98 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



but from the data for solvents of somewhat higher dielectric constant 

 it may be inferred that the transference numbers are approximately 

 normal. Furthermore, since it appears that the deviations from the 

 mass-action law in aqueous solutions are of the same character as in 

 non-aqueous solutions, it follows that similar intermediate ions would 

 have to be assumed to be present in solutions of the strong binary elec- 

 trolytes in water. If such were the case, not only should the trans- 

 ference numbers be abnormal, but they should vary as a function of the 

 concentration. Now, while it is true that many transference numbers 

 do vary with the concentration, a considerable variation takes place only 

 at relatively high concentrations, and only at such concentrations where 

 the viscosity of the solution has increased sufficiently to materially affect 

 the motion of the ions through the solution. It would seem that trans- 

 ference measurements should yield data corroborating this last hypothesis 

 if it were correct. So far as available data are concerned, the hypothesis 

 is not substantiated. 



4. The Form of the Conductance Curve in Dilute Aqueous Solu- 

 tions. The applicability of the conductance function to aqueous solu- 

 tions is uncertain. That the Storch equation holds approximately for 

 aqueous solutions at higher concentrations has long been known. In 

 the case of Equation 11 this would yield for m values of approximately 

 0.5, and for D values in the neighborhood of 2. With such large values 

 of the constant D and small values of the constant m, it becomes 

 very difficult to determine the value of the constant K. At concentra- 

 tions sufficiently low, so that the effect of the D term might be neglected, 

 the ionization is so nearly complete that it becomes practically impos- 

 sible to demonstrate whether or not the mass-action law is approached 

 as a limiting form. Kraus and Bray have shown that Equation 11 may 

 be applied with considerable exactitude to solutions in water up to 10~ 3 

 normal, provided a value of A is chosen which is lower than the experi- 

 mentally determined values of the equivalent conductance at very low 

 concentrations. More recently, Washburn and Weiland 21 have con- 

 cluded from their very accurate conductance measurements on KC1 up 

 to 2 X 10~ 5 normal that the mass-action law is actually approached as 

 a limit. Their results, however, do not appear to be conclusive, since, 

 in extrapolating for the value of A , they assume the mass-action law 

 to hold. 22 If the mass-action constant is calculated with a value of A 

 based on the assumption that the mass-action law holds, then the results 

 must necessarily conform to the assumption made. The curve obtained 



"Washburn and Weiland, J. Am. Cher*. Soc. W, 106 (1918). 

 Kraus, J. Am. Cfhem. Soc. 4%, 1 (1920). 



