( 706 ) 
For the three-phase-pressure both equations hold, and we get the 
dy 
value of = for this three-phase-pressure which we shall indicate by 
- a 
d hie ae 
ae by eliminating dz, from these two equations. If we divide the 
123 
first equations by #,—.w,, and the second by a2, —.,, and if we 
subtract the quotients from each other, we get the well-known formula: 
% — th | Kk? 
dp So dU, AE U, Ls eae | ay 
al ii 5 
dT nn Pati Jet Ven. Ei 
vs U, Us — vy 
: ap 
If we substitute this value of ——— in the two equations given 
( 
123 
we get: 
dp as dx, 
Yai a ee + Ney 
and 
dp fs ae da 
Bant ae = («,—2,) ( 4 ) oa + Ns: 
de, de. Jor dl 
After division by v,, and v,, we may also write: 
d°5 de, 
dp derd ( Op ) 
< al 
Nia Den oT 
2e, 
and 
Os de, 
dp En Op 
AE FF Ys1 3 Gre 
Be, 
or 
dp __(dp\ da, Op 
aT 5, ar a are 
if we represent by & and =) the ratio of the increase of 
rye BD 
p and the increase of 7’ on the vapour sheet of the surface of 
saturation for a section with constant value of «= z,, respectively 
for the coexisting equilibrium between the phases 1 with 2, and 
1 with 3. So the diff dp a Itiplied b zn 
el MN 
with o the difference = fe ar), ultiplied by SE 
1 
