FORM OF THE CONDUCTANCE FUNCTION 103 



ion concentrations, while at higher concentrations it is convex toward 

 this axis; in other words, the experimentally determined points lie upon 

 a curve which has an inflection point somewhere between the concentra- 

 tions given above, probably in the neighborhood of 0.1 normal. Schles- 

 inger is inclined to attribute the deviation of the points in the more 

 dilute solutions to the presence of impurities. So far as the conductance 

 of the solvent is concerned, since sodium formate has an ion in common 

 with formic acid, it is to be expected that the ionization of formic acid 

 itself will be repressed by sodium formate, so that the conductance of the 

 pure solvent itself will not enter. He believes, however, that there are 

 present in the solvent impurities, as a result of which the measured con- 

 ductance is higher than that due to the electrolyte. On the other hand, 

 it is known that the salts of the fatty acids yield ions which move very 

 slowly and whose solutions exhibit an extremely high viscosity. The 

 form of the curve in the case of the formates in formic acid is similar 

 to that of certain acids in water. Further light may be thrown upon 

 this question by considering the conductance curves of salts of organic 

 acids in water, whose solutions likewise exhibit a high viscosity. The 

 lower curve in Figure 15 represents a plot of I/ A against the specific 

 conductances for sodium acetate in water at 18. An inspection of the 

 figure shows at once that the curve for sodium acetate in water is in all 

 respects similar to that of sodium formate in formic acid. Between the 

 concentrations 0.1 and 0.5 normal, the points lie upon a straight line 

 within the limits of experimental error. In the more dilute solutions, 

 the experimentally determined points lie upon a curve concave toward 

 the axis of concentrations and in the more concentrated solutions on a 

 curve convex toward this axis. In the case of sodium formate in formic 

 acid, the concentration interval over which the points lie upon a straight 

 line is 0.0667 to 0.297, corresponding to a concentration ratio of 4.45, 

 while in the case of sodium acetate in water the corresponding concen- 

 tration interval is 0.1 normal to 0.5 normal, whose ratio is 5.0. If we 

 hold that the law of mass-action applies to solutions of sodium formate 

 in formic acid, we might equally well hold that this law applies to solu- 

 tions of potassium acetate in water. Our knowledge of the behavior of 

 aqueous solutions, however, is such that it is at once evident that the 

 linear form of the curve between 0.1 and 0.5 normal is due to the fact 

 that, owing to the high viscosity of the solutions at higher concentra- 

 tions, the conductance as measured is smaller than it otherwise would be. 

 On the other hand, in the more dilute solutions the form of the curve 

 in the case of sodium acetate is entirely similar to that of other 

 binary electrolytes in water. It is difficult, therefore, to escape the con- 



