( 282°) 
solid A and with solid 5 meet each other in the point /. In the same way, 
two other liquid-surfaces must join in the point Zat which the liquid 
surface coming from higher temperatures ends, namely those which 
indicate the p,f,# values of the liquids which can coexist with solid 
A or solid B. The lower limits of these surfaces are the lines O4H 
and Op which represent the equilibrium of solid and vapour. Set- 
ting out from these lines the vapour disappears when the pressure is 
increased. On account of the small changes which the composition 
of the liquid undergoes with an increase of pressure, the liquid- 
surfaces O4HEPU and OgEPV will rise almost vertically. They ter- 
minate to the left and the right in the melting point lines O4 V and 
OpV of the solid substances A and B, whilst they intersect each 
other in the line ZP which indicates the liquids which at different 
p‚t values can coexist with solid A and 5. To this line belong 
the p,¢ lines GQ and HR for the solid phases, which again form a 
cylindrical surface with EP. 
In this way we arrive for the complexes of solid A + liquid at 
the space included between the liquid-surface, the surface of the 
solid A, O4 UQG and the cylindrical surfaces GO, HE and GEPQ. 
A similar space includes, at the right, the complexes for solid 
B + liquid. 
Finally, the region of the complexes of solid A + solid B is situated 
behind the cylindrical surface GHRQ and above the cylindrical sur- 
face NHGM. 
The spaces last described terminate in the figures at the back at 
an arbitrary temperature and above at an arbitrary pressure. One 
must suppose that, in reality they continue their course. 
The remaining space outside the massive parts constitutes the 
regions of homogeneous liquids and vapours which pass into each 
other beyond the critical curve. The other six massive parts repre- 
sent complexes of two phases, the states of matter forming the complex 
being represented by two side surfaces. 
They further are connected with each other by four cylindrical 
surfaces on which three lines are always situated representing 
the systems of three coexisting phases and these cylindrical surfaces 
intersect each other in one straight line on which is situated the only 
possible complex of four phases. 
If for any system of two substances the figure described were 
studied completely, it would enable us for each mixture at each 
temperature and each pressure to read off, of what phases it has been 
built up and as far as liquid and vapour are concerned it would 
also show their separate composition. 
