SODIUM ACETATE. 53 



Only in the 75 per cent mixture is there any regularity observed. Here the 

 (apparent) molecular conductivities increase with decreasing concentration. 



In the pure solvent the conductivities are so small as to be almost neg- 

 ligible. This is not surprising. Wakeman * has determined the conductivity 

 of hydrochloric acid in acetic acid, and has found it to be exceedingly small. 

 For example, for v = 98.56 /><. was found to be 1.78. 



The irregular results in mixtures of acetic acid and water are to be ex- 

 plained as being due to mutual isohydric influence of dissolved substance 

 and solvent. The dissociation of the sodium acetate is driven back by the 

 acetic acid, and vice versa. This influence is most marked where the disso- 

 ciation of each separately would be greatest, i.e., in mixtures of lower per 

 cent of acetic acid, and of minimal concentration of sodium acetate. 



Since these phenomena have no direct connection with the problem in hand, 

 no further discussion is necessary, especially as the question has been treated 

 by Wolf 1 and by Riidorff . 2 



DISSOCIATION IN FIFTY PER CENT METHYL ALCOHOL. 



It has been seen that in the case of hydrochloric acid in mixtures of methyl 

 alcohol and water, limiting values for conductivity are reached at a smaller 

 dilution than in either water or methyl alcohol. It is important to see whether 

 this relation is general. 



The limiting values in the case of sodium and potassium iodides and potas- 

 sium bromide were determined. Throughout this part of the work the 

 utmost care was taken in the preparation of solvents and solutions, and in 

 making the dilutions. The cells used were standardized before and after each 

 series of measurements. The conductivity of the solvent was carefully deter- 

 mined, and the necessary corrections were made. The water and the methyl 

 alcohol used had a conductivity of not over 1 x 10~ 6 . Every result given is 

 the mean of from five to ten different values. 



POTASSIUM IODIDE. 



The potassium iodide was prepared by Kahlbaum. The flame test showed 

 that no appreciable impurity was present. The salt was dried to constant 

 weight at 100 to 110. The values obtained are given: 



The value for the conductivity at v = 400 agrees with the (interpolated) 

 value obtained by Zelirisky and Krapiwin, and our results may therefore be 



'Ztschr. phys. Chem., 15, 181 (1894). 2 Loc. cit. 



