THE CONDUCTANCE OF SOLUTIONS VISCOSITIES 



113 



potassium iodide at 0, 30, and 60 and sodium chloride at 10, 30, and 

 60. It will be observed that the viscosity in the case of potassium 

 iodide at passes through a minimum in the neighborhood of 2% nor- 

 mal, after which it again increases. At higher temperatures the minimum 

 is displaced toward lower concentrations and finally disappears. The 

 negative viscosity effect decreases rapidly with increasing temperature 

 and in most cases disappears in the neighborhood of 30. At still higher 

 temperatures the viscosity effect becomes positive. In general, the posi- 

 tive viscosity effect increases markedly with the temperature. 



2.2 

 2.0 

 1,6 



. 1-6 



o 



X J.4 



I Ii2 



> 



1.0 



0.8 

 0.6 



o.o 



1.0 



4.0 



S.O 



2,O 3.0 



Concentration. 



FIG. 16. Viscosity of Aqueous Solutions at Different Concentrations. 



In glycerine solutions, 7 ammonium iodide, potassium iodide, and 

 rubidium iodide exhibit negative viscosity effects. Lithium chloride, on 

 the other hand, as in water, exhibits a viscosity increase with c increasing 

 concentration. In glycerine solutions, the negative viscosity effect dis- 

 appears in the neighborhood of 75. 



It is obvious that, if the viscosity of a solution changes with concen- 

 tration, the speed of the carriers, to which the conductance of the solu- 

 tions is due, will likewise change with the concentration. If this is the 



case, then the conductance ratio, y = -r-, no longer measures correctly 



AQ 



'Davis and Jones, Ztachr. }. phys. Chem. 81, 68 (1913). 



