( 639 ) 
the value of 4 becomes considerably smaller. If e.g. we take g, a 
hundred times smaller than in our former example, i.e. g, = 32, 
we have the following values (Ab = 0,5): 
C2, a {both Epes) 0, 1, Qbe = De ae 2700; 
The value of 2b,= 0, + Ab (liquid) is now not 1—0,5 = 0,5, 
but 1 + 0,5 =—1,5, i.e. greater than that of 6, (solid). The critical 
temperature (vapour-liquid) is found from: 
8 
(1+ ART = zj, 
assuming that for 7’. all the double molecules are dissociated, hence 
8 2700 1600 
a 
b has become = 2b,. This gives GA) 41. = 57 PE , 80: 
400 
T, =~ = 188, 
In our former example, where Ab —=—¥‘/,, and so 2b,=1'/,, 
T, was = 400°. j 
Pe oil 2700 400 
The critical pressure now is p‚ = 37 (2b, aoe X a, aK 
=44"*/,, 
instead of 400 for Ad = — 0,5. 
26. Now we proceed to the more accurate calculation of the 
coexistence-curve solid-liquid for 
Ab=0,5 (6, =1, 26, = 1,5), 
indicated in fig. 23. 
The successive isotherms, belonging to the different points of the 
curve PQSRCr in fig. 28, are represented in the figures 27—382. 
In fig. 27 the stage below the point P, where coexistence vapour- 
solid is only possible (on the line OS of fig. 23). In fig. 28 the point 
of inflection D,C' appears (F in fig. 23), and somewhat later (fig. 29) 
the first coexistence liquid-solid (the point Q in fig. 23). As this, 
however, takes place at negative pressures, the said coexistence is 
not realisable, and for the present only the coexistence vapour-solid 
is found as in fig. 27 and 28. 
Only at still higher temperature (e.g. the point A in fig. 23) the 
coexistence liquid-solid has become realisable (and this already starting 
from the triple point S), which is represented in fig. 30. Now we 
have at first vapour-liquid, and at higher pressures liquid-solid. In 
fig. 31 the critical poet liquid-solid (Cr in fig. 23) appears, after 
which (fig. 32) no coexistence liquid-solid js possible any more. Then 
only vapour-liquid remains — till at last this too disappears at the usual 
critical temperature (vapour-liquid). 
