1201 
shifted to that side of / where the vapour region is situated. On 
increase of pressure, the boiling point line disappears finally in the 
point J/, the correlated vapour line in the point J/,. The point 
D indicates the vapour which can be in equilibrium with the solid 
substance / and the liquid /’, therefore the vapour which forms at 
the minimum melting point of the compound /. The line XFY is 
the tangent in # at the boiling point line passing through /. We 
have already noticed previously that the lines DFE and XY are 
conjugated diagonals of the indicatrix in / at the liquidum side -of 
the ¢-plane. 
We now lay down through # an arbitrary line ZZ, and let a 
liquid proceed along this line; as according to (6) dP and dT’ have 
a definite value differing from 7/ it follows that in this point neither 
the pressure nor the temperature is at a maximum or a minimum. 
If, however, we choose the line in such a manner that 
Or + (Be + a, Oe + Y—B gp =O. © (7) 
then dP as well as dT is nil. From (13) (1) it follows that (7) is 
satisfied when the line drawn through #' comes into contact 
in # with the boiling point line passing through this point, therefore 
when the liquid proceeds along the straight line X/Y. 
If now we introduce a line element dg positive in the direction 
away from / and negative in the direction towards #, and if we 
let p change from O° to 360° we have de =cosp.de so that (6) 
is converted into: 
Bl ert (WAM oor + eet (HAMIL og 
BC— AD oy 
= 
The factor 
{(v,—a)r + (y,—B8)s} cos w + \(a,—a)s + (y,—B)R sing … . (9) 
in the point Fis nil towards X as well as towards J’; in all other 
directions it differs from „il. If to p is given such a value that the 
line passes through ‚the point D we notice that the factor (9) is 
positive. Hence, in the point / the value of (9) is positive in the 
direction towards D and negative in the direction towards Z. 
We may now easily deduce that (9) is positive if, starting from 
I’, we move towards that side of the line X/’Y where the point 
D is situated; and that (9) is negative when we move from F 
towards the other side of the line X/Y. These positive or negative 
values are, however, very small if the direction almost coincides 
with FY or FY so that at some distance a reversal of the sign 
may perhaps take place. £6 = H—y being positive it follows from 
(8) that the pressure when starting from /” increases towards that 
{hoi 
