(9) 
! 
sig los PD 
le te and, 
p dy, 
‘ ry > ! € a! ’ AN ‘ 7 
so the dependence of w'‚, and «', on the coordinates x, and y, is 
reduced to the dependence of the coincidence-pressure on x, and y,. 
The coincidence-pressures would be the maximum-pressures of the 
different mixtures, if they behaved like simple substances. The fol- 
lowing relation exists for the coincidence pressures, at least approximately: 
Consequently we find: 
VA Cs dlog per 
+- EES 
eN Ne ee 
re ie da, da, 
' UE aT, d log per 
and Un SO ee 
4 ff dy, dy, 
; Vee dilog: Ter d lod per 
or Fe ese Ae et TEES ee tome IM) 
oa Ml du, da, 
OGL ox d log Por 
ce spe cee OR Aa 
grey: dy, dy, 
It is clear from the deduction that these formulae may only be 
considered as an approximation for the case, that the vapour-pressure is 
low, and therefore 7’ much lower than 7. Putting f == 7 we may 
put the factor of the first term at a value of about 12 or 14, and the 
; ad bon Le 
factor of the second term is unity. If therefore the values of ——— 
wel, 
d log Tey _ d log per d log per 
and — — have moderate ratios to those of —— ‘ Ss 
dy, da, dy, 
we find for u a course not differing much from proportionality to 
dT 
dx, 
in which I had obtained it before (Cont. I, p. 148 ete.) But in the way 
we have now followed we are enabled to add a correction term. Of course 
these equations (5) and (6) are only approximations, and that, for several 
reasons. But we must distinguish between the character of these appro- 
So we obtain a result in a way, totally differing from that 
ximations. In the first place we have assumed that «’,, and w',, vanish 
for a vapour phasis, and so that u for different mixtures at the same 
pressure has the same value. If the density of the vapour phases is 
so small, that they do not perceptibly deviate from the laws of Borin 
and Gay-Lussac everyone will agree that this approximation may be 
admitted. In the second place we have ascribed to uw for the liquid 
