CHEMICAL CHANGES IN CALCIUM ARSENATE. oF 
Fie. 52.—Effect of container on water-soluble arsenic oxid. 
SUMMARY. 
Commercial calcium arsenate in the dry powdered form manufac- 
tured for insecticidal purposes absorbs carbon dioxid slowly from 
the atmosphere during storage and increases in water-soluble arsenic- 
oxid content, unless it is packed in containers that are practically 
air-tight. The rates of these changes show a close relationship and 
depend largely upon the type of container in which the material is 
packed. 
The absorption of carbon dioxid is the first change noted. This 
is followed a little later by a rise in the water-soluble arsenic oxid 
