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containing from 0 to 48 mol. percent of AgNO; or from 52 to 
100 mol. percent of AgNOs;: either the pure salts are deposited 
or else their mixed crystals. 
The fact that mixtures with a high percentage of either Ag NO; 
or TINO; are not quite solidified until close upon 80° proves that 
there can be only a very slight mixing in the solid phases. 
It is however, impossible to separate the crystals from the melt 
sufficiently completely to make it possible to decide, by means of 
an analysis of the separated crystals, whether a small intermixture 
occurs or not. | 
This may be more accurately found out by determining the 
transition points of the separated crystals. 
At the AgNO, — side, the rhombohedric crystals (whether 
consisting of pure AgNO; or mixed crystals) which are deposited 
from the melt at a high temperature, will change into the rhombic 
form when they are left in contact with the melt at a lower 
temperature; this change is accompanied by a retardation in the 
fall of the temperature. When the melt deposits pure Ag NOs th 
change takes place at 159°, but in the case of mixed crystals the 
temperature must be either higher or lower than 159°. 
The same is true of the crystals which deposite on the ‘I'l NO; 
— side. On observing the course of the solidification the retardation 
always occurred at 152° in the case of mixtures at the AgNO; 
side, which solidified about 160° and consequently contained from 
100 to about 80 percent at Ag NO,. 
At the TINO, side it always occurred at 142°. 
From this it follows that mixed crystals are not deposited on 
either side, or, at most, mixed crystals containing a very small 
admixture. . 
4. The solidified mixtures of different concentrations are, therefore, 
conglomerates of the doublesalt with AgNO; or Tl NOs. 
These, on a further decrease in temperature, undergo another 
change. When the mixtures are allowed to solidify on a glass slide 
and then exposed to a low temperature they gradually become 
opaque as may be noticed with the naked eye. ‘he temperature at 
which the transformation takes place cannot be determined by optical 
or thermometric methode as the change proceeds too slowly, and 
therefore, the dilatometrie process was applied. 
First of all, a comparative experiment was made to demonstrate 
that the change in the conglomerates is a change in the double 
salt and not of AgNO; or T1NOs alone. 
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