683 
lowering of the point of solidification, and from that of the point of 
transition on analysis of the coexisting phases and on measurement 
of the thermal quantity Q. 
Roramunp, who examined the system CBr,—CCi,, has not succeeded 
in determining w, and z,. He could not 
observe the range of solidification, and 
only found the lowering of the point of 
solidification proportional to the total- 
concentration. Nor did he know the 
value of Q, so that he could not test 
formula (1). 
On the occasion of his examination of 
the system HgJ,— Hg Br,, Reivers’) used 
Rotamunn’s formula for the first time 
applying it to the lowering of the trans- 
ition point. 
As ReEINDERS’s research was not ex- 
pressly undertaken with a view to testing 
MG RornMUND’s formula, and as it was not 
accurate enough for this either, it can only be concluded from this part 
of his interesting treatise that probably Rorumunn’s formula will be 
confirmed here, and that when it is assumed that here really a 
definite conclusion can be reached with regard to a molecular size, 
it will lead to the result that the molecular size of mercury bromide 
is the same in the two mixed crystal phases. 
It follows from the foregoing that there was still a large lacuna, 
and that we were not at all able yet to say to what results the 
application of the let us say, limiting laws, to the equilibria with 
mixed crystals, lead. 
And because it is the study of the diluted mixed crystals that will 
be able in my opinion, to give us a deeper insight into the solid 
state, I resolved to set on foot a most careful inquiry into the 
question whether the law of partition also holds in case of coexistence 
with mixed crystal phases. 
It was to be foreseen that the investigation would be very difficult 
and laborious, for reliable results can only be expected when the 
mixed crystal is perfectly homogeneous, so that the internal concen- 
tration is the same as that of the surface. In order to bring this 
about it was necessary that the formation of the mixed crystals 
should take place exceedingly slowly amidst vigorous stirring. 
1) Zeitschr. f. physik Chem. 32, 494 (1900). 
