194 



WORK OF P. B. DAVIS. 



change in temperature would produce the greatest effect where the solvation was 

 greatest, viz, in the more dilute solutions, and in solutions of those salts which have 

 the greatest power of solvation. 



The per cent temperature coefficients are seen to be very large, being from 10 to 

 11 per cent between 25 and 35. They decrease rapidly with rise in temperature, 

 the values between 65 and 75 lying between 4.5 and 5 per cent. This may be 

 partially accounted for b} r the enormous decrease in the viscosity of glycerol with 

 rise in temperature. At 25 glycerol has a viscosity approximately 660 times that 

 of water, while at 35 the value is 370 times that of water but little more than half 

 as great. At 75 the ratio falls to 70. In no other common solvent 

 are the temperature coefficients of conductivity so great, and the 

 above ratios will show to some extent why this should be the case. 



Tables 131 to 138, inclusive, contain the molecular conductivities 

 at 25, 35, and 45 of ammonium iodide and rubidium bromide in 

 mixtures of glycerol with water. Figs. 81 and 82 express these results 

 graphically. The solvents were 



prepared by diluting n c.c. of 

 glycerol to 1 liter and denoting 

 the resulting solvent as a mixture 

 of n per cent glycerol with water. 

 It will be seen that the conduc- 

 tivity curves of such mixtures 

 show a decided sagging, the con- 

 ductivity values being always 

 less than would be expected from 

 the law of averages. The expla- 

 nation of this has been given by 

 Jones and Lindsay 1 and by Jones 

 and Murray 2 for mixtures of 

 water with the alcohols, and has 

 been extended to mixtures con- 

 taining glycerol by Guy and 

 Jones. When two highly asso- 

 ciated liquids are mixed, or, to 

 take a specific instance, when 

 glycerol is mixed with water, it 

 has been shown that in such a 



I, - V=io 

 II, - V=50 



III, V=400 



IV, - V=1600 



100 



150 

 III 



o 



3 

 -O 



c 

 o 



'a 



"3 



j> 

 5 



S 



-50 



Fig, 



Per cent. Glycerol 



81. Conductivity of Ammonium Iodide in 

 Glycerol-VVater at 25. 



case the properties of the mixture are not additive, each solvent tending to break 

 down the association of the other; the combined dissociating effect of the two being 

 less than would be expected had there been no such mutual diminution of the asso- 

 ciation. Guy and Jones have shown that in the case of glycerol mixtures with the 

 alcohols the diminution of the association takes place largely in the case of the 

 glycerol. 



In table 139 a comparison is made of the temperature coefficients at 25 to 35 of 



'Amer. Chem. Journ., 28, 329 (1902). 



*Ibid., 30, 193 (1903). 



