Viscosities of C cesium Salts. 



11 



In the same manner Jones and Veazey were able to explain why it 

 is that salts of potassium, rubidium, and caesium lower the viscosity 

 of water and other solvents 1 in which they are dissolved. The large 

 atomic volumes of these cations, when mixed with the molecules of 

 water, diminish the frictional surfaces which come in contact, and, 

 consequently, diminish the viscosity. 



Having found the above action of water, formic acid, and acetic acid, 

 each on the association of the other, the question arose, What would be 

 the effect of each on the viscosity of the other? If the above explana- 

 tions offered by Jones and Veazey were correct, then two liquids, like 

 water and acetic acid, which diminished each other's association, ought 

 to increase the viscosity of one another the viscosity of the mixture 

 should be greater than that of either pure liquid separately. 



The viscosities of binary mixtures of the above-named three liquids 

 were measured at 15 and 25. Water was regarded as the solvent for 

 formic acid and acetic acid, and solutions of these acids in water were 

 prepared containing by volume 10, 20, 30, 40, 50, 60, 70, 80 and 90 per 

 cent. The acids themselves contained somewhat less than 1 per cent 

 of water. The viscosity and the fluidity (reciprocal of viscosity) data 

 are given in tables 2 to 4. 



TABLE 2. Viscosities and Fluidities of Formic Acid in Water at 15 and 25. 



The viscosity data at 15 are plotted in curves, fig. 1, and the vis- 

 cosity data at 25 in curves, fig. 2. The viscosities of acetic acid in 

 water pass through a well-defined maximum, which, before we carried 

 out a single measurement of the viscosities of mixtures of these two 

 solvents, 2 we predicted would be the case from the molecular-weight 

 determinations of this acid in water made by Jones and Murray. 



The viscosities of formic acid in acetic acid pass through a slight 

 maximum, as would be expected from the effect of each of these sol- 

 vents on the molecular weight of the other. 



Uones and Davis: Zeit. phys. Chem., 81, 68 (1912) ; Cam. Inst. Wash. Pub. No. 180, 179 (1913). 



*Since completing our work we find that a few measurements of the viscosities of mixtures of 

 acetic acid in water had been made by Dunstan and Thole: Journ. Chem. Soc., 85, 825 (1904); 

 95, 1560 (1909). 



