198 



WORK OF P. B. DAVIS. 



and ammonium iodide over the range of dilution studied. That the increase in 

 fluidity is not exactly proportional to the concentration, may be due to the slight 

 increase in ionization in the more dilute solution , the effect of the anions tending to 

 offset that of the cation. 



Table 141 shows the viscosities and fluidities of rubidium bromide and ammonium 

 iodide in glycerol-water mixtures at 25, 35, and 45. The addition of water to 

 glycerol causes an enormous increase in fluidity. The curve representing the fluidity 

 changes with decreasing percentages of glycerol is strikingly similar to the conduc- 

 tivity curves in those mixtures. 



11.3 2 4 10 



Volume Concentration 

 Fig. 85. Conductivity and Fluidity of Ammonium Iodide in Glycerol at 25 e 



The salts studied show negative viscosity in the glycerol-water mixtures and in 

 pure water at low temperatures. In water at 45, rubidium bromide shows a ten- 

 dency to pass over to positive viscosity, although the transition is not very marked. 



The last table (144) gives a comparison of the percentage increase in fluidity pro- 

 duced by normal solutions of the two salts in glycerol-water mixtures at 25. The 

 values do not follow the law of averages in such mixtures, but are lower. This is in 

 all probabilitjr due to the increased ionization in the mixed solvents, and also to 

 the breaking down of the molecular complexes of the solvent, which would in both 

 cases give ultimate particles with greater frictional surfaces. 



