1038 
In the determination of 4 we are only concerned with the number 
of ions present in a certain volume of the solution so that the said 
perturbing factors exert no influence on the calculation of 7. The 
relation ill therefore indicates the actual value of 7 when V repre- 
Ax 
sents the reciprocal value of the number of gram-mols per 1000 ce. 
of solution. 
I have endeavoured to ascertain, by the measurement of A the 
depression of the solidifying point and the rise in the boiling point at 
equal concentrations and temperatures, in how far these considerations 
are in agreement with the result of 7 in the case of NaCl, KCl, MgCl, 
and CaCl,. The arrangement of the experiments did not admit of 
making direct experiments at equal concentrations. I have, therefore 
approximated the values of 7 as accurately as possible by graphic 
interpolation. Properly speaking I ought to have determined 4 at 
the solidifying and boiling points of the solution instead of at O° and 
100°. As, however, the change of 7 with the temperature is very 
slow, this correction would not counterbalance the inaccuracies which 
would then be introduced owing to the great experimental difficulties. 
I have also occupied myself with the calculation of 7 from satur- 
ated vapour determinations of saline solutions, were we can expect 
the same divergencies as in the dynamic determinations. Notwith- 
standing detailed and laborious experiments I have not succeeded in 
obtaining, in this manner, results sufficiently accurate for controlling 
the above mentioned values of 7. I will only mention that 7, when 
accurately determined within one decimal, gave the same results 
with the statical and the dynamical method. 
In the “Chemisch Weekblad” (1915) will appear a more elaborate 
description of the apparatus employed by me and the corrections 
applied for the calculation of 7, whilst the agreement and the dif- 
ferences of my results with those of other observers will also be 
discussed. 
The following points of a more general importance, I wish to 
mention here. 
The manner in which the conductivity power of the water, used 
in the 4 determinations, is computed is generally carried out by 
multiplying the specific conductivity power of the water with the 
dilution of the solution expressed in cc. 
This empirical method, however, keeps no account with the position 
of the sliding contact on the measuring bridge. The following 
deduction may demonstrate, however, that this position exerts a strong 
influence on the correction to be applied. Suppose : 
