80 Relation between Chemic at Change, [January, 



2(nRb + rw) 

 Or the circulating quantity of electricity is half what it was, 

 and consequently only half the metal is consumed, but as 

 H = I*R, this equation will now become — 



H={_-^ \ 2 X2(nRb + rw) 



{2{nRb~\-rw) 



n 2 E 2 



2{nRb + rw) 



That is, the quantity of heat is now half what it was, and 

 only half the metal is consumed. 



In this case the theory is consistent with itself. ' 

 6. Let us take one more case in which it is so. Double 

 the number of cells and double the resistance in the con- 

 ducting wire; then — 



t 2nE nE 



2{nRb + rw) nRb-\-rw 

 but now H becomes — 



RI Y — nEV X2 ( wR fi +yT fe) = g " aE * 



ynRb + rwJ nRb-\-rw 



or double what it was before ; that is to say, we have 

 doubled the circulating electricity, and consequently the 

 consumption of zinc, and also doubled the heat. 



Here then, again, the theory is consistent with itself, and 

 we may accept it as partially true when the circumstances 

 do not vary more than in the manner we have described. 

 That is to say, in some cases the theory is partially true, and 

 it will be found that the general theory itself has been 

 erroneously deduced from an experimental examination of 

 such particular cases. I say partially true, because we have 

 as yet spoken only of the total heat produced, but not of its 

 distribution in the various parts of the circuit. Further on 

 I think it will appear that the laws which are supposed to 

 regulate this distribution are not true, except in particular 

 cases. 



7. But now let us vary the circumstances in another 

 manner. 



Take a galvanic couple of (say) zinc and platinum, having 

 an electro-motive force, E, a battery resistance, R6, and a 

 conducting wire with a resistance, rw. Then, as before — 



E V,^, . y E 2 



rw] 



H = pR=f E Y(Rb + 

 \Rb-\-rwJ 



\Rb J r rwJ Rb-\-rw 



Next, instead of the single galvanic couple of zinc and 



