CED 
same as to take two different constants for pw’, and w',. But then 
we have also: 
Urn = Uo + GC, = Yrs» 
where mu, denotes the value of u, for the first component. 
From this we deduce that the liquid sheet of the saturation surface 
is a plane, and so that: 
P= Pi (le, Sy.) TF Pst, Pe, es 
We deduce this form for p by making use of the relations for 
each of the components: 
D= MRT eo 
Pp, = MRT evt 
Pp: = MRT evo #1 
Wa : : : : . Pp 
The value e * which is constant in this case, is equal to > and 
1 
» By . z Ps 
the value of e “ is equal to >. 
Pa 
The lines of equal pressure for liquids are therefore all parallel 
to each other. If p= p, the projection of such a line is: 
he 
lr — rs j= 
Pam Pa 
ae ae : PaP: 
It cuts therefore the Y-axis at the point y= —. It appears 
Paws 
that in this case we have the interesting circumstance, that the 
addition of a substance with a given maximum tension to a binary 
mixture whose vapour pressure is equal to that maximum tension, 
does not bring about any variation of that pressure, however great 
or small the added quantity may be. 
The other line of equal pressure, the section of the vapour sheet, 
lying at the same height of p, and representing phases coexisting 
with those of the first line, may be deduced from: 
P= Pa (f—7 + Ps + Psi 
if we express in this equation wv, and y, in 2, and y,; and this may 
be easily done if w' and w’, vanish, and wi, and w'‚ may be con- 
sidered as constants. We write then: 
ye } SS ue 
1 2 esa 
— e 1 
BSS ee ip 1 
ha Yo =e 
1—#,—y, aN Lela 
and 
