972 
When I discovered the law of corresponding states, I could state 
the result in two way —- and in the beginning I, therefore, hesitated 
before making a choice between these two ways of expression: 1. 
“fe . . . v . 
if for the different substances a and m are equal, vr = —— is also 
Uk 
n 
equal, 2. if for the different substances a and m are equal, the 
volume for all is the same number of times the volume of the 
molecules. For so far as I saw then these two expressions were both 
true, and it was after all immaterial whether I chose one form or 
the other. But the first form was more suitable for experimen, and 
the second form would only be of theoretical value — and so I 
chose the first form. In order not to get into great difficulties at once, 
we shall disregard quasi-association for the present, and our result 
will therefore, at least for the present, be valid only for higher 
temperatures and not great density. 
If we write p=ap, RT = RT,m and v= rv;, and if we put 
iy \ 
—— =$, we derive: 
PkUk 
a b 
RA p—— |= ms 
YD PUL VJ 
5 a f-1 a x £ : 
and as we found ———-—=—— or —— =f —1, (These Proc. XIII 
v k R 7 k 7 p ke v ie e 
p. 118) we may also write: 
eS. 
Tale en p= N= NE: 
v Vk 
In our latest investigations we have shown that 
either quite accurately, or with a high degree of approximation. 
Substituting this, we find: 
fot 
nA b 8 f—l 
x+3— ee —— 
p? rhy 3 3 
or 
7—1 
3 BY b 3 
(w+ -)f as B = - ~) = sn 
5 ln men WE ES 
3 3 
It we put, zr, », m==1, we find: 
