ELECTROLYTIC DISSOCIATION 41 



conduct, while fused silver iodide does, which is an anomaly. 

 Arrhenius finds an explanation in the dissociation of silver 

 iodide by heat. 



2. Hydrochloric, hydrobromic and hydriodic acids differ 

 markedly in stability, but they are all assigned the same 

 dissociation ratio. This is evidently a case of misapprehen- 

 sion, as the instability lies in the negative ion itself, and not 

 in the compound. 



3. Why does not alcohol dissociate electrolytes as well as 

 water, and why does not water conduct? 



4. According to Ostwald's measurements, phenylpropionic, 

 cinnamic, and phenylpropiolic acids range in the order of 

 their conducting power, 



C6H 5 .C.C.COOH>C ft H 5 .CH.CH.COOH>C fl H 5 .CH 2 .CH 2 .COOH. 

 Therefore that acid is most dissociated which can least spare 

 its hydrogen. 



This argument illustrates the necessity of keeping the 

 types of reactions apart. Nothing appears to justify his as- 

 sumption that the carboxyl group should be affected in this 

 way by what happens in a neighboring group, where hydro- 

 gen plays an entirely different role. 



The main opposition to the dissociation hypothesis is to 

 be found in a rival hypothesis which has found advocates 

 in Mendeleeff, Armstrong, Pickering, Crompton, Bonty and 

 E. Wiedemann, the"hydration" hypothesis connected with 

 the "residual affinity" idea. Bonty holds that electrolytes are 

 of two classes, those in which both ions show equal rates of 

 transference, and the "abnormal" ones, in which this is not 

 the case. All abnormal salts are said to be capable of form- 

 ing hydrates and do so. The law of equivalent ratio holds 

 absolutely in so few cases that these considerations may 

 be dismissed, in view of the more powerful ideas of Kohl- 

 rausch. E. Wiedemann argues from the change of color of 



