288 Mr. "\Y. C. D. Whetham on the 



further experiments have been made, it is impossible to sav 

 wh ether or not the first relation suggested by the dissociation 

 theory hold- for non-aqueous solutions. In fact, however 

 great be the likelihood of the general similarity of all con- 

 duction in solutions, we have not sufficient knowledge of 

 electrolysis in non-aqueous media to conclude that the 

 nature of the process is the same as in aqueous solution. It 

 is not yet certain that we can here apply Faraday's laws, 

 Ohm's law, and Kohlrausch's theory of ionic velocity, 

 though, for alcoholic solutions, a certain amount of evidence 

 in favour of this view has been accumulated. 



The second relation enunciated by Arrhenius suggests that, 

 when the dissociation is incomplete, the coefficient of ioniza- 

 tion measured electrically should agree with the value calcu- 

 lated from the osmotic effects ; but, as we have seen, such 

 a relation can only hold for certain cases, and then only 

 within very narrow limits of concentration. In order to 

 obtain a valid basis for exact comparison with eryoscopic 

 determinations, it is necessary to measure the electrolytic 

 conductivities at the freezing-point. When this is done, it 

 is found that the two values of the ionization, though they 

 approach each other with decreasing concentration, only 

 actually coincide at the most extreme dilution reached in the 

 eryoscopic experiments. Thus, in a full discussion of the 

 subject which will be found in a treatise on the ' Theory of 

 Solution ' lately published by the present writer, it is shown 

 that the disturbing causes we have indicated become appre- 

 ciable at concentrations considerably smaller thau hitherto 

 believed : but it is now evident that the discrepancies that 

 then arise are not conclusive evidence against the general 

 truth of the explanations advanced by the dissociation theory. 

 Such discrepancies merely afford useful information about 

 the nature of the disturbing influences, and about the value 

 of the concentration at which the>e influences begin to be 

 appreciable. 



Passing as before to solutions in solvents other than water, 

 we again find the phenomena more complicated, even if the 

 general nature of the conduction should prove to be the same 

 as in aqueous solutions. Complex ions seem to be common, 

 and other disturbing factors appear to be present. Kahlen- 

 berg has called attention to cases in which the boiling- or 

 freezing-points of conducting solutions indicate molecular 

 weights equal to or greater than the normal, and this suggest- 

 that no dissociation occurs. Until the specific ionic mobilities 

 in these solvents are known, we have no means of estimating 

 what percentage ionization is required to give the observed 



