MILLS AND OTHER BUILDINGS 167 



house during the process of fumigation. It has re- 

 cently been applied in a room of the Division of 

 Botany, United States Department of Agriculture, by 

 W. R. Beattie, for the destruction of cockroaches. He 

 recommends the use of the gas at the rate of o.io to 

 0.22 gramme cyanide per cubic foot for the destruc- 

 tion of flies, cockroaches, moths, etc. For fleas and 

 bedbugs the writer has found that a dose varying from 

 0.20 to 0.22 gramme cyanide per cubic foot is far more 

 desirable. 



This method will be found very useful in clearing 

 large hotels, dwelling-houses and other buildings used 

 as summer resorts of undesirable pests. The gas 

 should be applied at a time when the buildings are 

 not occupied. On account of its very rapid diffusion, 

 from three to twenty-four hours will accomplish the 

 desired results. No fumigation for less than three 

 hours is recommended for household pests. Under no 

 circumstances should it be used in a house or other 

 building occupied by other individuals, either above, 

 below, or on either side of the room or apartment 

 fumigated. The gas will in no way injure any article 

 of furniture found in the ordinary household, Care 

 should be taken, however, to remove all edible mate- 

 rials. Water used for drinking should not be left in 

 the room. The gas should not be handled by persons 

 who are not thoroughly familiar with its deadly na- 

 ture. It is, therefore, not generally recommended for 

 use in houses unless applied by an expert. 



Explosive properties. In all our experiments and 

 recommendations we have kept the amount of potas- 

 sium cyanide considerably below the danger limit, so 



