34 CIRCULAR 3 6 9, U. S. DEPARTMENT OF AGRICULTURE 



content, for they are likely to retain a disagreeable odor and taste 

 after fumigation. 



Ethylene diehloride can be purchased separately or already mixed 

 with carbon tetrachloride or trichloroethylene. 



ETHYLENE OXIDE 



Etlrylene oxide is a colorless gas at ordinary temperatures, but 

 below 50° F. it is a colorless liquid. It has a boiling point of about 

 57.2°, and therefore can be used with success at temperatures con- 

 siderably below 70°. 



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

 centrations up to 3% 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 measuring 

 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. 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%, 18%, 

 75, or 195 pounds. 



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 disulfide, chloropicrin. ethylene oxide, 

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

 provided it is suitable for treating the commodity stored in the 

 bin. Carbon disulfide should not be used unless the fire hazard can be 

 controlled. 



The fumigant should be sprinkled or sprayed 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. 



