MR. S. W. J. SMITH ON THE NATURE OF ELECTKOCAI'ILL.MtY NIKM i\ll IN A 51 



in which the integral represents the quantity of electricity that has passed in tin- 

 circuit during the time r taken by the system to acquire its steady state. Also 



IT = IT, 

 if 



1 f T 

 = (IT, ir n ) I i (It 



C| Jo 



and 



IT" = i dt ir = IT'. 



c, .' 



N"\v if the condenser A A' is very large comjKired with the condenser 1515. \\e nuiy 



neglect in comjKirison with , so that we get 

 c, c^ 



it 



IT = IT, 1T n 



and 



t 



7T ^~ 7T 7T n 



Thus the effect of introducing the E.M.F. ir t is that the potential difference at the 

 small condenser is changed from IT* to ir, TT,, while the change at the large 

 condenser is negligible. 



If the supj>osed analogy were complete, we should, therefore, have the result that 

 in the capillary electrometer the variation of the potential difference at the capillary 

 electrode is the same as the variation of the E.M.F. applied between the terminals. 

 The analogy between the condenser system and the electrolytic cell cannot, however, 

 be complete. In the latter case the original potential difference (corresjw Hiding to 

 ir.) is not arbitrary, but represents one of the conditions of the equilibrium at tin- 

 electrode. Any cause which tends to alter the "natural" potential difference IT., at 

 the small electrode the nature of the solution in the neighlxmrhood of the elect r< '(It- 

 remaining sensibly constant must in general be accompanied by a "depolarization" 

 current representing the continual tendency of the " polarised " electnxle to revert to 

 the original potential difference. We cannot, therefore, have i = in the final steady 

 state ius in the condenser system. 



The E/ect of Depolarization. 



It' we assume, however, that the effect of the depolarization Is to produce a fall i>t' 

 potential within the electrolyte according to Ohm's law, the nature and magnitudi- 

 of the effect can be readily specified. Thus, taking the symlM.ls ;) s alxi\e to In- 

 appli.-ahl.- t.. tin- capillary electrometer, we shall have 



r.- = B'./(") 



and 



TT'-TT" = 11. 

 II _' 



