1541 
Of more importance is the question what will be the shape of 
the internal equilibrium lines of the unary system in the P,X-section. 
We see then that according to PLANck’s formula 
dink Av 
dp re RL 
this displacement will be determined by the sign of Av. 
Now we have supposed here that the pseudo-components are 
isomers, which of course involves that the P, X-line for the internal 
gas equilibrium runs vertical. This does not apply, however, to the 
lines which relate to the internal equilibrium in the liquid and in 
the solid phase, because the b-values from VAN DER Waars’s equation 
of state for isomers, are not equal on the whole. In the following 
figures the P, X-lines of the unary system have, however, been drawn 
vertical in all the phases for the sake of simplicity. 
First of all we shall now consider the P, X-section at the tem- 
perature t,. The thin lines again indicate the pseudo-binary figure, 
the thick ones the unary figure. 
» 
Su, 
