( 461 ) 
For the pressure of that straight line we should get according to 
the law of the corresponding states the relation 
If the law of the corresponding states should not be applicable, 
the shape of the function p would be variable with x and y, and 
Per and Ter also being variable with rz and y, there will be only 
one relation between zr and y at given 7 and p. This relation 
given under the form 
n= Re) 
gives the equation of the locus discussed. For our purpose we shall 
suppose, that it is represented by a single continuous curve, running 
from a point of the z-axis to a pointon the y-axis. 2rd the projection 
of the points, representing coexisting phases, and consisting of two 
branches one on either side of the curve mentioned sub 1st. This 
projection is not the projection of the points B and B'. It is namely 
obtained not by tracing a double tangent at the É-curves, but by 
construing a double tangent-plane at the two sheets of the ¢-surface. 
In general this locus lies outside the projection of the points B and B' 
except in the axes when it coincides with it. 34. The projection of 
the points indicating the limit between the metastable and unstable 
hases, so of the points for which Oe see (2): — 0 This 
ig x ax dy? Nar) 
locus does not coincide with the projection of the points # and LZ’; 
only in the axes it coincides. 4. The projection of the points D 
and D', so of the points for which at the chosen temperature the 
pressure chosen is equal either to the maximum pressure, or to the 
minimum pressure of the isothermal drawn for homogeneous phases. 
So with this configuration we can speak of a connodal curve and 
also of a spinodal curve; but the spinodal curve need not lie between 
the connodal curve. 
Let us now increase the pressure, then the crest, lying above 
the line of the double-points, will decrease, and of course it will 
change its place, and let us assume the pressure to be greater than 
that of the point K (fig. 2) for one of the pairs of components. 
Let us choose the pair represented by the y-axis, then the line of 
the double points has retired, so that is ceases to exist somewhere 
in the ay-plane. If moreover the pressure is higher than the plait- 
