148 



WORK OF M. R. SCHMIDT. 



In the solutions of cobalt chloride in ethyl alcohol, negative temperature coefficients 

 of conductivity occur. These have also been noticed by Jones and McMaster in 

 certain solutions of the same salt in mixtures of acetone and the alcohols. In the 

 present case the temperature coefficient of the tenth-normal solution is positive, though 

 very small, and in the fiftieth-normal solution it becomes negative. The temperature 



coefficients reach a minimum in the hundredth-normal 

 solution, and then increase regularly, again becoming posi- 

 tive in the dilute solutions. Temperature coefficients of 

 conductivity in ethyl alcohol are always small, and it is 

 known that the degree of ionization decreases with rising 

 temperature. We have already proved that cobalt chlo- 

 ride in ethyl alcohol has a strong tendency to polymerize. 

 The occurrence of negative temperature coefficients of con- 

 ductivity, therefore, shows that the decrease in ionization 

 due to rise in temperature, is more than sufficient to over- 

 come the effect of increased ion velocity brought about by 

 increased fluidity. 



In the mixed solvents the temperature coefficients of 

 conductivity in no case follow the law of averages, but, 

 like the conductivities, are always less than the calculated 

 values. 



We have thus shown that for solutions in mixtures of 

 glycerol with water or the alcohols, the molecular con- 

 ductivities are always less than the averages calculated 

 from the conductivities in the component solvents. Hence, 

 we may conclude that glycerol is a solvent which, when 

 mixed with another, gives a mixture whose properties are 



not additive, and in 

 this respectglyceroi re- 

 sembles water. In the 

 three cases tested 

 glycerol causes some 

 change in the state of 

 molecular aggregation 

 of the other solvents, 

 producing mixtures 

 similar, in many ways, 

 to mixtures of water 



Per cent. Glycerol 



Fig. 68. Conductivity of Potassium Iodide in Glycerol-Methyl 



Alcohol at 25. 



with the alcohols or 



acetone. We can now 

 proceed to show that the departure from the law of averages is just as pronounced 

 when we examine the fluidities of the mixtures of glycerol. 



VISCOSITY AND FLUIDITY. 



Tables 111 to 114, inclusive, give the viscosities and fluidities of the pure solvents, 

 the mixed solvents, and the tenth-normal solutions of the three salts in these liquids. 



