1204 
curve under its own vapour-pressure of B, the corresponding vapours 
form the vapoursaturationcurve. [Compare also: Equilibria in ternary 
systems XIII, February 1914}. In fig. 6 curve a bcd represents a 
saturation-curve of B under its own vapour-pressure, the corresponding 
vapoursaturationcurve has not been drawn. Now we assume that 
on curve ad occurs a point of minimum-pressure 6 and a point of 
maximum-pressure c; then the pressure increases along ad in the 
direction of the little arrows. 
Now we imagine in the P,7-diagram (fig. 7)a vertical line, which 
corresponds with the temperature 7. It appears from fig. 6 that 
the points a,b,c and d must be situated in the P,7-diagram with 
respect to one another as in fig. 7; of course those four points 
must be situated on the same vertical line; for the sake of clearness 
a small deviation from the true position has been allowed in fig 7. 
In accordance with fig. 6, therefore also in fig. 7 at the tempe- 
rature 7, the pressure first decreases starting from a as far asin b, 
ing from 6 up to e and 
further it decreases again 
starting from c as far as in d. 
The points hand c are drawn 
in fig. 7 within both the 
limit-lines; it is apparent, 
however, that 4 might be 
situated also below curve 
dn and that ec might be 
situated also above curve a /. 
Now we take a tempera- 
4\ ture 7; the saturation-curve 
Fig. 6. under its own vapour-pres- 
sure is represented in fig. 6 by curve eh; it has a point of minimum- 
pressure in f, or point of maximum-pressure in g. We find the 
corresponding points in fig. 7. 
Now we assume that on increase of 7’ the point of minimum- 
and the point of maximum pressure of the saturation-curve under 
its own vapour-pressure come nearer to each other and that they 
coincide at 7; in the point S. Then the pressure increases along 
curve iSK (figs. 6 and 7) starting from K towards 7. In the P,7- 
diagram the points 7, S and AK must then be situated with respect 
to one another, as in fig. 7; it is evident that the point S must be 
situated between the points 7 and K. 
At temperatures above 77, e.g. at 7), the saturation-curves under 
afterwards it increases start- 
