( 801 ) 
quantities will get an entirely different value depending on whether 
b increases with z or with z°. Thus the critical temperature becomes 
infinite in the first case, in the second it approaches a finite amount, 
the critical pressure becomes finite in the first case, zero in the 
d, d 
second, and also the situation of ! — 0 with respect to 0 
, av ar 
is quite different in one case from that in the other. For if we 
substitute in the equation: 
dp MRT 2a 
- EO) = — — => —_—>7- = 
dv = (v—b) v 
d 
the value of v——b, as it holds for ? = 0, we get: 
dx 
da 
dx 2a 
F = see 
Ole ache 
dz 
Now we may put a, 2’ for a for very great value of «, 2a,x for 
da db 
= and 26,2 or 6, for En depending on whether we assume the 
av wv 
quadratic or the linear form for 6. In the latter case: 
a afb, 
: GEE v? ( aaa 
dp dp 
so positive, so that — — 0 is found in the region where =, 8 negative. 
at ‚U 
In the former case we get: 
a, (v—2b_,x' 
a se De ) 
ue 
d dp, 
so that = = 0 is found in the region were is negative (the stable 
v av 
region of the mixtures taken as homogeneous) only if» > 2b, which 
according to the known properties of the isotherm comes to the 
dp ee 
—— == 0) | 18-posifive, 
l 
same thing as that the pressure in the minima ( 
av 
27 es 
or the temperature higher than rs of the critical temperature. 
11. Let us for the present confine ourselves to the supposition of 
a quadratic function. So in the case which is still under considera- 
tion that there is minimum critical temperature and yet a’,, > a,d,, 
i 
