- Stored-Grain Pests. 47 
FUMIGATION. 
Carbon disulphid, carbon tetrachlorid, and hydrocyanic-acid gas 
are the fumigants in most common use to-day for treating infested 
grain. Of these, carbon disulphid is the best for treating grain in 
bulk. It is heavier than air and if applied at the top of a gas-tight 
bin of grain will penetrate down through the grain, killing the 
insects without injury to the grain, providing it is dry. It has the 
one great disadvantage of being inflammable and will explode if fire 
in any form is brought near it. It is in general use on farms for the 
protection of grain in cribs (see U. S. Department of Agriculture, 
Farmers’ Bulletins 799 and 1029.) 
Carbon tetrachlorid is not as effective as carbon disulphid and costs 
more. For these reasons it~is not in such general use. It has the 
great advantage of removing the fire hazard, as it is not inflammable 
and does not explode in presence or fire. 
Hydrocyanic-acid gas is not of value in fumigating bulks of grain. 
When grain is stored in sacks in warehouses, heavy doses of this gas 
will control grain pests. This method of fumigation is discussed in 
Department Bulletin 872. 
Fumigation with chloropicrin is not in general use at present. 
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