Theory of Electrolytic Dissociation. '2'2?> 



fact that with some solvents like alcohol freezing-point work is 

 impossible, is hardly valid, for such solutions may be readily 

 examined by vapour-tension or boiling-point methods. It is 

 true that in operating with many non-aqueous solutions, like 

 liquid ammonia, liquid sulphur dioxide, liquid hydrocyanic 

 acid, special difficulties and dangers present themselves; but 

 these are generally quite surmountable, and indeed often it is 

 fully as easy to investigate a non-aqueous solution as one in 

 which water is the solvent. It simply has not yet become 

 generally fashionable to investigate non-aqueous electrolytic 

 solutions. When this work is taken in hand by more in- 

 vestigators, the fact that the dissociation theory is useless and 

 misleading will gain ground more rapidly. 



It has been argued by some that since the dissociation 

 theory has been developed by use of aqueous solutions, the 

 fact that it cannot explain the phenomena in non-aqueous 

 solutions should not be used against it. It is well known, 

 however, that defenders of the ionic hypothesis have con- 

 tinually sought to support their views by citing some phases 

 of the behaviour of non-aqueous solutions. Thus in trying 

 to find facts to support the Nernst-Thomson rule, in com- 

 paring chemical activity in electrolytes and non-electrolytes 

 and in considering molecular weights in conducting and non- 

 conducting solutions, the behaviour of non-aqueous solutions 

 has always been compared with that of aqueous solutions. 

 By so doing it has been virtually admitted that it is legitimate 

 to apply the dissociation theory to non-aqueous solutions. 

 It is only since the discovery of excellent electrolvtes in 

 solvents other than water, the behaviour of which constitutes 

 a strong argument against the theory, tint objections have 

 been made to testing the theory in the field of non-aqueous 

 solutions. 



But the dissociation hypothesis has been applied even to 

 electrolytes that are not solutions at all ; to fused salts, for 

 instance, to pure solvents, and to gases. The line of thought 

 in this procedure is that, since the electrolytic conductivitv 

 of solutions is assumed to be due to free ions, free ions must 

 occur wherever electrolytic conduction is found. And so we 

 find the idea established that pure substances dissociate them- 

 selves electrolytic-ally without the aid of any solvent whatever. 

 Now since a pure substance may be considered as a solution 

 100 per cent, -trong, it might be well for the advocates of 

 the dissociation theory to pause to consider whether such 

 solutions are sufficiently dilute to warrant the attempt to 

 apply to them a theory which it is admitted holds strictly onlv 

 for infinitely dilute solutions. Even conservative advocates 



