CONTROL OF INSECTS IN TOBACCO 



25 



Figure 1 8 



An atmospheric chamber for fumigating tobacco, 

 refrigerator-type door closing against the gasket. 



Note the 



lion chamber should have a vent pipe, operated by readily accessible 

 valves, extending well above the roof of the building. A powerful 

 fan should be connected to this vent, so that gases from the chamber 

 may be quickly exhausted, and kept running when the fumigation 

 chamber is entered shortly after fumigation. 



Both hydrogen cyanide and a mixture of acrylonitrile and carbon 

 tetrachloride have given satisfactory results in atmospheric chambers. 

 Acrylonitrile-carbon tetrachloride may be poured into shallow pans 

 in the chamber. The operator should wear a suitable gas mask 

 while pouring. A superior method is to place a large, shallow 

 stainless-steel pan on a steam or hot-water coil near the ceiling of the 

 chamber and run a small pipe through the Avail or ceiling of the 

 chamber so that it will discharge into the pan. The outer end of the 

 pipe is connected with a funnel, held in a vertical position. The re- 

 quired dosage of f umigant is placed in a stainless-steel container, which 

 is then inverted into the funnel, and the liquid f umigant flows into the 

 pan by gravity. However, the liquid acrylonitrile-carbon tetra- 

 chloride mixture is flammable and care should be taken to avoid 

 exposure to spark or flame. At the dosages recommended the gas 

 is not explosive, but, like many other fumigants, it is both flammable 

 and explosive at high concentrations. Unnecessary electric or tele- 

 phone lines should therefore be disconnected before fumigation is 

 begun. A sparkproof and explosionproof electric fan should be 

 operated in the chamber to prevent stratification of the gas. 



Discoids impregnated with hydrogen cyanide may be used in at- 

 mospheric chambers, but are more dangerous to handle than the liquid 



