UNPUBLISHED FRAGMENTS. 429 



The meagreness of the results obtained in my E.H.S. in the matter 

 of electrolysis has a deeper reason than the difficulty of the evaluation 

 of the potentials. 



In the first place, cases of true equilibrium (even for open circuit) 

 are quite exceptional. Thus the single case of unequal concentration 

 of the electrolyte cannot be one of equilibrium since the process of 

 diffusion cannot be stopped. Cases in which equilibrium does not 

 subsist were formally excluded by my subject, and indeed could not 

 be satisfactorily treated without the introduction of new ideas quite 

 foreign to those necessary for the treatment of equilibrium. 



Again, the consideration of the electrical potential in the electrolyte, 

 and especially the consideration of the difference of potential in 

 electrolyte and electrode, involves the consideration of quantities of 

 which we have no apparent means of physical measurement, while 

 the difference of potential in "pieces of metal of the same kind 

 attached to the electrodes" is exactly one of the things which we" can 

 and do measure. 



Nevertheless, with some hedging in regard to the definition of the 

 electrical potential, we may apply 



V*-V f = a a (p a '-pS) 



to points in electrolyte (') and electrode ("). 

 This gives 



say, rvr 



The G like the P of your formula seems to depend on the solvent, 

 presumably varies with the temperature, but as Nernst remarks does 

 not depend on the other ion associated with (a), so long as the solution 

 is dilute. 



The case of unequal concentration, or, in general, cases in which 

 the electrolyte is not homogeneous, I should treat as follows ; Let us 

 suppose for convenience that the cell is in form of a rectangular 

 parallelepiped with edge parallel to axis of x and cross section of unit 

 area. The electrolyte is supposed homogeneous in planes parallel to 

 the ends, which are formed by the electrodes. 



Of course we should have equilibrium if proper forces could be 

 applied to prevent the migration of the ions and also of the part of 

 the solutum which is not dissociated. What would these forces be ? 

 For the molecules ( 12 ) which are not dissociated, the force per unit of 



mass would be C ^. (The problem is practically the same as that 



CttK/ 



discussed in E.H.S. [this volume], pp. 144 ff.) If the unit of mass of 



