212 GENERAL DISCUSSION OF RESULTS. 



It was further observed that salts of calcium, strontium, and barium have larger 

 temperature coefficients of conductivity than those of sodium, potassium, and am- 

 monium. The former are very strongly hydrated, while the latter are only slightly 

 hydrated. It is not at all surprising to find that the former combine with far more 

 glycerol than the latter. It should also be noted that salts which have approximately 

 the same hydrating power show temperature coefficients of conductivity in glycerol 

 of the same order of magnitude. The same facts that came out between 25 per cent 

 and 45 per cent manifest themselves also over the higher temperature range, 55 

 to 75. The conductivities in the mixed solvents do not follow the law of averages, 

 but are always less, as is shown by the deviation of the curves from a straight line. 

 This has been explained by the work of Jones and Lindsay and of Jones and Mur- 

 ray. 1 Each solvent diminishes the association of the other. 



An interesting observation was made in the case of sodium nitrate and potassium 

 chloride. These salts are only slightly soluble in alcohol, and yet their conduc- 

 tivities in mixtures of alcohol and glycerol are strikingly analogous to those of a salt 

 like ammonium bromide, which is soluble in both solvents. This would indicate 

 that the deviation from this law of averages in these cases was due primarily to a 

 change in the association of the glycerol. Study was made of the viscosities of 

 tenth-normal solutions of all of the salts whose conductivities were measured. In 

 most cases the viscosity of the solution was greater than that of the solvent, ammo- 

 nium bromide being an exception. The temperature coefficients of fluidity are 

 somewhat larger than those of conductivity. This would be expected, since rise in 

 temperature diminishes the dissociation. This would diminish the conductivity 

 and partly affect the increase in conductivity due to increase in fluidity. 



Solutions of ternary electrolytes have much greater viscosity than solutions of 

 binary. Those salts whose solutions have the greatest viscosity are the most sol- 

 vated or combine with the largest amounts of the solvent. This may be due to the 

 fact that ternary electrolytes yield more ions in solution than binary, and there being 

 more surface to the ions than to the molecule from which they came, the surface, and 

 consequently the surface friction, would be thus increased. Viscosity is an expres- 

 sion of the surface friction. Probably the small atomic volumes of calcium, stron- 

 tium, barium, and cobalt also have something to do with the large viscosities of 

 solutions of their salts in glycerol. 



It may be said, in general, that the curves representing the change in conductivity 

 of salts in glycerol with temperature and those representing the change in fluidity 

 are very similar, conductivity and fluidity running almost parallel from 25 to 75. 



Analogous relations were found to hold in the mixed solvents, the viscosity of the 

 solution being nearly always greater than that of the pure mixed solvent. 



The viscosity of glycerol changes very rapidly with temperature. It is obvious 

 that there is a close connection between the viscosity of a solvent and the velocity 

 of the reaction in that solvent. The ions must first come near together before they 

 can react chemically. The frequency of their approach is conditioned by the vis- 

 cosity of the solvent. We propose to study reaction velocities in glycerol from the 

 standpoint of the relation between reaction velocities and viscosity, and the change 



Carnegie Institution of Washington Publication Xo. 80. 



