216 ON A DIAGRAM OF FREEZING-POINT 
the ratio mentioned really does become constant as dilution 
increases, the method is likely to give coefficients with too low 
or too high values, according as the ratio at moderate dilutions 
diminishes or increases with dilution (it was found to increase 
with KCl and. K,SO,.) For it will probably become constant 
within the limit of error of observation, before it has really reached 
constancy. And if it changes with dilution in a slightly wavy 
manner, even though on the whole tending to constancy, it may 
be regarded as having become constant, when really passing 
through a maximum or a minimum point. 
Déguisne’s* observations on the variation of conductivity 
with temperature between 2°C and 34° have enabled me, by the. 
method just mentioned, to make rough determinations of the 
ionization coefficients at 0° in some cases, on the assumption that 
his empirical constants might be used down to 0°. According to 
Déguisne’s observations, the ratio of the conductivities at 0° and 
18° usually changes gradually down to dilutions of 1,000 litres 
per gramme-equivalent, and between that and 2.000, undergoes 
rapid change. As observations at great dilution are attended by 
considerable difficulty, I have assumed that these sudden changes 
were probably due to errors of observation. If they were not, 
my Déguisne coefticients (for which Déguisne himself is of course 
not. to be held responsible) may be considerably out. 
In some eases, I have obtained coefficients from the above 
data by extrapolation, in order to make use of available depres- 
sion data. In such cases I have plotted, side by side, ionization- 
coefficient-concentration curves, for both 0° and 18°, using values 
for 18° based on Kohlrausch’s conductivities, and I have then 
produced the 0° curve beyond the limit of observation, under the 
guidance of the 18° curve. 
I have used all the accessible observations of depression in the 
case of the electrolytes for which data were available for deter- 
ing the ionization coefficients at 0°, including observations by 
* Temperatur-Coéfticienten des Leitvermégens sehr verdiinnter Losungen, Dis- 
sertation, Strassburg, 1895. See also Kohlrausch u. Holborn: Leitvermégen der Klek— 
trolyte, Leipzig, 1898. 
