( 545 ) 
of the second kind and the fact that the values of sp and es differ 
so little is in accordance with the fact that it is very difficult to 
prove r.c. II experimentally. 
Let us now proceed to describe the shape of ¢ for the binary 
mixture, in the first place according to fig. 7, so at lower tempe- 
ratures. Let us begin with p< pz, so p smaller than the mini- 
mum pressure of the isothermal of the first component. We assume 
this value of pz to be greater than 0. In this case has ¢ one 
value, at least on the side of «=9. As soon as p is chosen some- 
what greater than pz, there are three values of the volume for 
small values of 2 and so also for 6. If we apply the same consi- 
derations to values of z near «=1, par must be substituted for 
pr. The whole curve consists then, for p somewhat larger than 
pr and pu, first of a continuous curve (vapour branch), and further 
of two separate parts lying on the right and the left, each termi- 
nating in a cusp (see fig. 9). 
Fig. 9. Fig 10. 
If p has increased to the value which the pressure has on the 
line with the loop, the two cusps in fig. 9 have met, and the 
upper branches on the right have coincided with those on the left 
and form two curves with a double point. This is the case which 
I mentioned in note (1) on p. 459. In this case the vapour branch 
lies still lowest, then follows the liquid branch which shows a 
discontinuity, and above it again the branch of unstable conditions, 
also showing a discontinuity, 
