Galvanic Pile, and Electromotive Forces. 437 



From the foregoing it follows without doubt that it is very 

 difficult to employ the mode of representation No. 1 for the 

 explanation of the thermal phenomena which take place in 

 the galvanic pile and its circuit. Even if we leave out of con- 

 sideration that it is by no means easy to understand in what 

 manner the heat is conveyed from the pile to the different con- 

 ductors outside of it, it may yet be truly said that it has been 

 attempted to attribute the difference between the amounts of 

 the chemical and the galvanic heat to causes whose presence 

 cannot with any certainty be proved, and the actions of which 

 are still less determined quantitatively. It appears to me 

 that such a way of explaining cannot, from a scientific 

 point of view, be called a good one. The question takes ano- 

 ther form when representation No. 2 is employed. The as- 

 sumption that the electromotive force expends a certain quan- 

 tity of vis viva or heat to produce the work of the current is 

 fully justified, because it is valid also for forces different in 

 nature from the electromotive. That the consumption of heat 

 by the electromotive force must be equal to the production of 

 heat by the current is self-evident ; yet it does not* by any 

 means necessarily follow that this heat-consumption is exactly 

 equal to the quantity of heat which is generated by the chemi- 

 cal processes in the pile. 



Employing representation No. 2, the experiments cited in 

 the foregoing show that the heat-consumption occasioned by 

 the electromotive force in the zinc-platinum and cadmium- 

 platinum piles with hydrochloric acid for the electrolytic liquid, 

 is greater than the heat-production brought about by the che- 

 mical processes which take place in these piles, but that the 

 ratio in the Smee pile is inverse. It is easy to understand 

 that the consumption of heat, and consequently also the quan- 

 tity of galvanic heat in the entire circuit, in the Smee pile, 

 must be less when the external resistance is diminished. The 

 negative platinum disk in this pile is polarized by hydrogen ; 

 and when currents so feeble as those which occur in these ex- 

 periments are in question, the polarization increases with the 

 intensity of the current. Therefore, when the external resist- 

 ance is little, the electromotive force of the polarization musi 

 be relatively great, and consequently the total electromotive 

 force of the pile become inconsiderable. It is therefore evi- 

 dent that the heat-consumption of this force, and consequently 

 also the galvanic heat developed by the current, must dimi- 

 nish with the resistance. We have therefore no need to have 

 recourse to unknown causes in order to account for the results 

 obtained by the experiments instituted. 



4. For determining indubitably which of the two repre-* 



