Theory of Electrolytic Dissociation. "227 



readily coagulated by substances which lower the vapour- 

 tension greatly, and that their coagulating power stands in 

 relation to their ability to lower the vapour-tension ; but this 

 coagulating power has nothing to do with electrolytic con- 

 duction. From the vapour-tension of a solution no one can 

 predict whether that solution will conduct electricity or not, 

 much less tell how well it will conduct. This statement is 

 fully warranted by the facts as known at present. 



Many salts are very good electrolytes when in the molten 

 state: others are poor conductors, and still others are insulators. 

 From the views just advanced, it is clear that it is perfectly 

 correct to consider electrolytic solutions and fused electrolytes 

 together : for conducting solutions are electrolytes which are 

 in a fused condition at ordinary temperatures. Faraday 

 selected the experiment in which a current is passed through 

 fused silver chloride between two silver electrodes as repre- 

 senting the simplest case of electrolysis ; for here there are but 

 two chemical elements involved, and yet all the phenomena 

 accompanying electrolysis are here exhibited. Who would 

 question the correctness of this view? The theory of elec- 

 trolytic dissociation has led Whetham to consider the case of 

 i'used electrolytes as entirely different from that of electrolytic 

 solutions, a position which is clearly not warranted by experi- 

 mental facts. 



Take water and pure acetic acid. Both are very poor con- 

 ductors. Add a little water to some of the acid ; and again 

 add a little acid to some of the water. In both cases the 

 resulting solutions conduct. Now is it the acid that con- 

 ducts in the water, or is it the water that conducts in the 

 acid? Years ago it was customary to say that we acidulate 

 the water to make it conduct better ; now it is fashionable 

 to say that it is the acid which in the dissociated state conducts 

 in the water, the latter serving merely as a medium in which 

 the ions of the acid may exist and migrate. Furthermore, 

 the original conductivity of the pure water is frequently 

 deducted from that of the solution, in order to determine the 

 conductivity of the acid. As a matter of fact, however, it is 

 the combination of the acetic acid and water that conducts. 

 The water has just as much to do with the conduction as the 

 acid, and it is absurd to subtract either the conductivity of 

 the water or that of the acid from the conductivity of the 

 solution. But the calculation of the molecular conductivity 

 is founded upon the supposition that the solvent plays no part 

 in the conduction. This supposition being untenable, it 

 follows that the comparison of the molecular conductivities 

 at different concentrations is a process which is quite 



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