( 457 ) 
We shall therefore not avail ourselves of this means for the 
determination of the modification of the ¢-curve which is the conse- 
quence of increase of pressure. We shall go back to fig. 2 and 
through the projection of the connodal curve of the w-surface drawn 
there we shall draw a curve for which p is greater. Without actually 
tracing the lire it is easy to see that as long as p has a value 
below that of the isobar which would pass through 4, the retro- 
gression of 2 will continue, and so also the branch DD' in fig. 3. 
Only its limits and so the values sp and xp’ will approach each 
other. For the isobar of K the retrogression has ceased. This 
curve of constant pressure touches the locus CKC' and the common 
tangent is parallel to the v-axis. As a point of inflection must occur 
between D and D', we conclude that the isobar of K must have a 
point of inflection in the point K. This isobar still cuts the spinodal 
curve twice and the ¢-curve for that pressure will retain its two 
points of inflection. Consequently the great complication will not 
disappear from the ¢-curve till we get this pressure. We shall 
henceforth use the name of crest for the configuration which lies 
above the double point. So we may say that the crest has dis- 
appeared for pressures greater than K, whereas it remains for pres- 
sures smaller than A. If we now trace the ¢-curve again, there 
is only in so far a complication in this line, that it contains a 
concave part with two points of inflection, and so that there will 
still be a double tangent. It is proved here in another way than 
follows from the theory of the w-surface that the critical pheno- 
mena will make their appearance in a mixture only at pressures 
and temperatures, which are higher than when we had to deal with 
a simple substance. But paying attention to the way in which we 
have arrived at this result, we see that we have only been able 
to derive all this by means of the knowledge of the w-surface. 
And this is the reason why I have formerly made use only of the 
w-surface and why I have considered the ¢-curve not suitable for 
leading to the knowledge of the critical phenomena. 
If the pressure is still higher, the two points of inflection of the 
¢-curve draw nearer to each other; and when the pressure reaches 
the value of the plaitpoint-pressure, the concave part of the curve 
disappears and the ¢-curve has turned its convex part downward 
every where. 
In what precedes we have discussed the way in which an existing 
complication in the ¢-curve disappears. Let us now examine what 
happens when such a complication extends. 
Let us for this purpose examine, what will be the consequence, 
