BY MIXTURES OF ELECTROLYTES—BARNES. 141 
of molecules and ions present seems to affect the power which 
one molecule or ion has of lowering the freezing-point, it was 
assumed that the depression produced by a molecule or an 
ion of say, the electrolyte 1, which is surrounded by mole- 
cules and ions of this electrolyte 1 and of the other electro- 
lytes 2, 3, ete., would have the same value as if all the molecules 
and ions surrounding it were of electrolyte 1. ‘Thus the M’s 
of the above expression have been regarded as equal to the 
molecular depressions in simple solutions of the concentration 
N,+N,+ ete. 
The application of this expression to the calculation of the 
depression in mixtures will form at once a test of the above 
assumption and a test of the ionization coefficients employed. 
I have applied it (a) to mixtures of potassium chloride and 
sodium chloride, these salts being selected because of their 
simple molecular structure and the approximate equality in their 
gerade of ionization; (b) to mixtures of sodium chloride and 
hydrochloric acid, selected because of their simple molecular 
structure and the considerable difference in their grade of 
ionization; (c) to mixtures of potassium chloride, sodium 
chloride and hydrochloric acid, selected for testing in addition 
the method of finding the ionization coefficients in a mixture of 
three electrolytes. 
The following is a synopsis of the work involved :—Purifica- 
tion of materials ;—construction and calibration of the instru- 
ments used in the conductivity and freezing-point observations ; 
—preparation and analysis of a series of simple solutions of the 
three electrolytes ;—determination of the specitic molecular 
conductivities at infinite dilution for 0°C. ;—observations on the 
conductivity at 0° for the series of simple solutions ;—calcula- 
tion of the ionization coefficients at 0° from the conductivity 
observations ;—measurement of the depression of the freezing- 
point of the simple solutions ;—calculation of the molecular 
depression for each solution of the three electrolytes ;—prepara- 
tion of mixtures of two and of the three electrolytes ;—measure- 
ment of the depression of the freezing-point of the mixtures ;— 
