176 WORK OF J. SAM GUY. 



Potassium chloride and sodium nitrate are nearly insoluble in the alcohols, and 

 yet curves expressing the conductivities of these salts in mixtures of the alcohols with 

 glycerol are strikingly similar to those of ammonium bromide. This seems to indi- 

 cate that the deviation from the law of averages is due largely to the change in 

 association of the glycerol. 



Table 118 gives a comparison of the percentage temperature coefficients of con- 

 ductivity from 25 to 35 of all the salts we have studied in mixed solvents. In pure 

 glycerol these values are very large, from 10 to 11 per cent per degree rise in temper- 

 ature. They decrease very rapidly with the addition of either water or the alcohols. 

 The temperature coefficients also decrease very rapidly with rise in temperature. 



VISCOSITIES AND FLUIDITIES. 



Table 119 includes the viscosities and fluidities of the eighteen electrolytes whose 

 conductivities we have studied. Measurements were made only with the tenth- 

 normal solutions, since, at higher dilutions, the difference in viscosity between the 

 solution and solvent is hardly large enough to be detected, much less measured. In 

 nearly every case the viscosity of the solution is greater than that of the solvent. 

 Ammonium bromide was found to be an exception to this rule, and will be discussed 

 more fully. The temperature coefficients of fluidity are very large, being somewhat 

 greater than the temperature coefficients of conductivitj^. That the former are 

 larger than the latter is not surprising, since rise in temperature would decrease the 

 dissociation and thus decrease the conductivity, which would, at least in part, offset 

 the increase in conductivity caused by increase in fluidity. 



The ternary electrolytes show a much greater increase in viscosity than the binary 

 electrolytes. It will be recalled that the salts which show the greatest increase in 

 viscosity are those in which the solvation seemed to be the greatest. 



This increase in viscosity of the ternary over the binary electrolytes may be due 

 to several causes. There may be a greater number of ions present, which, since the 

 viscosity is a function of the skin friction, would increase the viscosity; or the mole- 

 cules of the solvent, combined as solvates, may be so attached to the molecule of the 

 solute as to hinder its movement. It is not supposed that in any case of solvation the 

 molecules of the solvent are held so as to form a complex chemical molecule, as this 

 would, of course, decrease skin friction and thus lessen the viscosity of the solution. 



The fact that solutions of ternary electrolytes show greater viscosities than solu- 

 tions of binary electrolytes may be a conditioning factor in the small molecular con- 

 ductivity shown by them in the more concentrated solutions. It is, however, hardly 

 possible that this could account entirety for the phenomenon, since there is probably 

 less actual dissociation of a ternary than of a binary electrolyte in the most con- 

 centrated solutions. 



It is probable, then, that the large viscosity of the ternary electrolytes in glycerol 

 is due to a summation of at least two effects; the small atomic volumes of barium, 

 strontium, calcium, and cobalt, and possibly to some factor caused by solvation of 

 the ions or molecules of the electrolytes, which, as stated above, would probably be 

 greater with the salts of these metals than with salts of sodium, potassium, and 

 ammonium. 



