THE TOBACCO BEETLE. 57 



PREPARATIONS FOR FUMIGATION. 



The fumigating closet or box should be perfectly tight to prevent 

 escape of gas. In fumigating storage rooms or warehouses all open- 

 ings should be closed and the windows and doors arranged so that 

 they may be opened from the outside when the building is aired. 

 Do not enter the room, until it is thoroughly aired. The cubic con- 

 tents of the closet, room, or box to be fumigated should be deter- 

 mined, so that the exact quantity of the different chemicals needed 

 may be known. Food supplies that may be stored in the building 

 should be removed, as moist foods, such as meats and vegetables or 

 fruit, may absorb or retain the gas. 



Care must be taken in fumigating large warehouses in close prox- 

 imity to dwellings, as the liberation of a vast quantity of hydro- 

 cyanic-acid gas may endanger the persons within. 



For generators use stoneware or crockery jars. They should be 

 sufficiently deep that the liquid will not boil over when the gas is 

 generated. 



Hydrocyanic-acid gas is lighter than air. For this reason place 

 the generator underneath the material to he fumigated or on the floor 

 of the room. Whenever the room or building is of large size it is 

 advisable to use two or more generators, limiting the amount of cya- 

 nid to 2 or 3 pounds in any one generating jar. The jars should be 

 of small diameter in order that the cyanid may be completely cov- 

 ered by the acid and water. 



PROCESS OF FUMIGATION. 



The chemicals used in generating hydrocyanic-acid gas are placed 

 in the generating jar in the following order: First, water; then sul- 

 phuric acid; last, just before closing the fumigating closet or build- 

 ing, the cyanid. Measure into the generating jar the proper amount 

 of water, then add the acid slowly in the proper amount. Consider- 

 able heat will be developed by the addition of the acid, and for this 

 reason it is best not to mix the water and acid until just before the 

 cyanid is put in, as the heated liquid will act more quickly on the 

 cyanid. The water and acid should be mixed as directed above. Do not 

 pour water into acid. Severe burns may result from the ebullition 

 or sputtering of the liquids if the order of mixing the water and acid 

 is reversed. The acid should be kept in glass-stoppered bottles. 

 Cyanid should be kept tightly sealed, as it deteriorates rapidly when 

 exposed to the air. For convenience the cyanid may be put into 

 thin paper sacks and these dropped into the generating jar. This 

 method is applicable if large dosages are Used ; if only a small quan- 

 tity of the cyanid is required, however, it is not best to use a paper 

 wrapper, as the generation of the gas is somewhat retarded. An 



