320 Hydrocyanic Acid Gas Against Household Insects 
should be removed from the room. When everything is ready the 
operator should drop the bag of cyam'd gently into the jar, holding 
his breath, and should walk quickly out of the room. The steam¬ 
like gas does not rise immediately under these conditions, and ample 
time is given for the operator to walk out and shut the door. If 
preferred, however, the paper bag may be suspended by a string 
passing through a screw eye in the ceiling and then through the key¬ 
hole of the door. In this case the bag may be lowered from the out¬ 
side after the operator has left the room and closed the door. 
The writer has most often started the fumigation toward evening 
and left it going all night, opening the doors in the morning. The 
work can be done, however, at any time during the day and should 
extend over a period of five or six hours at least. It is said that bet¬ 
ter results will be obtained in a temperature of 70° F., or above, than 
at a lower degree. 
At the close of the operation the windows and doors may be opened 
from the outside. In the course of two or three hours the gas should 
be dissipated enough to allow a person to enter the room without 
danger. The odor of the gas is like that of peach kernels and is easily 
recognized. The room should not be occupied until the odor has 
disappeared. 
Fumigating a Large House 
The fumigation of a large house is merely a repetition, in each room 
and hall, of the operations already described for a single room. All 
the rooms should be made tight, and the proper quantities of water 
and sulfuric acid should be measured and poured into jars placed 
in each room with the cyanid in bags besides the jars. When all 
is ready, the operator should go to the top floor and work doivnward 
because the gas is lighter than air and tends to rise. 
Precautions 
The cyanid should be broken up into small pieces not larger than 
small eggs. This can best be done on a cement or brick pavement. 
It would be advantageous to wear gloves in order to protect the hands, 
although the writer has broken many pounds of cyanid without any 
protection on the hands. Wash the hands thoroughly at frequent 
intervals in order to remove the cyanid. 
The operations of the work must be carried out according to 
directions. 
