(159) 
which join each other at an angle at 217,°2. Although all the mixed 
erystals are rhembohedral, the series of mixtures is discontinuous ; 
at 217°2 there is a sudden transition from mixed erystals with 
38 0/, (in molecules) NaNO, (£) to those with 26 °/, (D). The fused 
mass which is in equilibrium with both contains 19.5°/, (in mole- 
cules) of Na NO, (C). 
On cooling the following transformation takes place at 217°, 
Fused mass C + crystals “= crystals D. 
Ay NO, 
Mol. |, 
Na NO, 
This temperature possesses all 
the characteristics of a transition 
temperature. 
The points on the lines ZB 
and 4D represent the compositions 
of the mixed crystals which are 
deposited from a liquid having 
the composition represented by 
points on the lines CB and AC 
corresponding to the same tem- 
perature. 
Below AD a series of homo- 
geneous mixed crystals containing 
from 0 to 26°/, Na NO; exists, 
and below ZB a similar series 
from 38—100 °/, Na NOs. 
The mixed erystals containing 
26 and 38°/, which coexist at 217°, 
gradually change in composition 
as the temperature falls, in such 
a way that the limits between 
which no mixture exists become 
more widely separated, so that 
at 138° they are 4.2 and about 
50 °/,. NaNO; (H and J). The 
region within which homogeneous 
mixed crystals exist, becomes 
smaller and smaller. 
Below 160° a change occurs in 
the series which is rich in silver, 
in consequence of which the 
rhombohedral erystals are con- 
verted into rhombic erystals. 
With pure silver nitrate this takes 
12° 
Proceedings Royal Acad. Amsterdam. Vol. II. 
