( 300 ) 
VAN DER WAALS’ equation: 
DT 
p+ (v — b) = MRT 
ye 
as well as CLAUSIUS’: 
Bey eta ss See 
oF CHE = | 
EE Bok oO (==) == 
I would also have availed myself of the equation of state given . 
by Dierericr (DRUDE’s Annalen Bd. 5 p. 51—88, May 1901), but 
found that there has crept an error into the oes DE this to which 
I draw attention in the following section. 
give : 
eng. es ; : ; 
§ 4. DIETERICI puts p = = in which vq is derived from v 
Va af a 
by means of the equation: 
Va 
dv ve Ty? 
fsa=-2 qi) 
v 
1-6 2 
bard be Sg Mh 
where a is a constant to be calculated for each substance from the 
critical data, for instance for isopentane a = 2.116. 
From these equations we find: 
T /òp 3 UE ne, 1 vz 
eae ek zl ae LEE 
- Gi), tres uil 
which for the critical Ben, becomes 
dp yi 3 ( 1 u?) 
GE 
