132 CONDUCTIVITY AND VISCOSITY 



Jones and Lindsay, 1 continuing the investigation of the phenomenon 

 of minima in conductivity curves observed by Zelinsky and Krapiwin 

 and by Cohen, advanced the theory, based on the hypothesis of Dutoit 

 and Aston, that the decrease in conductivity and fluidity in solvents 

 consisting of mixtures of associated liquids, was due to the fact that 

 each liquid decreased the association of the other, thus decreasing the 

 size of the ultimate unit particles composing the solvent and increasing 

 the amount of frictional surface between them. With these two con- 

 ceptions in mind; i. e., the decrease in association of one associated 

 liquid by another and the subsequent effect of the size of the particles ; 

 it seems clear that by the addition of a third associated liquid to such 

 a binary mixture, the decrease in association would be carried farther, 

 resulting in an increased amount of frictional surface and decreased 

 fluidity. If the unit particles in the acetone were much larger than those 

 already in the binary mixture, the fluidity of the resulting ternary mix- 

 ture would be increased. This is not probable, as acetone is an asso- 

 ciated liquid and the presence of three such liquids, each decreasing 

 the association of the others, would, it is reasonable to conclude, result 

 in a large increase in the number of smaller particles. All conductivity 

 and fluidity measurements taken during this investigation support this 

 view. The comparisons named below furnish some of the evidence for 

 these conclusions. 



To compare the results obtained with those calculated from averages, 

 consider the data obtained by Davis and Jones with glycerol-water 

 mixtures and by Davis, Hughes, and Jones with acetone-water mix- 

 tures. They used rubidium bromide in the following solvents: 75 

 p. ct. glycerol and 25 p. ct. water (A) ; 75 p. ct. acetone and 25 p. ct. 

 water (B) ; 50 p. ct. glycerol and 50 p. ct. water (C) ; 50 p. ct. acetone 

 and 50 p. ct. water (D). 



It should be noted that the action of all four salts used in this inves- 

 tigation do not differ widely in the same solvents. The average 

 obtained with the 2-1-1 and 1-2-1 solvents can be compared with the 

 A and B solvents, since all contain 25 per cent water. The 75 per cent of 

 ternary mixture is, by averaging the 1-2-1 and 2-1-1 solvents, equally 

 divided between glycerol and acetone. Solvents C and D can be com- 

 pared with the 1-1-2 solvents, since all contain 50 per cent water. 



The fluidity of the 1-1-1 solvent is about one-sixth that calculated 

 from averages; while the specific conductivity is, as noted above, about 

 3,000 times that calculated by the same method; hence the specific 

 conductivity of the solvent is 18,000 times that which would be 

 expected. While these figures can be considered only as a very rough 

 approximation, they indicate a relatively large dissociation in these 

 ternary mixtures. 



'Carnegie Inst. Wash. Pub. No. 80. 



