i 
fumigation, as the cost of shutting down, cleaning machinery, etc., 
would destroy the profit. In this latter fumigation, 54 pounds 
cyanid of potash were used, equivalent to 13.9 ounces to 1,000 cubic 
feet, or about one-third more than necessary if the building was tight 
and the ingredients known to be pure. 
SUMMARY OF VALUE OF THE HYDROCYANIC-ACID GAS METHOD. 
The special qualities of hydrocyanic-acid gas and some of the ad- 
vantages which it possesses over other insecticides (as well as its 
disadvantages) as a fumigant for mills and other buildings infested 
by insects may be briefly summarized as follows: 
1. It is generated without the aid of fire, in which respect there 
is a distinct advantage in its use in preference to sulphur fumiga- 
tion, unless the Clayton process is employed. 
2: It is practically noninflammable and nonexplosive in a large 
confined space when generated according to methods now in practice. 
3. It is possible, therefore, to use this method of fumigation where 
with the employment of either bisulphid of carbon or sulphur a con- 
flict with insurance companies might occur. 
4. It is not injurious to cereals or other dried products in storage, 
either for food or for seed, in which respect it is superior to sulphur, 
which destroys the germinating qualities of seeds as well as plant 
life generally. 
5. Fumigation may be employed at any time, night or day, but 
preferably in a moderately warm temperature and on a calm day 
without wind. 
6. In a very short time after ventilation of the treated premises 
the characteristic ‘‘peach-pit’’ odor of the gas entirely disappears 
and, properly used, no solid residue remains in the generator. 
7. Hydrocyanic-acid gas is lighter than air and has considerable 
penetrating power—not so great, however, as possessed by sulphur 
where forced into buildings and other inclosures by means of the 
Clayton process. 
8. The gas, generated in air-tight inclosures, creates a positively 
deadly atmosphere, and thus used destroys most stages of the flour 
moth and some other insects. It is still more deadly at a much 
shorter exposure to man and other mammals, including domestic 
animals, rats, mice, and other vermin, than to mill insects. 
9. It is the most powerful poison in common use, which fact being 
fully recognized, human beings are not readily tempted to run unnec- 
essary risks of exposure to its deadly fumes. 
10. The process is comparatively inexpensive under conditions 
which permit of buildings being made nearly gastight, especially 
when a complete exposure of between 24 and 36 hours can be 
obtained. 
Cir. 112] 
