154 FUMIGATION METHODS 
in connection with hydrocyanic 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 two 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: (1) 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 
