OF CERTAIN SALTS IN TERNARY MIXTURES. 119 



rubidium salts produced a phenomenal lowering of the viscosity of 

 glycerol, while ammonium salts proved to be more closely allied to 

 rubidium than to potassium in their effects on a solvent like glycerol. 

 They also noted minima in certain of the conductivity curves for the 

 more concentrated solutions studied; the conductivity varying directly 

 with the fluidity. In addition to this the percentage increase in fluidity 

 was found to diminish rapidly with rise in temperature and with dilu- 

 tion, and the curves representing fluidity and conductivity in glycerol- 

 water mixtures showed marked similarity. No evidence of positive 

 viscosity of solutions of rubidium salts in glycerol was found, and in 

 the case of mixed solvents only at comparatively high temperatures. 



The study of the behavior of rubidium salts in mixed solvents was 

 extended by Davis, Hughes, and Jones to acetone-water mixtures. A 

 marked increase in viscosity was found for all the rubidium salts in the 

 solvents containing the larger percentage of acetone, a phenomenon 

 which this electrolyte had exhibited in none of the solvents previously 

 studied. The curve representing the fluidity of solutions of these salts 

 in the different mixtures was observed to cross that of the solvents in 

 the vicinity of the mixture containing 50 per cent acetone. Negative 

 viscosity coefficients, wherever noted, were much smaller than corre- 

 sponding values in glycerol-water mixtures. A comparison of the tem- 

 perature coefficients of fluidity and conductivity showed them to be 

 very similar, and of the order of magnitude to be expected for a non- 

 solvated salt in a mixture of associated solvents. In addition, minima 

 were noted in the conductivity curves for these salts, and were found to 

 correspond to a higher percentage of acetone in the solvent than in the 

 case of similar minima in the fluidity curves. 



The important observations on solutions in binary mixtures made by 

 the above-mentioned investigators in this laboratory make it evident 

 that some lines of evidence are desirable, on the behavior of certain 

 salts in ternary mixtures containing the three important solvents dis- 

 cussed, viz, glycerol, acetone, and water. The present investigation, 

 therefore, has been devoted to a study of the behavior of rubidium and 

 ammonium salts which exhibit negative viscosity to a high degree in 

 many pure solvents and their binary mixtures, in a new series of sol- 

 vents which contain varying proportions of glycerol, acetone, and water. 



EXPERIMENTAL. 

 APPARATUS. 



Thermostats. As in previous years, it has been our constant aim to 

 bring to as near perfection as possible this fundamental part of the 

 apparatus. With this in view, a new type of thermostat (fig. 52 A) 

 has been devised suitable both for conductivity and viscosity determi- 

 nations, or for reaction velocity work; and three such baths have been 

 recently installed and put into full working order (Plate I). These 

 thermostats are of about 60 liters capacity and are substantially con- 



