142 ON THE DEPRESSION OF THE FREEZING-POINT 



determination of the ionization coefficients of the electrolytes in 

 the mixtures; calculation of the depression of the freezing- 

 point in the mixtures. 



The experiments were carried out during the session of 

 1899-1900 in Dalhousie College, Halifax. 



Materials, Apparatus and Methods. 



The salts and acids were obtained from Merck. The salts 

 were recrystallized once, and it was found that solutions of 

 them, and also of the acid, had conductivity values showing 

 satisfactory agreement with the values as given by l Kohlrausch. 

 These electrolytes were therefore considered sufficiently pure 

 for the purpose. The water used in making the solutions was 

 purified by the method described in my former 2 paper, and it 

 had a conductivity at 18C. of about 0.93 x 10~ 6 expressed in 

 terms of Kohlrausch's new 8 unit (ohm" 1 cm." 1 ). 



The solutions of potassium and sodium chloride were 

 prepared by direct weighing; the salts being first dried to 

 constant weight in an air-bath. The hydrochloric acid solutions 

 were analysed volumetrically by means of a standardized solu- 

 tion of potassium hydroxide with phenol-phthalein as indicator. 

 All burettes and pipettes used in the preparation and analysis 

 of these solutions were calibrated by the weight of distilled 

 water they delivered, and the flasks by the weight of water they 

 held at 0C. 



Observations were made on the specific gravity at 18C. of 

 the simple solutions and their mixtures with a pycnometer of 

 the Ostwald-Sprengel form. These observations were made to 

 obtain the knowledge whether or not there was any change of 

 volume on mixing the simple solutions. It was found that with 

 solutions of the concentrations used, there was no appreciable 

 change, and it was assumed that such would also be the case 

 atO c . 



1 Kohlrausch u. Holborn : Leitvermogen der Elektrolyte, 1898, pp. 159, 160, tab. 2. 



2 Trans. N. S. Inst. Sci., 10, 49, 1898-99. 



3 Kohl. u. Holb., loc. cit., p. 1. 



