1308 
one of the three components; the distillation curves of the liquid 
then become straight lines, those of vapour and distillate are reduced 
to a single point. 
When a distillation curve of a liquid meets the saturation line of 
I’ under its own vapour pressure in the point 4, it will not penetrate 
within the heterogeneous region, but meet this saturation curve in 
b; its vapour distillation curve will then also meet the vapour satu- 
ration curve. 
Among all distillation curves intersecting the saturation line of 
under its own vapour pressure there is one that behaves in a parti- 
cular manner: it is the one that intersects the saturation line in 
the point M/ and, therefore, meets the line MM, in M. If we with- 
draw from the liquid J/ a little of the vapour J/,, M will not 
change its composition, but the reaction: liquid J/—solid /+-vapour 
M, will appear. If now the vapour is continuously distilied off, the 
liquid M will disappear without change in pressure and only the 
solid substance / will remain. The distillation curve arriving iv M, 
therefore, terminates in this point without proceeding any further 
along tbe saturation curve of £. 
What follows next is dependent on the temperature; this, as we 
have presupposed has been chosen lower than the minimum melting 
point of #. We now can distinguish two cases. 
1. The distillation temperature is higher than the maximum subli- 
mation point of /. The saturation curve and the vapour saturation 
curve of F under their own vapour pressure then possess a form 
like in fig. 7(D, the isothermic-isobaric diagrams are as shown in 
figs. 1 (D—6 (J). 
After, on distillation, the liquid J/ has disappeared and only the 
solid substance F’ remains, the pressure conforming with fig. 2 (f) 
will fall to the pressure to which fig. 5 (I) applies. At this pressure, 
the reaction solid FZ liquid m—+ vapour mm, now occurs. If now 
the vapour is continually Criven off, the solid substance / will dis- 
appear and the liquid m will remain, without any change in pressure. 
On further ‘distillation. the liquid transverses the distillation curve, 
starting from point m in fig. 3. 
The liquid, therefore, proceeds first along a distillation curve 
terminating, at the pressure Py, in the point M, and then along 
another one starting from m at the pressure P,, ; at the transfer of 
the liquid from the one to the other distillation curve, hence, 
between the pressures Py, and P,,, it is converted into the solid 
substance #. 
2. The distillation temperature is lower than the maximum sublimation 
