IN THE ANIMAL ORGANISM. 207 



If we check the propagation of the current of force, 

 the acid retains its chemical character. If 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 par- 

 ticle of acid after another changes its properties. 



In the preceding paragraphs we have considered 

 these remarkable phenomena in a form which is inde- 

 pendent 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 conduc- 

 tor 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 supposi- 

 tions 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 ma ilfested. 



On some points, however, there is no doubt ; name- 

 ly, that all the effects which may be produced by the 

 wire are determined by the change of properties 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 substance which propagates in all direc- 

 tions, where it is not neutralized by resistance, the 

 force or momentum produced ; that this force becomes 

 a momentum of motion, by means of which we can 



