( 323 ) 
F'(p) is therefore always negative; the further we therefore get 
from pi, in other words the smaller p becomes, the greater becomes 
F(p). So if the isothermal is first concave, it can become convex 
further on, but it cannot be convex at a certain value of p and 
become concave at a smaller value. 
Let us now examine for which mixtures the inflection point, 
which has entered the isothermal at # = 3, has reached the other end 
and we accordingly pass from the case of fig. 211 to that of fig. 2 IIT. 
Hic, 21, - 
Fig. 2 IIL. 
It is obvious that the pz for this point must be greater than 
1/,(p4+ ps), for then the first term of F'(p) is positive, so a 
fortiori the whole expression. In order to find the exact point 
where the inflection point makes its appearance we substitute in: 
