118 CONDUCTIVITY AND VISCOSITY 



Subsequently, McMaster found these minima to be more pronounced 

 at lower temperatures, and corroborated the observations of Bingham 

 regarding the relations between conductivity and fluidity minima in 

 these curves. He also noted and offered a tentative explanation of 

 certain maxima in the curves for acetone-alcohol mixtures. 



Although Veazey's work has been fully reviewed in a previous 

 article, it bears directly on the present investigation, since it contains 

 some of the facts earlier established. In addition to confirming the 

 above-mentioned deductions of Bingham, McMaster, and others, 

 Veazey noted and explained the marked increase in viscosity on mixing 

 acetone, as w r ell as the alcohols, with water. This he showed to be due 

 to a mutual diminution in the association of the respective solvents, the 

 resulting mixture having a greater number of ultimate particles and 

 hence a larger viscosity coefficient than either solvent separately. More- 

 over, Veazey was the first to offer an entirely satisfactory explanation 

 of the phenomenon of negative viscosity noted in certain aqueous 

 solutions by a number of previous investigators, and extended this field 

 to include mixed solvents. His interpretation of this phenomenon is 

 now too well known to require more than the mere statement that it is 

 based on the relations of the molecular volume of the solute to that of 

 the solvent, negative viscosity occurring only when the former is much 

 greater than the latter. This relation is, furthermore, borne out by the 

 position of the cations of the solutes causing negative viscosity at the 

 maxima of the atomic volume curve of Lothar Meyer. 



Jones and Schmidt studied glycerol as a solvent, and carried out 

 determinations in both the pure and mixed solvents. They found it 

 well adapted to both conductivity and viscosity wwk, since, in addi- 

 tion to possessing a high viscosity coefficient, it proved to be a good dis- 

 sociant, and showed the largest temperature coefficients of conduc- 

 tivity and viscosity of any solvent hitherto employed. 



Guy and Jones extended greatly the field opened up by Schmidt, and 

 from a large number of measurements pointed out that molecular con- 

 ductivities in glycerol are extremely small, but show a regular increase 

 with dilution and rise in temperature. It was also shown that salts 

 having the greatest hydrating power in water possess the largest tem- 

 perature coefficients of conductivity in glycerol. In mixed solvents 

 Guy and Jones found that conductivities do not follow the law of aver- 

 ages, but are always smaller, and that the ternary electrolytes produce 

 a greater increase in the viscosity of the solvent than the binary elec- 

 trolytes. Isolated instances of negative viscosity were observed both 

 in glycerol and in certain mixtures of glycerol and water, which led 

 Davis and Jones to make a closer study of this phenomenon. 



Davis and Jones, working from the standpoint of negative viscosity, 

 made a careful study of the conduct of rubidium and ammonium salts 

 both in glycerol and in glycerol-water mixtures. They found that 



