occasioned by Differences of Concentration. 349 



by which (1— n) of the cation at the cathode becomes free — 

 which, combined with the amount n of cation brought to this 

 sirle, gives the quantity 1 set free at the cathode. In like 

 manner the quantity n of the cation is conveyed away from the 

 other side, by which n of the anion is set free. To this is added 

 (1— n) of the anion brought over. Now, when the cation is a 

 metal which can deposit itself on the electrode, (1 — ??.) of the 

 metal disappears there from the solution, and (1 — n) of the 

 salt-forming acid is conveyed away ; consequently from there 

 (1 — n) of the salt is removed. On the other side the liberated 

 anion combines with the metal of the electrode ; and therefore 

 1 equivalent of new metal here enters the solution, while n of 

 the metal is carried away and (1 — n) of the anion is brought 

 over. This gives here an increase of the quantity of the salt 

 by (1 — n) of the equivalent for the unit of time and unit of 

 current. If the metal of the electrode is the same as that 

 which is contained in the solution, the total result of the elec- 

 trolysis is the same as if one equivalent of metal were carried 

 from the anode to the cathode, and (1 — n) equivalent of salt 

 in the solution from the cathode to the anode. 



If, then, the salt-solution is more concentrated at the cathode 

 than at the anode, the difference of concentration is equalized 

 by the transfer. Therewith the liquid approaches the state of 

 equilibrium to which the forces of attraction between the water 

 and salt tend even in the processes of diffusion, namely the 

 state of uniform distribution of the salt. Thus the chemical 

 forces acting in this direction will also in turn assist the elec- 

 tric current acting in their direction. 



That the work of the chemical forces which herewith comes 

 in acts in this case as an electromotive force according to the 

 same laws as other electrolytic chemical processes, can be de- 

 duced from the mechanical theory of heat. 



A reversible process without changes of temperature, such 

 as is required for the application of Carnot's law, we can in- 

 stitute in the following manner: — 



(1) We let the quantity E of positive electricity slowly enter 

 the anode in a constant current, and in return take away the 

 quantity + E from the cathode ; or, what leads to the same 

 result, we admit + J E into the anode, and, inversely, discharge 

 — JE at the cathode. If V k and P a are the values of the elec- 

 trostatic-potential function for the two electrodes, then is 



the work which must be done in order to bring about this 

 through-current. If the duration of the current is equal to t, 

 the current-intensity .according to electrostatic measure is given 

 by the equation j£ = E. 



