2 BUl.LETIX im, U. S. DEPARTMENT OF AGRICULTURE. 



FUMIGATION CHAMBER. 



The fumigation chamber (fig. ] and fig. 2, b) is of iron tubing, 36 

 inches long by 12 inches in diameter. One end of this cyhnder is per- 

 manently closed with a heavy iron cap (fig. 1, a). The other end is 

 fitted with a flange and can be closed with a brass plate (fig. 1, h), 

 which is held in place by clamps. One face of the plate is ground to 

 fit the flange, wdiich is also ground. A ^vide rubber gasket is placed 

 between the two faces when the plate is clamped in position. The 

 chamber is designed to lie with its longest axis in a horizontal position. 

 On the side of the chamber intended to lie uppermost three Of)enings 

 are made, one being in the center and one at each end. The opening 



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Fig. 1. — Diagram of fumigation chamber: o, Iron cap; 6, brass plate clamped on end of chamber; c. gas 

 cock for attaching suction hose; d, vacuum gattge; f , dropping funnel, by means of which the sulphuric 

 acid is introduced into the chamber; /. beaker to contain cyanid. 



near the capped end is fitted with a gas cock (fig. 1, c), so that the 

 suction hose of a vacuum pump can be readily attached. A vacuum 

 gauge, registering the decrease in pressure in units equivalent to inches 

 of mercury, is placed in the center opening (fig. 1, cZ), while a tubula- 

 ture is placed in the opening near the flange. The tubulature is 

 closed mth a perforated rubber stopper bearing a dropping funnel 

 (fig. 1, e) so arranged that the bulb and stopcock are outside the 

 chamber, w^hile the tube extends dowm inside the chamber nearly to 

 the bottom. The rubber stopper and dropping fuimel can be readily 

 removed when seeds or other material to be fumigated are placed in the 

 chamber. An air pump, driven by a motor and capable of reducing 

 the air pressure to the eciuivalent of about 0.05 of a millimeter of mer- 

 cury, is used to secure an almost complete vacuum (fig. 2, a). 



