( 810 ) 
e:g. be one which assumes the shape of a ©, and the isobars of 
still smaller value of p will have broken up into two branches 
each closed in itself (apart from the closed portion starting from 
vl, v=0). C and D (fig. 15) are then the points of intersection 
which have newly appeared; the complication vanishes again in 
Fig. 15. 
consequence of the coincidence of B and C. If the second point of 
contact should arise on the left of the point of intersection lying 
to the extreme left instead of on the right of B a similar result would 
be met with. 
17. At first sight the diagrams of isobars obtained above seem to 
deviate considerably from the figure given by van DER Waats. This 
: 1, : 
is of course partly due to the different course of = == 0. -Pasilyg 
id 
however, also to the fact that the figure loc. cit. only holds for 
27 
temperatures, lying between = of the critical temperature and the 
critical temperature itself. Therefore we find the closest resemblance 
with the figure loc. cit. in our figures for higher temperatures. That the 
resemblance also continues to exist at lower temperatures is imme- 
diately seen when we examine to what changes the figure l.c. is 
subjected with lowering of the temperature. First of all we have 
then the temperature: 
27 a, + a, — 2a,, 
BER 2, 
dp 
av 
As we saw above another point of intersection of ——O and 
