pa BULLETIN 186, U. S. DEPARTMENT OF AGRICULTURE. 
FUMIGATION CHAMBER. i 
The fumigation chamber (fig. 1 and fig. 2, 6) is of iron tubing, 36_ 
inches long by 12 inches in diameter. One end of this cylinder is per- i 
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, b),— 
which is held in place by clamps. One face of the plate is ground to 
fit the flange, which is also ground. A wide rubber gasket is placed 
between the two faces when the plate is clamped in position. The 
chamber is designed to lhe with its longest axis in a horizontal position. 
On. the side of the chamber intended to he uppermost three openings | 
are made, one being in the center and one at each end. The opening — 
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Fic. 1.—Diagram of fumigation chamber: a, Iron cap; b, brass plate clamped on end of chamber; ¢, gas 
cock for attaching suction hose; d, vacuum gauge; ¢, 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, d), while a tubula- 
ture is placed in the opening near the flange. The tubulature is 
closed with a perforated rubber stopper bearing a dropping funnel 
(fig. 1, €) so arranged that the bulb and stopcock are outside the 
chamber, while the tube extends down inside the chamber nearly to 
the bottom. The rubber stopper and dropping funnel 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 equivalent of about 0.05 of a millimeter of mer- 
cury, is used to secure an almost complete vacuum (fig. 2, @). 
