WORK OF P. B. DAVIS. 

 Table 144. Percentage Increase in Fluidity of Glycerol-Water Mixtures at 25. 



L93 



DISCUSSION OF RESULTS. 



The hypothesis of Dutoit and Aston, already referred to, makes the dissociating 

 power of a solvent a function of its own association. The degree of association of a 

 solvent by the method of Ramsay and Shields has been shown to decrease with rise 

 in temperature. Therefore the increase in conductivity usually observed with rise 

 in temperature can not be due to an increase in the number of ions present, but must 

 be caused by an increase in the velocity of those ions. As Guy and Jones have 

 already brought out, the change in the velocity of the ions with rise in temperature is 

 to be ascribed to the change in the viscosity of the media surrounding the ions, and 

 in some instances to the change in the mass of the ionic complexes formed by the ions 

 and a certain number of molecules of the solvent. 



Previous workers with glycerol as a solvent have already noted the enormous 

 increase in the conductivity of solutions in it with rise in temperature. While Guy 

 and Jones have found some evidence for the existence of glycerolates, we believe 

 the chief conditioning factor to be the change in the viscosity of the solvent. It is 

 with the viscosity phenomena, and chiefly with the lowering of the viscosity of 

 glycerol by certain salts, that this investigation has had to deal. 



Both conductivity and viscosity data have been obtained for the various salts and 

 are given in tabular form with accompanying tables of temperature coefficients. 



Tables 126 to 130, inclusive, contain the molecular conductivities at ten-degree 

 intervals from 25 to 75 of ammonium iodide and of the several rubidium salts 

 which have been studied in pure glycerol as a solvent. In agreement with the work 

 of preceding investigators, viz, Jones and Schmidt, and Guy and Jones, all the values 

 for iJL t are seen to be extremely low much smaller than the corresponding values in 

 water. These values show a marked increase with rise in temperature, and in the 

 more dilute solutions (N/10 to N/1600) a regular increase with dilution. It is to be 

 noted that in the more concentrated solutions, especially of the iodides, a decrease in 

 conductivity takes place, the minimum lying as a rule close to the value for the N/10 

 solution. A discussion of this phenomenon will be taken up after a review of the 

 viscosity data. 



The corresponding temperature coefficients of all the salts studied, both in con- 

 ductivity units and in percentages, are of the same order of magnitude and show the 

 same relative increase with increased dilution. This is to be expected, since these 

 salts are all binary electrolytes, and since all belong to that class whose cations, pos- 

 sessing the largest atomic volumes, have been shown to have little or no hydrating 

 power in water. Such is not the case with ternary electrolytes in glycerol and espe- 

 cially with salts of calcium, strontium, barium, and cobalt, the explanation of which 

 has been fully given by Guy and Jones, who base their conclusions on the solvate 

 theory. They point out that if there is solvation this should be more marked in the 

 more dilute solutions where the amount of solvent per ion is greatest. Hence a 



