( 686 ) 
ow dw dw | 
ee oe + (%2—2) ae + (ya) Hay mee | AM ae FS 
we may write this equation in the following form: 
dv,\ dv,\ - 
(a) ay) — on (Ft) =o © 
i) 
The equation is reduced to this form, if after division by de 
oy 
we take into account, that for constant values of y and 7: 
dp Op 
ip is 
ap dv + a d. 
or 
nd =) op 
~~ Ov \da On 
or 
RDR tee 
~ Ov? \ar p dev 
And also that 
ssh dw fe dw 
ie (ans 
Written in the form (@) a property of the tangent point phases proves 
to be (see for a binary system Cont. II, pag. 109) that the mixing 
of a finite quantity of this phasis with an infinitely small quantity 
of the coexisting phasis to one homogeneous phasis, 7 and p being 
constant, involves decrease of volume, which is infinitely smalleven 
compared with the infinitely small quantity of the second phasis. 
If we write (a) in the Pad form : 
0 0 
me) B+ (eee) SP + Wa na, =. en 
and if we take for the length of ihe line, connecting the two phases, 
the positive quantity Z, then no difference of pressure will exist 
between ihe tangent point phasis and a phasis whose difference from 
it is given by the quantities dv,, dr; and dy), such that: 
dv; de, dy, dl F 
En SS Se = ee ae 
Sg UL) Ha ee hy are L 
equation (7) namely may be represented in the following simple shape 
d 
Le = 
dl 
If we construct a surface of constant pressure through a tangent 
point phasis, the line joining the nodes will be a tangent to that 
surface. (See for a binary system: HARTMAN, Proceedings III, p. 66). 
We have to distinguish different cases, if the critical temperatures 
do not agree with the condition we have mentioned. If 7c, has a 
