WORK OF M. R. SCHMIDT. 



149 



The fluidities of the solutions are, as usual, in nearly every case less than those of the 

 corresponding solvents. In three solutions, however, we have the phenomenon of 

 negative viscosity. These are potassium iodide in water, and in 25 and 50 per cent 

 glycerol and water, at both 25 and 35. An explanation of negative viscosity has 

 been given by Jones and Veazey. 1 It is interesting to find that the fluidity of even 

 so immobile a liquid as 50 per cent glycerol and water is increased by the addition 

 of potassium iodide. In the 75 per cent mixture the viscosity coefficient is again 

 positive, but the difference between the viscosity of the mixture and of tenth-normal 

 potassium iodide in it is not great. The salt does not lower the viscosity of pure 

 glycerol, nor of any of the other solvents used. 



Table 111. Viscosity and Fluidity of Solutions in Mixtures of Glycerol and Water at 25 and 35. 



Solution. 



Water. 



v 25 7j 35 c 



<I>25 C 



* 35 T. C. * 



25 per cent glycerol and water. 



7/25 



t? 35 <1>25 <J>35 C 



T. C. * 



LiBr... 

 CoCl 2 . . 

 KI 



Solvent . 



LiBr.... 

 CoCl 2 ... 

 I.K 



Solvent . 



0.009011 0.00723 

 0.009209 0.00745 

 0.008847 0.00719 

 0.00891 0.00720 



110.99 138.33 0.0246 



108.58! 134.26: 0.0237 



113.02 139. 06 1 0.0231 



112.25 138.89 0.0237 



50 per cent glycerol and water. 



0.0437 

 0.0438 

 0.0425 

 0.0438 



0.02064' 0.01552 48.45 l 64.44 



0.02156 0.01624 46.49 61.65 



0.0199l| 0.01509 50.23 66.25 



0.02003 0.01518 49.91 65.86 



0.0330 

 0.0326 

 0.0319 

 0.0319 



75 per cent glycerol and water. 



0.0656 

 0.0638 

 0.0639 



Table 112. Viscosity and Fluidity of Solutions in Mixtures of Glycerol and Ethyl Alcohol 



at 25 and 35. 



But if we examine the viscosities of the solutions in pure glycerol, we see that the 

 effect of the several salts on the viscosity of the solvent is in inverse ratio to the mo- 

 lecular volumes of the salts. Potassium iodide, with the largest molecular volume, 

 increases the viscosity of glycerol less than does lithium bromide, which has a slightly 

 smaller molecular volume. The latter salt, in turn, increases the viscosity of glycerol 

 much less than does cobalt chloride, which has much the smallest molecular volume 



'Amer. Chem. Journ., 37, 405 (1907). 



