( 909 ) 
the right half of the diagram of isobars of vaN per Waars, when 
we think it drawn above the minimum critical temperature and 
Fig. 21. 
27 a, + a,—2a,, 
Benen 
below the temperature (cf. $17). At the latter tem- 
‚dp d, ; 
perature the point of intersection of LQ and ~—0 has vanished, 
Lk v 
; $ a, + a,—2a 
and so also the closed isobars round it; at the temperature ——— 
b, = b, —2b,, 
the line 20 itself has left the region under consideration moving 
continually to the right. 
2nd Case. If the a-line is shifted to the left, we get fig. 22, 
from which the course of 7, and pz follows naturally. This case is 
distinguished from the preceding one only in this, that we get fig. 23 
instead of fig. 21 at low temperature. This figure presents a close 
resemblance to the right half of fig. 13; we have reproduced it 
separately here to draw attention to the fact that now none of the 
isobars of high pressure, as is the case in fig. 13, reaches the point 
v=0, «=x,. All the isobars of fig. 23 reach the line «= 2, fora 
positive value of v. This is in accordance with a remark which we 
already made in §8. For in the case now under discussion the a 
db 
de” 
dsobars passing through the point v=0, # ==. So these isobars 
: 7 eh dv 
is negative for «= wx, and this involves that (ze) Ge for the 
a}, 
