32 CIRCULAR 6 3 5, U. S. DEPARTMENT OF AGRICULTURE 



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FlGUBB 22.— Rectangular steel chambers used in the fumigation of tobacco in vacuum, 

 each chamber being 37 by 6% by 4% feet and having a volume of 1,162 cubic feet. 

 These tanks were installed for treating imported cigarette tobacco and each has a 

 capacity of about 17,500 pounds of tobacco. 



DOSAGES AND EXPOSURE OF AVAILABLE FUMIGANTS 



The most widely used gases for the fumigation of tobacco in vacuum 

 are hydrocyanic acid and a mixture of 1 part of ethylene oxide and 9 

 parts of carbon dioxide. A mixture of 15 percent of methyl formate 

 and 85 percent of carbon dioxide has given good results in the fumiga- 

 tion in vacuum of bales of tobacco of low density. In bales closely 

 packed the results have been unsatisfactory with the methyl formate- 

 carbon dioxide mixture. 



The dosages and exposures recommended for the fumigation ot 

 tobacco in vacuum when the temperature of the tobacco is 70° F. Dr 

 above are given in table 1. 



Table 1. — Dosages of various gases recommended for the fumigation of different types 

 of tobacco in vacuum chambers at a temperature of 70° F. or above 



Fumiganl 



Dosage per 1,000 cubic feet 



Tobacco 



(Ciearette 



Hydrocyanic acid. ._ -Cigar filler 



[Cigar wrapper 



I Cigarette 

 ( ' liar wrapper." ..I— 

 .Manufactured cigars _ 



(Cigarette 



Methyl formate and carbon dioxide {Cigar filler 



[Manufactured cigars. 



