( 808 ) 
on the extreme right side of the figure, returns to a point on the 
liquid branch of 2 0, and then intersects —_ 0 The negative 
isobars, which have their point of intersection with the liquid branch of 
d. dl : 
= 0 still further to the right, again form closed rings round 
Vv 
; d, d 
the second point of intersection of = = 0 and = = 0. These closed 
Vv iid 
rings do not disappear until the temperature has been raised so 
1a dre 2a : 
ae 2 has been reached, which may 
RE 
take place either above the minimum critical temperature of the 
system or not above it, in the first case again either at higher tem- 
perature or not at higher temperature than that at which the point 
: ; ‚dp 
of intersection of ia — 0 
high that the value 
d 
and = = 0 has shifted from the liquid 
Hi 
Vv 
branch to the vapour branch. So different combinations may 
present themselves, which, however, do not differ in essential points, 
and which the reader can easily imagine for himself. 
15. At temperatures at which the double point lies on the vapour 
branch, the loop-isobar, starting from v—0O,2= 2a, passes first 
ARS ‚dp : ; : , 
through the liquid branch of En — 0, where its direction is // v-axis, 
av 
then through the double point, after which it reaches the line # = a,. 
The second branch of the loop-isobar comes from the line «= a,, 
and after having passed through the double point, it pursues its 
dp dp 
course always at smaller volumes than a = 0. In the 
LU v 
isobars with higher value of the pressure only this change has come 
that now a retrograde part appears in the branch at the small 
volumes for a number of isobars, whereas part of the isobars with 
lower value than the loop-isobar fail to have the retrograde portion 
in the branch starting from the line «=2,. They do not get it 
until the value of the pressure has fallen so low that the righthand 
Oa 2a,, 
dp je 
t of — = 0 is intersected. When the temperature — | 
part of — 1S „Intersecte nen the temperature eh 
d 
has been reached, this part of - = 0 has vanished, and so also the 
UV 
retrogression of all these isobars. (fig. 1d). 
The last modification which our diagram may finally undergo, is 
