Hypothesis of Ionic Dissociation. 4G5 



this support completely and leaves the matter, so far as the 

 ionic dissociation hypothesis is concerned, in a state of 

 extreme confusion. The strength of acids should not, ac- 

 cording to the new point of view, be proportional to their 

 hydrogen ion concentration and it will be interesting to see 

 if ionists will turn their backs on their old friend and admit 

 that this is the case. 



The close connexion that undoubtedly exists between 

 -chemical and electrolytic activity is in all probability due to 

 their both being manifestations of the same process: in other 

 words, the passage of a current through a solution of an 

 electrolyte is conditioned by chemical action and chemical 

 miction itself is an electrolytic process. Perhaps the ionists 

 will now find a loophole of escape in the admission that ions 

 and undissociated molecules may both be concerned in con- 

 veying an electric current but this would obviously be a 

 suicidal step. It is highly interesting, however, that the 

 possibility of this being the case has recently been put 

 forward by G. N. Lewis*. 



The granting of a franchise to the non-ionized molecules, 

 so allowing them as well as the ions to partake directly in 

 chemical change, places a further obstacle in the path of the 

 ionists. It will necessitate serious alteration of the beauti- 

 fully simple explanation they have given of chemical action 

 occurring in solutions of electrolytes: as, for instance, of the 

 processes involved in qualitative analysis. Ions alone were 

 ■supposed to be directly involved in the interactions and pre- 

 cipitation was explained as due to the combination of ions 

 derived from different interacting molecules to form undis- 

 -sociated molecules of a new type, relatively insoluble in 

 water. Nothing more was involved than dissociation into 

 ions and recombination of the latter to form the various 

 possible molecular species. In the case of molecules that 

 'can interact without being first dissociated, another type of 

 action must be postulated. The ionists must, in fact, accept 

 for the non-dissociated molecules the view of their opponents, 

 that association of the interacting molecules precedes the 

 chemical interchange of radicles. Thus, for interactions in 

 solutions of electrolytes, we shall have to assume two diame- 

 trically opposite kinds of chemical change occurring simul- 

 taneously, one in which dissociation and another in which 

 association of the involved molecules is the first step. The 

 weakness of such an explanation is only too obvious. 



The supporters of the ionic dissociation hypothesis are thus 

 .apparently faced with serious difficulties if they accept the 

 * Joura. Amer. Cliem. Soc. xxxiv. p. 1642 (1912). 



