WORK OF M. R. SCHMIDT. 



151 



increase in the fluidity of the pure solvent. This relation does not hold for all of 

 the temperature coefficients of fluidity, but the exceptions are not many, and it 

 would seem that an explanation such as the above is at least partially correct. 



A comparison of the conductivity and fluidity curves shows, 

 then, that the two phenomena, in mixtures of glycerol with 

 water or the alcohols, are very closely parallel. No minima 

 are found, but every curve shows a falling below the straight 

 line of averages. Hence, we must conclude that glycerol is a 

 solvent resembling water more closely than it does the alcohols, 

 in that mixtures containing it do not have additive properties. 

 This resemblance to water comes out more strikingly when we 

 examine the relative values of the conductivities of the three 

 salts studied here, in the different pure solvents. In water, 

 cobalt chloride, being a ternary electrolyte, has a greater con- 

 ductivity than potassium iodide, and potassium iodide again 

 has a conductivity greater than lithium bromide. The same 

 order is found in glycerol. In ethyl alcohol, and in the tenth- 

 normal solutions in methyl alcohol, the order is potassium iodide, 

 lithium bromide, cobalt chloride. We have already shown that 

 cobalt chloride in ethyl alcohol forms complexes. It is evident 

 that in glycerol the same salt does not form complexes, but 

 behaves like a normal ternary electrolyte in a strongly dissoci- 

 ating solvent. It seems to be broken down, at least partly, 

 into three ions, even in the fairly concentrated solutions in 

 glycerol; and in this point the latter resembles water rather 

 than the alcohols. 



The conductivities of the several electrolytes in pure glycerol 

 do not reach limiting values in the dilutions here worked with, 



but the conductivities for 

 dilutions of four-hun- 

 dredth normal and greater 

 are increasing very 

 slowly; in other words, 

 complete dissociation is 

 probably reached in glyc- 

 erol solutions at a com- 

 paratively small vol- 

 ume. This feature again 

 recalls the dissociating ac- 

 tion of water. 



If we multiply 0.35,' 

 the highest conductivity obtained for potassium iodide in glycerol at 25, by 6.330, 

 the viscosity of the solvent at that temperature, the product is 2.22. Similarly, 

 at 35 the product is 2.10. These numbers, nearly identical, represent lower limits, 

 so to speak, of the product jU M rj for glycerol. It will be recalled that Walden 



25 



75 



Fig. 69. 



50 



Per cent. Glycerol 

 Fluidities of Glycerol Mixtures at 25. 



