KAHLENBERQ — THEORY OF ELECTROLYTIC DISSOCIATION. 345 



changes of concentration that take place around the electrodes 

 in the electrolysis of non-aqueons solutions promises to yield re- 

 sults of unusual interest, especially as bearing upon the value 

 of the dissociation theory in interpreting electrolytic phenomena. 

 Since the time when Hittorf 1 determined the migration numbers 

 of Cdl 2 , Znl 2 and ZnCL in absolute alcohol and those of Cdl 2 

 in amvl alcohol, this field has not been cultivated. Now we 

 know of a number of fairly good and some cases of excellently 

 conducting non-aqueous solutions, in which the migration num- 

 bers await determination — work begun in this laboratory. 



It might not be superfluous to recall in connection with the 

 claim that thermodynamics requires the dissociation theory, that 

 Clausius, who showed the discrepancy between the Grotthus the- 

 ory and thermodynamics, did not find it necessary to put forth 

 such a radical hypothesis as that of Arrhenius. Again, Hittorf 

 on the basis of his studies of the migration of the ions evidently 

 did not think it necessary to frame a theory giving the term ion 

 the meaning that it now has. Finally let the reader try to re- 

 call any real marked improvements or discoveries in the realm 

 of electrolysis which are directly traceable to the influence of the 

 dissociation theory. The function of E. M. F. in electrolysis, 

 especially in electrolytic separations, has been more strongly em- 

 phasized, but that is really about all. The importance of cur- 

 rent density was early pointed out by Bunsen, and as far as the 

 influence of the temperature of the electrolyte upon the mechan- 

 ical and chemical character of the deposit is concerned, we are 

 still upon an empirical basis as before. It is very significant, 

 for instance, that in the latest edition of his work on quantita- 

 tive analysis by electrolysis, Classen has devoted about four 

 pages of the introductory part of the book to the ionic theory, 

 and after that in the main body of the book we read nothing 

 more of that theory ; the preparation of the solutions from which 

 to get suitable deposits is very much upon the same empirical 

 basis as ever. And it is also safe to say that electrolysis as 

 used in the arts has not received much help from the theory of 

 Arrhenius. 



»L c. 



