Conductivities and Viscosities in Formamid and in Mixed Solvents. 93 



little or no solvating power. This may be accounted for upon the basis 

 of a decrease in the complexity of the solvate with rise in temperature, 

 giving greater mobility to the ions. 



The viscosities of the solutions of these nitrates in formamid increase 

 in numerical value as we pass from the alkalis to the alkaline earths 

 i. e., the effect of the anion being the same, the viscosity varies with the 

 size of the cation, the increase in viscosity being less in the case of the 

 salts of ca?sium, rubidium, and ammonium and becoming greater as we 

 pass through those of potassium and sodium to calcium, barium, and 

 strontium. There are two ways of viewing this phenomenon. From 

 the standpoint of the theory of Jones and Veazey, the smaller increment 

 in the viscosity of the solvent caused by the salts of the first three 

 alkali metals is due to their large atomic volume, which produces a 

 decrease in the total fractional surfaces of the particles in a given 

 volume of the solution. On the other hand, it has been shown that 

 substances with the largest molecules give the greatest increase in the 

 viscosity of the medium and that by increasing the complexity of the 

 solvent the viscosity of the solution becomes greater. From this 

 standpoint it would appear that the small increment in the viscosity of 

 formamid caused by salts of csesium, rubidium, and ammonium is due 

 to the slight solvation of their cations, while the greater value obtained 

 for the other alkalis and for the salts of the alkaline earths is due to the 

 increase in the complexity of the solute due to solvation, the resulting 

 complex being larger than the non-solvated ions of the alkali metals. 

 Previous work in this laboratory has supported the view of Jones and 

 Veazey, but the work in mixed solvents containing formamid to be dis- 

 cussed later seems to favor the latter hypothesis. 



TABLE 54. Comparison of Conductivity and Dissociation of Formates in 

 Formamid and in Water at 25 C. 



'Carnegie Inst. Wash. Pub. Nos. 170 and 230. 



A glance at table 54 will show that these salts of a strong organic 

 acid exhibit similar characteristics in formamid to the nitrates i. e., 

 they are more strongly dissociated at low dilutions than in water, 

 although the actual conductance is much less. The temperature 



