726 Proceedings of Royal Society of Edinburgh. [sess. 
Crystals from 
Mixture. 
Percentage of Ammonia. 
Mean. 
(1) 
(2) 
1 
•04 
•04 
2 
*71 
•68 
•70 
3 
•89 
•87 
•88 
4 
1-23 
1-20 
1-22 
5 
3-31 
3-33 
332 
The results obtained by plotting the specific volume against the 
percentage of ammonia are shown in the diagram. 
It will be seen that the density of the pure potassium compound 
appears to be too high. No explanation can be at present offered 
for this deviation. . The concordant results in the case of the four 
PERCENTAGE of AMMONIA. 
mixtures give considerable support to the application of Retgers’ 
hypothesis to the chromoxalates, and to the view that the potassium- 
ammonium salts of these series are merely mechanical mixtures, 
and not chemically definite compounds. No doubt similar experi- 
ments with the red series of chromoxalates would give corresponding 
results. 
