32 CIRCULAR 369, U. S. DEPT. OF AGRICULTURE 



vault. The vapors of carbon tetrachloride have an anesthetic effect 

 when breathed by man. Although they are not quickly toxic, it is 

 not safe to remain for any length of time in a strong concentration of 

 the gas. 



The cost of carbon tetrachloride ranges from about 5.8 cents per 

 pound in large quantities to 10 cents per pound in small lots. 



ETHYLENE DICHLORIDE 



Ethylene dichloride is a colorless liquid with an odor similar to 

 that of chloroform. It has a boiling point of 183.2° F., and on ex- 

 posure to air it evaporates. The mixture of air with ethylene di- 

 chloride vapor is 1.2552 times as heavy as air at the same temperature 

 and pressure (77° F., 29.9 inches). 



It is an effective fumigant in gastight vaults, but owing to its 

 high boiling point it should be used at a temperature of at least 70° 

 F. and preferably somewhat higher. 



The vapors of ethylene dichloride are slightly inflammable. It is 

 therefore customary to use this fumigant in combination with some 

 noninflammable chemical, such as carbon tetrachloride or trichloro- 

 ethylene. A mixture of 3 volumes of ethylene dichloride with 1 vol- 

 ume of carbon tetrachloride or trichloroethylene is free from fire 

 hazard under ordinar}^ conditions, and is an effective fumigant when 

 used at the rate of 14 pounds per 1,000 cubic feet of space, unless the 

 vault is filled with absorbent material, when a heavier dosage is 

 required. 



This fumigant is applied by pouring it or forcing it under pres- 

 sure into the evaporating pan of the vault. A small fan blowing 

 on the surface of the liquid insures a more rapid vaporization of the 

 fumigant and hastens its killing action. 



The vapors of ethylene dichloride have an anesthetic effect upon 

 man, and although it is safe to use in small quantities, one should 

 not be exposed to a heavy concentration of the gas for more than a 

 very brief period without a gas mask. 



The mixture of ethylene dichloride and carbon tetrachloride or 

 trichloroethylene has no corrosive action on metals or any bleaching 

 or staining action on textiles of any sort. It is suitable for treat- 

 ing grains and seed, but should not be used for foodstuffs with a 

 high fat content, for they are likely to retain a disagreeable odor 

 and taste after fumigation. 



Ethylene dichloride can be purchased separately or already mixed 

 with carbon tetrachloride or trichloroethylene. 



The mixture of 75-percent ethylene dichloride and 25-percent car- 

 bon tetrachloride is priced at 6.44 cents a pound in nonreturnable 

 55-gallon drums which contain 590 pounds net, f. o. b. the factory, 

 with freight allowance to destinations east of the Rocky Mountains. 

 The corresponding price west of the Rocky Mountains is 6.94 cents 

 a pound. In smaller quantities the price is higher. 



ETHYLENE OXIDE 



Ethylene 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 it can be used with success at temperatures con- 

 siderably below 70°. 



