INDUSTRIAL FUMIGATION AGAINST INSECTS 



13 



stance, which for fumigation purposes is prepared in egg-shaped 

 lumps weighing approximately y 2 or 1 ounce each. It is a violent 

 stomach poison, and can also cause serious poisoning by being ab- 

 sorbed through open cuts on the hands. For this reason it is best 

 handled with a scoop or shovel. The hands should always be 

 protected. 



Figure 13. — Crock for the generation of hydrocyanic acid gas by the pot method, 

 set in a galvanized-iron tub to prevent injury to the floor in case the crock 

 cracks. 



Pure sulfuric acid is a heavy, colorless liquid, but the commercial 

 acid used in large-scale fumigation work is slightly colored, or 

 murky, owing to impurities. It is highly corrosive and will cause 

 injury if it is spattered on the clothing or body of the operator or 

 upon the floor. Sulfuric acid can be purchased in 11-gallon car- 

 boys or in smaller quantities in glass bottles. Glass bottles containing 

 the acid should be packed in a wooden box or paper carton to prevent 

 breakage. When large quantities of acid are required, a tilting frame 



