1203 
according to our previous considerations the. pressure increases’ from 
F towards Z and decreases towards 7, the vapour pressure curve 
in #” must have a direction like curve af’h. As the line FZ comes 
into contact with one of the exphased boiling point lines, the pressure 
in this point is a maximum; on the curve a”? of fig. 2a maximum 
vapour pressure must, therefore, occur somewhere between a and /’. 
If, however, the line ZFZ, of fig. 1 is turned in. such a manner 
that it keeps on passing continually through /’, the curve al’) of 
fig. 2 will change its form although it wiil of course, also keep on 
passing through /”. From our previous considerations it follows at 
onee that the direction of the tangent in #” and the position of the 
point with maximum vapour pressure changes. If Z/Z, coincides 
with AY we obtain in fig. 2 a curve cf#’d with a horizontal 
tangent in ZY. 
We have assumed in fig. 1 that the boiling point. line passing 
through is curved in the point F in the direction towards D; 
in our previous communication (II) we have noticed, however, that, 
in the vicinity of # it may be curved in some other direction also. 
It may then present a form such as curve afb of fig. 2 (ID in 
which, however, we must imagine the arrows to point in the opposite 
direction. We have deduced this form while assuming that the 
vapour contains one of the three components on!y. Although in 
this case, the appearance of such a form is not very likely, 
the possibility thereof is greater when the vapour contains the three 
components and when, for instance, in the system LG a maximum 
temperature occurs. We now imagine through point / of tig. 1 and 
also at somewhat higher and lower pressures, boiling point lines of 
this form. Lines proceeding from /' towards that side of VF Y 
where the point D is situated will then each again come into contact 
with a boiling point line, so that a pressure maximum must occur. 
Lines which proceed from # towards the other side of X/Y either 
do not come into contact with a boiling point line at all, or else 
they meet two of these, so that there occurs one point with a 
maximum and one with a minimum vapour pressure. The latter 
case will occur on lines in the vicinity of FX and FY. 
On turning the line ZPZ, of fig. 1 we will, therefore, have vapour 
pressure curves like af’) of fig. 2, further like af’) of fig. 3, and 
if ZZ, coincides with XFY of tig. 1, a vapour pressure curve 
ch’d of fig. 3. 
In order fo investigate the change in temperature in the point 
fF on the lines passing through this point we take the formula 
corresponding with (8) : 
