II].— On THE DEPRESSION OF THE FREEZING-POINT BY 
MixTURES OF ELECTROLYTES.—BY JAMES BARNES, B. A., 
Dalhousie College, Hulifax, N. 8. 
(Communicated by Professor J. G. MacGregor on March 12th, 1900.) 
In a ‘paper communicated last winter to this Society, Mr. 
KE. H. Archibald described experiments he had made to test the 
ionization coefficients, obtained by *? Prof. MacGregor’s method, 
for mixtures of equimolecular solutions of two electrolytes 
having an ion in common. With these coefficients and Van’t 
Hoff’s constant as data, he calculated the depression of the 
freezing-point of the mixtures; and he then compared the 
calculated with the experimental values. It was found that the 
difference between these values was, in general, equal to the 
arithmetic mean of the differences between the calculated and 
experimental values of the depressions of the constituent simple 
solutions, and the test was therefore concluded to be satis- 
factory. 
At Prof. MacGregor’s suggestion, I undertook similar 
experiments with mixtures, not of equimolecular solutions, 
but of solutions of different concentrations. The electrolytes 
selected were potassium chloride, sodium chloride, and hydro- 
chloric acid. 
In the case of mixtures of solutions which are not equi- 
molecular Mr. Archibald’s method of testing the ionization 
coefficients is not applicable. I found it necessary, therefore, to 
obtain an expression for the depression of the freezing-point for 
such mixtures in terms of the ionization coefficients. 
In a simple solution containing 7 gramme-molecules of an 
electrolyte per litre, if @ is the ionization coefficient, the 
number of dissociated molecules is 7 a and the number of undis- 
sociated (L—a@) n. Ifa molecule of this electrolyte breaks down 
1 Trans. N.S. Inst. Sci., 10, 33, 1898-99. 
2 Thid., 9, 101, 1895-96. 
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