10 Conductivities and Viscosities in Pure and in Mixed Solvents. 



broken up with rise in temperature. Since these salts are the least 

 solvated, the first assumption is apparently the more plausible. 



Meaurements are now in progress of the effect of these salts on the 

 viscosity of glycerol and of glycerol-water mixtures. 



THE VISCOSITIES OF BINARY MIXTURES OF THE ASSOCIATED 

 LIQUIDS, WATER, FORMIC ACID, AND ACETIC ACID. 



Jones and Murray 1 showed in 1903 that when two associated liquids 

 are mixed each diminishes the association of the other. They deter- 

 mined the molecular weight of water in formic acid on the one hand 

 and in acetic acid on the other. Also the molecular weight of formic 

 acid in water, and in acetic acid, and finally the molecular weight of 

 acetic acid in water and in formic acid. 



They found that the molecular weight of water in formic acid varied 

 from 19.7 at dilution 0.93 N to 21.9 at 6.18 N, showing that the formic 

 acid diminished slightly the association of the water. 



The molecular weight of water in acetic acid varied from 21.7 at 0.64 

 N to 38.8 at 12.65 N. This showed that the acetic acid diminished 

 greatly the association of the water. 



The molecular weight of acetic acid in water varied from 55.4 at 0.17 

 N to 72.1 at 7.06 N, showing that water diminished very appreciably 

 the association of acetic acid. 



The molecular weight of acetic acid in formic acid varied from 61.9 

 at 0.18 N to 83.8 at 9.17 N. The association of the acetic acid was thus 

 diminished considerably by the formic acid. 



The molecular weight of formic acid in water varied from 45.2 at 0.38 

 N to 51.0 at 6.16 N, showing that water had very little effect on the 

 association of the formic acid; and, finally, the molecular weight of 

 formic acid in acetic acid varied from 50.4 at 0.82 N to 65.7 at 8.26 N. 



If we take into account the dissociating action of the water on 

 formic and acetic acids, we are justified in concluding that water and 

 formic acid affect each other's association very little; acetic acid and 

 formic acid affect each other's association considerably, while both 

 water and acetic acid have a marked effect each on the association 

 of the other. These facts were used by Jones and Veazey 2 to explain the 

 increase in viscosity which takes place when water and alcohol are mixed. 

 These are both strongly associated solvents, and each, therefore, very 

 probably diminishes appreciably the association of the other. From 

 a smaller number of larger molecules of each solvent, we have a larger 

 number of smaller molecules of each solvent produced. The surfaces 

 of the molecules present are therefore increased, and, consequently, 

 the friction of these molecules as they move over one another. Vis- 

 cosity is a function of the surface friction of the molecules. 



'Amer. Chem. Journ., 30, 193 (1903). 



'Zeit. phys. Chem., 61, 641; 62, 44 (1908); Carnegie Inst, Wash. Pub. No. 80, 170 (1907). 



