VISCOSITY MEASUREMENTS. 



149 



By studying the temperature coefficients we see that we have to deal with a 

 peculiar phenomenon. In the pure acetone, as already stated, we have 

 negative temperature coefficients. In the 75 per cent mixture of acetone and 

 methyl alcohol, beginning with v = 400, we again have negative temperature 

 coefficients. For v = 100 we have the temperature coefficients positive, while 

 at v = 200 we have practically no temperature coefficient of conductivity. 



Tables 71 and 72 (figs. 72 and 73), for cobalt chloride in mixtures of acetone 

 and ethyl alcohol, give a maximum in conductivity in the 25 per cent mix- 

 ture, especially at high dilutions. 



In the mixtures of acetone and ethyl alcohol we have negative temperature 

 coefficients, not only in the pure acetone and 75 per cent mixture, but also in 

 the 50 per cent mixture. In the case of acetone and methyl alcohol, the tem- 

 perature coefficients were negative only in the pure acetone and 75 per cent 

 mixture. With increase of dilution we have an increase in value of the temper- 

 ature coefficients, not only in the pure solvents, but also in the mixtures. 



1002 



Percentage of Methyl Alcohol 



FIG. 67. CONDUCTIVITY OF COBALT CHLORIDE IN MIXTURES 

 OF METHYL ALCOHOL AND ETHYL ALCOHOL AT 25. 



