320 Hydrocyanic Acid Gas Against Household Insects 



should be removed from the room. When everything is ready the 

 operator should drop the bag of cyan i '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 downward 

 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. 



