Potential of Electrodes in Stationary Liquids. 39 



Proceeding on the first plan, we have the equation* 



c=( -'-Wi> 0) 



in which C ( , is the original concentration of the substance 

 electrolysed, C its concentration after the time t, k its dif- 

 fusion coefficient, and F the amount removed by electrolysis 

 at the electrode ]>er unit of surface and time. 



From this equation we find the following value for the 

 relative change of concentration at the electrode : — 



G.-C 2F /T 



Proceeding according to the second plan and indicating the 

 distance from the electrode at which no change of concen- 

 tration takes place by 3, we have the following relation 

 according to Fick's diffusion law : — 



L-fc g , 



from which we obtain for the relative change of concentration 

 at the electrode the value 



oT = «X (3) 



When the current is employed solely for reduction we have 



F =%540'- •••••• W 



concentrations being expressed in g. -equivalents or mg.- 

 equivalents per c.c, and current-densities in amperes per 

 sq. cm. or milamps. per sq. cm. respectively. 



In order to eliminate k from these equations we may cal- 

 culate its value from the experiments we have described in 

 the present paper. For this purpose we must assume that 

 nitrobenzene has been completely removed from the electrode 

 bv reduction to azoxybenzene when hydrogen is evolved. 

 AVe then find k by applying equations (1) and (4) to our 

 experiments. We thus obtain 



/:= (%5iUC ') 77> (5) 



quantities referring to our experiments being distinguished 

 * Sand, lor. < it. p. o-">. 



