1108 
the pressure and moreover the appearing and disappearing of the 
solid is much liable to retardation. 
To determine the point ¢ still as exactly as possible I used the 
method described below, which offers values, deviating only slightly 
from the real ones. The following figures will illustrate it. 
Fig. 5 gives the P-\ projection of the three-phase line. When we 
Fig. 5. Fig. 6. 
consider a mixture of the composition 2,, which contains more 
naphtalene than is necessary for realizing g, we see that the P7 
projection of this mixture must be as is drawn in fig. 6, in which 
the points a, 6, and c(==q) correspond with the homonymous in 
fig. 5. This section gives the part of the three-phase line between 
hb and c(=q). If a direct determination had been possible, g might 
have been found with this mixture. Although I failed to find g, 
I could study in this section the line of end-condensations, and the 
point of intersection @ of this curve with the three-phase line (see 
table I and fig. 4). 
This point a will slightly differ from q, when z, lies near «,. 
From the distance of dr(Z—=G) from a we can judge whether 
this is actually the case, because in the P7 section #, kr and a 
coincide. The smaller the distance the nearer we are to g. It is 
however possible that the composition along the critical line varies 
only slightly with the temperature, so that in a mixture the com- 
position of which differs slightly from «, dv is nevertheless far from 
a. This proved to be actually the case on studying a second mixture. 
If the concentration of this mixture had been exactly that of g, 
then the PZ’ projection of fig. 7 would have been found. Here the 
point q lies just on the line of the end-condensations. By studying 
the upper branch of the loop-line LG, on which the meniscus dis- 
