[BARNEs] DEPRESSION OF THE FREEZING-POINT 49 
According to Van’t Hoffs theory the value of the molecular depression 
should be about 1:86. Loomis! found experimentally with a large num- 
ber of non-electrolytes that this depression was 1°86 for dilute solutions and 
generally increased in value asthe solutions became more concentrated. I 
have in a former paper” shown that, with the electrolytes KCl, NaCl, 
and HCl, the molecular depressions are also grouped around this value. 
It is seen in the above Table IV that for HC/ the molecular depression 
is about 1:84 in the dilute solutions and increases to 1-91 in the stronger. 
This divergence may partly be accounted for by the employment of the 
quotients of the specific molecular conductivity by the specific molecular 
conductivity at intinite dilution (4/44) as the values of the ionization 
coefficients (a), because the more concentrated the solution the greater 
will u/ux differ from a. The molecular depression 1:84 in the weak 
solutions instead of 1°86 may be caused by the value of the specific 
molecular conductivity at infinite dilution at 0° being not correct. Even 
its value at 18° is very doubtful, especially so in the case of acids. Its 
magnitude is thought to be too small rather than too great. If it is too 
small then the ionization coefficients obtained therewith are too large and 
therefore the molecular depressions, as calculated above, are too small. In 
the case of the H,SO, as above, the molecular depressions calculated on 
the assumption that H,SO, dissociates into H, H, and SO, in these 
solutions of moderate dilution are in nearly as good agreement with the 
theoretical value as those values are which are calculated by the same 
equation when there is no doubt as to the mode of ionization. On the other 
hand if we suppose H,SO, to dissociate into H and HSO, we obtain 
results as in the table which are thirty per cent greater than the value 
the theory requires. 
It will be of interest to show how the above depressions of the 
freezing-point compare with the results of Loomis’ and Jones.f As the 
best view of the results can be obtained when they are graphically ex- 
pressed the following Figure 2 has been introduced. Before my results 
could be compared with those of the above observers it was necessary 
to reduce the concentrations which are expressed in gramme-molecules 
per litre at 0° to the same at 18°. This was carried out by means of 
Marignac’s° data on the thermal expansion of solutions of these acids. 
For clearness in the figure the values of the depression of the freezing- 
point (6) divided by the concentration (n), t.e., the quotients d/n have 
been plotted as abscisse against the concentrations (x) as ordinates, and 

1 Phys. Review, 9, 257, 1899. 
2Trans. N.S. Inst. Sci., 10, 153, 1900. 
3 Phys. Review, 3, 276, 1896 and 1, 281, 1894. 
4 Phil. Mag. (5), 36, 474, 1893. 
> Ann. Chim. Phys. (4), 22, 385, 1871. 
