( 900 ) 
be indicated, and though it will diverge greatly for the different cases. 
At the temperature of the splitting up the point C lies on the 
binodal line of the equilibrium liquid-vapour. This point is then at 
the same time the plaitpoint of the detached plait, which we may 
call longitudinal plait, and which also possesses a binodal curve for 
BRL jee ‚db 
the equilibrium of two liquids. If FE > 0, in accordance with which 
at” 
I have drawn the line v= curvilinear, this longitudinal plait is 
closed. Then the spinodal line of this longitudinal plait, which has 
also been drawn in fig. 45, has a point with minimum volume, 
2a, 
, dv 
where it passes through Se —0. There are also points where 
at 
q 
dv : : dv ae dv ; 
=, i.e. where it cuts | — }=—0. The sign of | — is 
da Spin da p da Spin 
determined by the given differential equation, and quite corresponds 
; ‚dv dv dv : 
with the values of — , | —_}=O and { — |=0 in fig. 45. The 
dt, \da° ; dzx* }, 
, 
a ref 
value of (= is always positive, because this spinodal curve lies in 
le) 
dp ws 
the region where {| — | > 0. And the signs of the two other quantities 
Ak v 
are negative inside and positive outside the limits for which they 
are 0. For this longitudinal plait there is indeed equilibrium between 
two liquids, but not with a third phase. So it lies altogether outside 
the region of three-phase-pressure. 
If we trace the p,z-line for the equilibrium liquid-vapour, both 
dp dp. E 
a and autre equal to O for the point C. At somewhat lower tem- 
wv TL 
perature, viz., longitudinal plait and transverse plait overlap slightly, 
as they both extend with decrease of temperature. Then there is, 
indeed, three-phase-pressure; then there is coexistence of 2 liquids 
and vapour. The metastable and unstable branch, which exists for 
this equilibrium between the two coexisting liquids, has a minimum 
and a maximum. In the point C not only the two points of equal 
pressure coincide but also the minimum and the maximum pressure. 
In the v,z-projection of the binodal curve for the equilibrium liquid- 
vapour we have in the point C: 
dv on dv 
de bin De da: Pp 
d?v 2 
e == ike = 0, 
da*) ym \de*), 
and 
