, or in 

 the form of a series of momenta of motion, like 

 light and sound, from one particle of the conductor 

 to another? All this we know not, and we shall 

 never know. All the suppositions which may be 

 employed as explanations of the phenomena have 

 not the slightest influence on the truth of these 

 phenomena ; for they refer merely to the form in 

 which they are manifested. 



On some points, however, there is no doubt ; 

 namely, that all the effects which may be produced 

 by the wire are determined by the change of pro- 

 perties in the zinc and in the acid ; for the term 

 " chemical action " signifies neither more nor less 

 than the act of change in them ; that these effects 

 depend on the presence of a conductor, of a sub- 

 stance which propagates in all directions, where it 

 is not neutralized by resistance, the force or mo- 

 mentum produced ; that this force becomes a mo- 

 mentum of motion, by means of which we can pro- 



