id ly 
approaches again to 1, after having passed through a minimum value 
at a certain pressure (i.e. a maximum association). In the Arch. Teyler 
08 
(p. 9) L demonstrated that a changes its sign in this case, when 
p | 
v has become = 2 (6, —b,)=b, — Ab. (Av given by formula (8) 
on p. 8 loc. cit. is namely == O then). 
With regard to the influence of the temperature for constant 
pressure, it is easy to see that for 7’=o as well as for p=O the 
dissociation is complete (3—= 1), because y + 1 is always positive. 
But for lower temperatures the behaviour will again be different, 
a 
| Ab (v approaches then 4, so that 
2 
a/b? may be substituted for a/v*) is positive or negative. If this quantity 
is positive [where Ab can be as well + as — (q, is always positive) |, 
the second member of (2: approaches 0 at 7’=— 0, so also 8 approaches 
depending on whether g, + (7 4. 
0 (complete association). But if g, + (» + a Ab is negative (which 
is only possible for A5 negative), 8 becomes again = 1 for 7’=—0, 
so that then a minimum value of the dissociation (maximum associa- 
tion) is passed through. | showed on p. 16 of the Arch. Teyler that 
a changes its sign, when (see also p. 15 loc. cit.) g = q, + YRT + 
€ + a Av=0. The value of 7’ for this minimum will depend 
» 
on the pressure. 
As for 8B=0, 6=6,-+ 846 approaches to 6,, while for B=1 
the limiting value of 6 will be 26,, we may also say that for 
a 
Yo +(e as j Ab positive 8 approaches to 0 at 7’=0O, while for 
1 
do dlp + al Ab negative 8 will approach to 1 at 7=0. 
For all this compare the figures 1 to 4 on p. 6 and p. 18 loc. cit. 
3. Let us now examine the course of an isotherm in a p-v-diagram 
at a not too high temperature, and that first for the case that Ad 
is negative. Then, as we saw above, the value of > approaches to 1 
for p=, ie. h to 2b,, the volume of the simple molecules. So 
this is smaller than 6,. 
The said course is (schematically) represented by fig. 1. (See the 
plate). Besides the usual maximum at 5 and the minimum at /# of 
the ideal isotherm, according to the original equation of state of 
