(147 ) 
point of He Bro, to 255°.4, the meltingpoint of Hgls, possesses 
a minimum at 216°.1 and 59 pCt. (molecular) of Hg Br. In this 
minimumpoint the mixed crystals have the same composition as the 
fused mass. 
To the right of this point the crystals contain more Hgl,, to the 
left of it more Hg Brg than the fused mass. The differences are, 
however, not large; the line 
of the erystals (lower curve 
ACB) lies close beside the 
meltingpoint line (upper 
curve ACB), | 
Below 216° therefore, 
mixed crystals of any com- 
position are capable of exis- 
tence. hey belong to the 
rhombic system. At 127° 
pure Hel, is transformed 
into red, tetragonal crystals, 
(point DP), 
This transition point is 
depressed by admixture of 
HgBro. Further, it develops 
into a transition interval, 
bounded by a line DE for 
the yellow crystals, which 
runs from 127° and 0 pCt. 
Hg Bry to 0° and 33 pCt. 
He Brz, and by a line DF 
for the red erystals which 
runs from 127° to 0° and 
8.6 percent. HeBrs. (in 
molecules), 
The significance of these 
two lines is as follows. Be- 
low a temperature given by 
the line DE, mixed crystals 
Be Bes Mol.9, Hel, Of a certain concentration 
iB i must separate red mixed 
crystals belonging to the line DA. The compositions of the two 
change as the temperature falls, until, at a sufficiently low tempe- 
rature, homogeneous red crystals remain. 
Since the two lines lie somewhat far apart, even when a small 
