VOLUME CHANGES IN THE PROCESS OF SOLUTION. 75 



of a solute varies slightly in different solvents, the order of 

 variation in most cases being the same as that of the com- 

 pressibility of the solvent. In cases where the process of 

 solution is accompanied by no change in the molecular 

 complexity of both solute and solvent the specific solution 

 volume is found to be practically independent of concen- 

 tration. In aqueous or alcoholic solutions, however, it has 

 been repeatedly shown that the specific volume of the 

 solute varies with its concentration. The results recorded 

 in the present paper were obtained chiefly from experi- 

 ments with solutions in water or alcohol, or in mixtures 

 of these solvents. All the reagents used in this investiga- 

 tion were purified by suitable means, and their final purity 

 determined by physical methods, e.g., density, melting point 

 or boiling point. The solutions were all prepared by weigh- 

 ing both solute and solvent. The density of the solvent or 

 solution was determined by means of a pyknometer of 

 capacity about 22 cc. Before adjusting the volume of the 

 liquid in the pyknometer it was allowed to remain suspended 

 for about an hour in a thermostat, the temperature of 

 which was maintained constant to 0*05° 0. All weighings 

 were reduced to vacuo. 



Aqueous Solutions. 

 In the following tables, A represents the concentration 

 of solute in grams per 100 grams of solvent, do the density 

 of the pure solvent, di the density of the solution, v s the 

 specific solution volume of the solute (Equation I), and <£ 

 the molecular solution volume of the solute (Equation II). 

 The temperature is stated in each case. 



Table I. 



Potassium chloride in water (d = -997073). Temp. 25° C. 

 A di : v* <f> 



•1637 -998117 -361 2G-92 



•4221 -999775 -358 20-71 



