( 601 ) 
2. It appears from the fact mentioned in 1 viz. that the diagram 
of isobars of fig. 1 loc. cit. in connection with the theorem of 
VAN DER Waals mentioned excludes the possibility of a minimum 
critical temperature for the case a,, =4,4,, whereas after all also on 
this supposition a minimum critical temperature is not impossible, 
that the diagram of isobars mentioned is- not the only one possible. 
Now the shape of this diagram is in the first place controlled by 
d ep 
the line and the question suggests itself if in general another 
x 
shape of this line is also conceivable. In the determination of its 
course it was derived from the equation: 
da 
eter hee 
SB eet Leb 
PEN MRT — 
da 
that an asymptote must exist for the value of xv determined by: 
da db 
Ss ERT 
de da 
and that to the right of this point everywhere a positive value of v 
greater than b is to be found satisfying this equation. In this it has 
db 
da 
been tacitly assumed that for the value of x, for which ae MRT a 
v & 
b is still positive; for if 6 were negative at this place, only a high 
negative value of v could satisfy for the values of 2 somewhat larger 
: f da db dp 
than that for which — — MRT —, and hence the course of — =0 
dx dx dx 
would become an altogether different one. So though naturally that 
value of & for which 6 becomes =O, can never lie within the 
realisable part of the diagram of isobars, it yet appears that the situation 
: ; dp. + Se 
of this point can determine the course of ae and with it of the 
at 
isobars in the realisable region. 
3. In the complete (extended) diagram of isobars such a point 
must probably always occur. This is self-evident if we should be 
justified in considering the dependence of 6 on « as linear, and it is 
also easy to show it if we assume Lorentz’s well-known formula 
for b,,. For then: 
Pe (SV ON 
12 2 
