THE POTATO-TUBER MOTH. 5 
tight. In the case of bisulphid of carbon there is great danger in 
bringing the chemical into proximity to fire, such as a lighted lantern 
or cigar, for the gas is highly inflammable and even explosive. Then, 
too, the bisulphid-of-carbon method costs slightly more than the 
hydrocyanic-acid-gas method. 
Fumigation with hydrocyanic-acid gas, properly performed, is 
not dangerous, but if improperly performed is decidedly dangerous 
to human and other animal life, as the fumes are very poisonous and 
are deadly when inhaled in any amount. This gas is more pene- 
trating than bisulphid of carbon and can be used by an intelligent 
person without trouble, if he first familiarizes himself thoroughly 
with the procedure by carefully studying the printed directions or 
assisting some one who has had experience in this work. The cubic 
contents of the receptacle to be fumigated, on which is based the 
amount of chemicals to be used, can be readily computed. 
THE CONSTRUCTION OF A FUMIGATOR. 
A building, box, or room (see fig. 3) of about 100 to 200 bushels’ 
capacity suitable for the fumigation of a quantity of potatoes would 
contain about 500 cubic feet. A fumigator of this cubic capacity 
might be built 8 feet square by 8 feet in height. A good, and perhaps 
the best, means of preventing the escape of the gas would be to line 
the fumigator with sheet tin, with soldered joints, and over sheathing. 
Another method would be to sheath the room inside, cover the walls, 
ceiling, and floor with tarred or heavy building paper, with joints 
well lapped, and cover the inside with matched ceiling boards. The 
fumigator should always be equipped with a tight door in which the 
joints have been broken, similar to the door of a refrigerator or safe, 
-and should close with two refrigerator catches against a thick felt 
weather strip, which should render it aoe eal gas-tight. Thus 
constructed it would furnish sufficient space for the fumigation of 
about 200 bushels of material. There would also be sufficient space 
for the application and diffusion of the hydrocyanic-acid gas,* carbon 
bisulphid, or other fumigant from the top with a charge more than 
necessary for the quantity of potatoes treated. 
Approved: 
JAMES WILSON, 
Secretary of Agriculture. 
rad ASHINGTON, D. C., September 30, 1912. 
Note.—Fumigation with hydrocyanic-acid gas is considered in Circular No. 112, which will be sent to 
anyone who requests it, stating that it is to be used for the potato-tuber moth. 
O 
