INDUSTRIAL FUMIGATION AGAINST INSECTS 33 



The concentrated vapor of ethylene oxide is inflammable, but con- 

 centrations up to 3!/2 pounds per 1,000 cubic feet of space are non- 

 explosive and noninflammable. 



A dosage of 2 pounds per 1,000 cubic feet will give satisfactory 

 results in a tight vault, with an exposure of from 10 to 20 hours. 

 The liquid, which is sold in cylinders, can be drawn off into a measur- 

 ing container and poured into the evaporating pan of the vault. 

 Owing to its extreme volatility, it should not be drawn from the 

 cylinder until the fumigation chamber is ready for the charge. 



Ethylene oxide gas is not injurious to fumigated commodities, 

 and no obnoxious odor or poisonous residue is left upon them. The 

 gas is not highly toxic to man and can be handled in small quan- 

 tities without danger or discomfort. Nevertheless, the operator 

 should avoid breathing the fumes for any length of time and should 

 not enter a heavy concentration without wearing a gas mask. 



If ethylene oxide is used alone, it is advisable not to operate an 

 electric fan inside the vault, lest an inflammable concentration of 

 the gas has been accidentally obtained. 



Ethylene oxide can be purchased in cylinders containing 3%, 18y 2 , 

 75, or 195 pounds. In the two largest containers this fumigant costs 

 42 cents a pound, f. o. b. the factory. When delivered from ware- 

 houses, the price is 46 cents a pound east, and 48 cents west, of the 

 Rocky Mountains, f . o. b. warehouses. 



BIN FUMIGATION 



Bins used for the storage of foodstuffs, yarn, hosiery, etc., fre- 

 quently need to be fumigated. For this purpose any of the heavier- 

 than-air gases, such as carbon disulphide, chloropicrin, ethylene 

 oxide, or ethylene dichloride-carbon tetrachloride mixture, can be 

 used, provided it is suitable for treating the commodity stored in the 

 bin. 



The fumigant should be sprinkled evenly over the surface of the 

 contents of the bin, and the bin should then be covered as tightly 

 as possible. As the fumigant evaporates, the vapor, being heavier 

 than air, gradually penetrates the material from the top to the 

 bottom. 



The quantity of fumigant needed will depend upon the tightness 

 of construction of _the bin, the type of material to be fumigated, and 

 the fumigant being used. Bins are seldom so tight as fumigation 

 vaults ; hence larger dosages are necessary. 



Since it is difficult to obtain uniform penetration of fumigants 

 beyond certain depths in bins, it is often desirable to apply the 

 fumigant in separate portions as the bins are filled. 



VACUUM FUMIGATION 



In vacuum fumigation commodities are placed in a gastight steel 

 chamber, and a large proportion of the air is removed and replaced 

 with a gas lethal to insects. By this method immediate penetration 

 of commodities by the gas is obtained and the susceptibility of the 

 insects is increased by the reduction of the oxygen content of the 

 chamber. This permits smaller dosages and shorter exposures than 



