154 FUMIGATION METHODS 



in connection with hycjrocyanic acid gas in buildings 

 and other enclosures. On one occasion the writer had 

 a large quantity of grain badly infested with insects 

 stored in an old building. The wheat was confined 

 in several large rooms more or less open. Carbon 

 bisulphide was used liberally for the destruction of the 

 insects in the grain, but it was found that a large 

 number of the creatures in the upper part of the build- 

 ing escaped, owing to the openness of the enclosure. 

 The building was made as tight as possible by hang- 

 ing blankets, fertilizer bags, etc. , over the cracks, and 

 a charge of hydrocyanic acid gas was liberated. 

 Double the quantity ordinarily recommended for a 

 tight enclosure was used. The experiment was largely 

 successful, and the insects were thoroughly destroyed 

 both in the grain and throughout the building. It is 

 not desirable, however, to generate the tw r o gases at 

 the same time. In this instance the hydrocyanic acid 

 gas was applied forty-eight hours after the carbon 

 bisulphide was used. 



The strongest arguments in favor of hydrocyanic 

 acid gas are: (i) it is generated without fire; (2) it is 

 comparatively cheap; (3) non-inflammable and non- 

 explosive when generated with normal amounts; (4) 

 does not injure grain or manufactured products, 

 machinery, furniture, or equipment of any kind; (5) 

 leaves no odor or residue after fumigation; (6) is 

 lighter than air, and quickly permeates all cracks and 

 crevices in which pests hide; (7) can be used at night 

 or in the daytime at pleasure; (8) creates a death 

 atmosphere in which no animal can live, including rats, 

 mice, and other vermin; (9) its very deadly nature 



