( 135 ) 
[For the coexistence liquid-vapour, instead of liquid-solid, this 
relation would pass into 
y «/ b2 _ pv' , % 1+2^ 0 z b i— b > L 
109 p ~(l+F)RT^ RT 1+<J ^ v-b +h9 {l+p\-p) 
for sufficiently low temperatures, when v (liquid) may be neglected 
by the side of v' (vapour), — by the side of —, and t ~ by the 
or it may pass into 
,•!* % h-v, • - a+fl». 1 ln 
h 9 T~ rtT+?+ —b — + 109 i-ftl'’ 
p*' A _ nA-A 
because - - - == 1 and 1 — 2£ -— = - - - = 
(l-\-p)RT *—b v-b 
If now moreover ft = 0, = 0, so that we have to deal with a 
simple substance, this (b = becomes: 
van der Waals’ well-known relation for the pressure of coexistence, 
as viz. %3 may be expressed in p c and »/„ in T c (see Teyler, 
p. 36—37)J. 
14. Let us return to the coexistence liquid-solid. The formula 
(16) holding for this might also have been found from the relation: 
in which now the quantity £ must be assumed to be variable in 
the integration between v and v'. But this course would have been 
far more lengthy, because then we should also have had to make 
use of the relation of equilibrium (2) [see I, p. 770]. We have, 
however, convinced ourselves that the result, as might be expected, 
is identical with (16). 
As v and v' may be eliminated by means of the equation of state, 
i? and by means of the relation of equilibrium (2), the derived 
relation (16) is really the required relation p=f(T). But unfortu¬ 
nately these eliminations cannot really be carried out, so that we 
have to restrict ourselves to deriving the value of the pressure of 
