SOLUTIONS.—MACGREGOR. ba 
It will thus be seen that Schrader’s coefficients differ from 
mine by various amounts up to about 10 per cent., being in 
most cases smaller, but in some greater. It should be noted also, 
that while my coefficients are in all cases greater for the iodide 
than for the chloride, Schrader’s are in three out of four cases 
greater for the chloride than the iodide. 
(2) Kay? has recently employed an approximation method 
based upon one previously used by Arrhenius. As a first approxi- 
mation the ionization coefficients of the two electrolytes in a com- 
plex solution were assumed to be the same as they would be in 
simple solutions of concentration equal to the total concentration 
of the complex solution. The total concentration of ions of the 
complex solution (equal to the regional ionic concentrations of 
the respective electrolytes) was then calculated, and gave a first 
approximation to the value of the regional ionic concentration. 
From curves plotted with ionization coethcients of simple solu- 
tions as ordinates and ionic concentrations of the same solutions 
as abscissz, the values of the ionization coefficients correspond- 
ing to the first approximation to the regional ionic concentra- 
tions were read off and formed second approximations to the 
ionization coefficients required. Calculation of the second 
approximation to the total ionic concentration and a repetition 
of the above procedure gave a third approximation to the 
ionization coefficients. In dealing with solutions containing 
sulphuric acid and a neutral sulphate, he found that in general 
the second approximation was so close to the first that a third 
was not necessary ; and he seems to have fourid that the third 
in no case differed appreciably from the second. 
As, in the case of electrolytes with a common ion, the varia- 
tion of ionization with dilution is in general not very different, 
this method may be expected to give very closely approximate 
results. By way of a test I have made a few determinations 
for solutions containing zinc and potassium sulphates, using 
Kohlrausch’s conductivity data. The result is shown in the 
following table in which zine sulphate is indicated by 1 and 
1Proc. R.S. Edin., 22, 502, 1898-99. 
