OHM ON THE GALVANIC CIRCUIT. 495 



when z = 0, or z = I, i. e. when the body to be decomposed is 

 not compound ; thirdly, when m ^ — n z = 0, i. e. when the den- 

 sities of the constituents are proportional to the latent electro- 

 scopic forces which they possess, which circumstance can never 

 occur with constituents of opposite electric nature. 



All the expressions here given for the decomposing force of 

 the circuit refer to the entire section belonging to the respective 

 place ; if we wish to reduce the value of the decomposing force 

 to the unity of surface, the expression must be divided by the 

 magnitude of the section, to which attention has been already 

 called in § 30, in a similar example. 



33. If this decomposing force of the circuit is able to over- 

 come the coherence of the particles in the disc, a coherence pro- 

 duced by their electric opposition, this necessarily occasions 

 a change in the chemical equivalent of the particles. But such 

 a change in the physical constitution of the circuit must, 

 at the same time, react on the electric current itself, and give 

 rise to alterations in it, with which a more accurate acquaintance 

 is desirable, and which we will therefore spare no trouble to 

 acquire. 



For this purpose we will imagine a portion of the galvanic 

 circuit to be a homogeneous fluid body, in which such a decom- 

 position actually takes place ; then, at all points of this portion, 

 the elements of one kind will tend to move with greater force 

 towards one side of the circuit than those of the other kind ; 

 and since we suppose that, by the active forces, the coherence 

 is overcome, it follows, if we pay due attention to the nature 

 of fluid bodies, that the one constituent must pass to one side, 

 those of the other constituent, on the contrary, towards the 

 other side of the portion, which necessarily produces on one 

 side a preponderance of the constituent of one kind, and on 

 the other side a preponderance of the other kind of constitu- 

 ent. But as soon as a constituent is predominant on one side 

 of any disc, it will oppose by its preponderance the movement 

 of the like constituent in the disc towards the same side, in con- 

 sequence of the repulsive force existing between both ; the de- 

 composing force, therefore, has now not merely to overcome 

 the coherence between the two constituents in the disc, but 

 also the reacting force in the neighbouring discs. Two cases 

 may now occur; the decomposing force of the electric cur- 

 rent either constantly overcomes all the forces opposed to it. 



