SECTION III., 1900. [8] Trans. R. S. C. 
I.—On the Depression of the Freezing-Point in Aqueous Solutions 
of Electrolytes. 
By Pror, J. G. MacGrea@or, Dalhousie College, Halifax, N.S. 
(Read May 29th, 1900.) 
In a paper communicated to the Nova Scotian Institute! of Science, 
some time ago, I showed that the values of certain physical properties of 
dilute aqueous solutions of electrolytes might be expressed, within the 
limits of error of their measurement, by means of a simple function of 
their concentration and ionization, and that many of the laws which such 
properties have been found to follow, might thus be co-ordinated and 
accounted for. In subsequent papers by my students’ additional evi- 
dence in support of this position has been supplied. 
If P and P, represent the values of the property for the solution 
and for water respectively, n the concentration, @ the ionization co- 
efficient and k and / constants (referred to below as ionization con- 
stants) for the property in question and for a given electrolyte at a 
given temperature, the function mentioned had the form: 
P=P,+k(l—a)n+lan. 
If the concentration is expressed in terms of the gramme-equivalent 
per litre, k is the contribution made by each gramme-equivalent of the 
undissociated electrolyte to the excess in the value of the property for 
the solution over its value for water, and / that due to each gramme- 
equivalent of the dissociated portion. The expression embodies the 
assumption that at sufficient dilution, when the molecules are at such 
distances from one another that their mutual action is negligible, the 
excess in the value of the property for the solution over the value for 
water will be additively compounded of the contributions made by the 
undissociated molecules and the free ions. 
In the papers referred to above, the properties discussed were 
specific gravity, surface tension, thermal expansion, viscosity and re- 
fractive index. In the present paper I wish to show that the same 
expression is applicable to the freezing-point, and that this knowledge 
may be used in obtaining approximate values of the amounts of 
depression produced in the freezing-point, per gramme-molecule by the 
undissociated molecules, and per gramme-ion by the free ions. 

1 Trans. N.S. Inst. Sci., 9, 219, 1896-7; and Phil. Mag. (5), 43, 46 and 99, 1897. 
2 Archibald: Trans. N.S. Inst. Sci., 9, 335, 1897-8; Barnes: Zbid. 10, 49 and 113, 
1898-1900. 
