862 
again indicate the direction in which the vapour pressure increases. 
The previous considerations relate to the saturation line under its 
own vapour pressure; in a similar manner we may likewise inves- 
tigate the boiling point line of the saturated solutions. We must then 
in (26 iace A by gu in whicl BEE 
in (26) repiace A by u in which HE 
Instead of Q—AS we must then consider Q—u 5. u is now always 
positive and as regards absolute value smaller than 24. Further we 
must replace AdP in (22) by Bd7. As, moreover, the line OF must 
intersect the boiling point line of the saturated solutions in a point 
between O and F, we re-find the cases represented in figs. 1 and 2 
in which a/b now represents the boiling point line of the saturated 
solutions. If, however, the arrows must indicate the direction of an 
increasing temperature one must imagine them to point in the 
opposite direction. 
If we compare the values of Q--A S and Q—u S in regard to 
each other, we may search for the different situations of the satu- 
ration line under its own pressure, and for the boiling point line of 
the saturated solutions in regard to each other, in the vicinity of 
point #. I will, however, not go in for this now; I will, however, refer 
dP . ENE 
to it when discussing the value of an the vicinity of the point #. 
Whether all conceivable combinations are actually possible is diffi- 
cult to predict. Perhaps a solution might be found by introducing 
the condition of equilibrium of vaN DER Waats and expressing the 
different quantities in the a and 6 of vaN DER Waars, which must 
then be considered as functions of w and y. 
We will now deduce the vapour saturation lines under their own 
pressure and the boiling point lines of the saturated solutions yet in 
another manner. 
iy 
Fig. 5. 
