HETEROGENEOUS EQUILIBRIA 241 



tion of the boiling point increases in the case of all the salts measured. 

 It is obvious that in these solvents the concentration at which the meas- 

 urements were carried out is too high to admit of a comparison with 

 the results of the conductance method. In comparing the results of the 

 conductance method with that of other methods of determining the degree 

 of ionization of salts in non-aqueous solvents, it should be borne in mind 

 that, according to conductance measurements, the deviations from the 

 law of simple mass-action increase greatly as the dielectric constant of 

 the medium decreases. If, then, the deviations from the laws of dilute 

 solutions lead to a lack of correspondence between the results of the 

 osmotic and the conductance methods, the discrepancy between the results 

 of the two methods should be the greater, the greater these deviations. 

 It might be expected, therefore, that, in solvents of low dielectric con- 

 stant, the discrepancies would prove to be very great. 



In solvents of fairly high dielectric constant, molecular weight deter- 

 minations by osmotic methods yield values for the ionization which are 

 comparable with those resulting from conductance measurements, and 

 the ionization increases as the concentration decreases. In making such 

 comparisons, however, it should be borne in mind, not only that the ex- 

 perimental errors are great in the osmotic determinations, but, also, that 

 the conductance values are more or less uncertain, and that the values 

 of A are often subject to considerable errors. In the following table are 

 given values of the ionization Y C as determined from conductance meas- 

 urements and Y as determined from the elevation of the boiling point 

 for solutions of (C 2 H 5 ) 4 NI in a number of solvents. 11 



TABLE XC. 

 VALUES OF i FOR SOLUTIONS IN DIFFERENT SOLVENTS. 



CH 3 OH CH 3 CN 



V 3 6 12 V 10 15 



T c 0.38 0.45 0.52 YC 0.48 0.54 



y b 0.24 0.29 0.38 y& 0.49 0.57 



C 2 H 5 OH C 2 H 8 CN 



V 30 V 30 



Y c 0.41 Y C 0.53 



Y 6 0.30 Y& 0.54 



"Walden, Zttchr. }. phys. Chem. 55, 281 (1906). 



