1904.] Experimented Determinations for Saturated Solutions. 435 



" Experimental Determinations for Saturated Solutions." By the 

 Earl of Berkeley. Communicated by F. H. Neville, F.K.S. 

 Eeceived March 28 — Eead May 19, 1904. 



(Abstract.) 



The object of this research is the experimental determination of 

 those physical constants of concentrated solutions, which are necessary 

 for the tentative application of the gas-law equations. Saturated 

 solutions were chosen because, presumably, dissociation is relatively 

 at a minimum. 



This part of the work deals with the densities and solubilities of 

 the chlorides, sulphates, and nitrates of sodium, potassium, rubidium, 

 caesium, . and thallium, and also with their respective alums, except 

 that of sodium. 



The densities were determined by means of a small pipette- shaped 

 pyknometer, of about 5 c.c. capacity, the lower end of which was 

 turned upwards and the upper, 120 mm. long, was graduated. This 

 was filled with the saturated solution and weighed, and from the 

 known capacity of the pyknometer, together with the weight of solu- 

 tion it contained, the density was calculated. The solubility was 

 obtained by washing out the contents of the pyknometer and evapo- 

 rating to dryness,, the weight of salt left giving the solubility. 



The densities and solubilities Were determined in two ways. In 

 one the saturated solution, which was in contact with an excess of 

 salt and continuously stirred, was cooled to the temperature of 

 observation and the density and solubility determined. In the other 

 an unsaturated solution was raised to the temperature of observation, 

 being continuously stirred in contact with an excess of salt (in both 

 cases the solution is kept at the temperature of observation by means 

 of a thermostat), and the density determined at intervals of about 

 12 hours until constant. 



This constant density and resulting solubility was averaged with 

 the density and solubility obtained in the first method, and the mean 

 was assumed to be the true density and solubility of the saturated 

 solution. The observations were made at intervals of 15°, in this 

 manner, between 0° C. and 90° C. 



The constants were also determined at the boiling point of the 

 saturated solutions in an apparatus in which steam was caused to 

 bubble vigorously through the solution with excess of salt, until the 

 temperature became constant, this constant temperature being assumed 

 to be the boiling point. 



The boiling point itself was not accurately determined, as it was 



