( 651 ) 
a 
From the equation of state (» + 5) (v — b) = RT we deduce: 
5 
a\/òv dh b) GG da _2adv =, 
(» cv JN =) ca ee v? de ede) ” 
yielding 
or also 
Ow 2af, (v—b)? (4) 
Tei oz 
a a Se ae ay ey OO 
Substituting this in the last equation for apie We obtain: 
av 
o_O, — 2/0 5) 
ears: fae wie) UREA ee 
a (r-5 de ee ce) 
f f RT x : A oe ; 
: da = ; 
since = —2a a nt 2 =f. Further treatment yields after im- 
wv L 
portant simplification : 
= ae le te ((D 
Ou? v = 22/,,(v—b)? 6) 
Comparing this entirely exact expression with that, deduced in my 
. . w= 
former communication, where p and —— were neglected, we see 
5 
that the exact expression (5) is already simpler than the approx- 
imated one, which may easily be written down by means of the 
: : 0? (a 0? a 
expressions for and log —, deduced there. 
dx? \v Ov oe 
4. Consequently equation (4) passes into 
2x (Lr) (av—Bp Ya)? 
u? Fe 2af, (v—b)? y 
RT + 
Ra = 
Proceedings Royal Acad. Amsterdam. Vol. VIL. 
