218 Prof. L. Kahlenbero- on th 



& 



ie 



Gefrierpunkts-depression durchaus nicht als absolut streng 

 giiltige Naturgesetze aufgestellt, sondern als nahezu zutreff- 

 ende Erfahrungssatze, welche fur die Zwecke der Molekular- 

 oewichtsbestimmiino- oenau genus: sind.' " 



The molecular conductivity increases with the volume in 

 very many cases; but in some instances, like that of the 

 caustic alkalies, the molecular conductivity first increases and 

 then decreases with increasing volume. In still other cases, the 

 molecular conductivity diminishes or remains practically con- 

 stant as the volume increases. The only cases which conform 

 to the requirements of the dissociation theory, even in general 

 trend, are those in which the molecular conductivity increases 

 with the volume. Specific illustrations are given in the 

 article cited above. The molecular conductivity at any 

 volume v is expressed by the equation A,=CxV, where C 

 is the specific conductance of the solution, /. e. the reciprocal 

 of the resistance of a cube of the solution having an edge of 

 one centimetre, and V is the volume in which one gramme- 

 molecule is contained. Now, as the specific conductance of 

 a solution always diminishes as the solution is diluted, it is 

 clear that in order that A B may increase as the solution is 

 diluted, the increase of the factor V must outweigh the dimi- 

 nution of C. If C diminishes in the same ratio in which V 

 increases, A v remains constant ; and if C diminishes more 

 rapidly than V increases, A P will decrease as the volume 

 becomes greater. As already stated, examples of all three 

 cases are well known in practice. 



It has been contended that it is the high specific inductive 

 capacity of the solvent that causes electrolytic dissociation. 

 To demonstrate this, there are usually cited a few cases like 

 benzene, chloroform, alcohol, and water, in which solvents, to 

 be sure, the conductivity of solutions increases as the dielectric 

 constant increases. However, in a series of articles pub- 

 lished in the c Journal of Physical Chemistry/ Schlundt and 

 I have pointed out a goodly number of cases where solutions 

 in solvents of low dielectric constant are better conductors 

 than solutions in solvents with higher dielectric constants. 

 Similar instances are constantly multiplying, now that 

 methods of measuring specific inductive capacities have been 

 simplified and perfected. In the face of the fact that 

 numerous exceptions to the Nernst-Thomson rule are known, 

 and that no quantitative relation between the conductivity of 

 a solution and the dielectric constant of its solvent has ever 

 been established, it would appear that the Nernst-Thomson 

 rule is really untenable. 



Liquid hydrocyanic acid has a dielectric constant of about 



