GENERAL DISCUSSION OF RESULTS. 211 



It was found that fi^ for glycerol, multiplied by 77, the viscosity, gave the value 

 2.22 at 25 and 2.10 at 35. Walden found a constant value of this product for 

 about 30 organic solvents; but water, having the value 1.0, and glycol the value 1.32, 

 were exceptions; glycerol is another exception. This may be due to the presence 

 of the three hydroxyl groups, since water with one and glycol with two hydroxyls 

 are also exceptions, and glycerol is the most pronounced exception of the three. 



RESULTS OBTAINED BY GUY. 



The conclusions reached as the result of the investigation by Schmidt were based 

 upon the study of a very few compounds, and these were investigated at only a few 

 temperatures. This earlier work showed, however, that glycerol is such an inter- 

 esting and important solvent that it seemed desirable to study solutions of a much 

 larger number of salts in it, and to study these over a much larger range in tempera- 

 ture. The work of Dr. Guy was undertaken for this purpose. The temperature 

 range in this work was 25 to 75, and the salts investigated were potassium nitrate, 

 potassium chloride, potassium bromide; sodium chloride, bromide, iodide, and nitrate; 

 ammonium chloride, bromide, and nitrate; barium chloride, bromide, and nitrate; 

 calcium bromide, strontium bromide and nitrate, and cobalt chloride and bromide. 



Potassium chloride, sodium nitrate, ammonium bromide, and strontium chloride 

 were studied also in mixtures of glycerol with water and the alcohols. 



The viscosities and fluidities of solutions of all of the above-named salts in glycerol 

 were determined at 25, 35, and 45, and of a number of them at 55, G5, and 75. 



The viscosities and fluidities of solutions of a number of these salts were deter- 

 mined in mixtures of glycerol and water, glycerol and ethyl alcohol, and glycerol and 

 methyl alcohol. 



In no other solvents is there such a marked change in conductivity with change 

 in temperature, as in glycerol. This change in conductivity with rise in temperature 

 may be due to either of the following causes: A change in the dissociation with rise 

 in temperature, or a change in the velocities of the ions as the temperature is varied. 

 That the temperature coefficients of dissociation, over the above range in tempera- 

 ture, is small is shown by abundant evidence. The main factor, therefore, increasing 

 the conductivity with rise in temperature, is an increase in the velocity of the ions. 

 This may be due to a diminution in the viscosity of the solvent with rise in tempera- 

 ture, or to a breaking down of complex solvates around the ions. We know that the 

 viscosity decreases rapidly with rise in temperature, but we also have evidence that 

 there is solvation in glycerol as a solvent, or the formation of glycerolates by the 

 dissolved substances. 



The temperature coefficients of conductivity in glycerol are greater at high than 

 at low dilution. Jones 1 has pointed out that this would be expected from the solvate 

 theory for aqueous solutions, and the same conclusion holds for glycerol as a solvent. 

 The more dilute the solution the more complex the solvate; the more complex 

 the solvate the greater the change in the complexity with rise in temperature. This 

 fact would indicate that glycerolates exist in solutions in glycerol as the solvent. 



'Carnegie Institution of Washington Publication No. 80. 



