oe ee 
eee ee ee 
Hare’s Blowpipe. 301. 
D, a conical brass screw plug, inserted into a hole in the 
cask, to be removed or reinserted, as may be convenient. 
E a plug of wood for closing the pipe B. F a cock for 
regulating the escape of gas. The plug D being removed, 
and zine in pieces introduced by the hole so as to cover the 
false bottom, diluted acid is to be poured into the cask, till 
the lower apartment becomes full. The cock F being 
closed, the hydrogen produced by the chemical action soon 
expels so much of the acid from the lower compartment of 
the cask, as to depress it below the zinc, when the action 
stops, till the expenditure of the gas allows the acid again to 
reach the metal. The plug E is of use to prevent the acid 
from pressing on the gas below, when pressure is not want- 
ed. Fig. 7 may be understood by its analogy with Fig 6, 
(Fig. 8? Ed.) being merely another mode of putting the 
same principle into operation. Casks of the form of Fig. 
6, (Fig. 8? Ed.) may be used as oxygen gas holders. The 
lower apartment is to be filled with water, the cock closed, 
and the plugs E, D put into their places so as to be quite 
tight. The pipe G only is to be open, and through this, the 
end of a tube is to be introduced, proceeding from a vessel 
in which oxygen may be generated. The gas displaces the 
water, which, as it flows out is to be caught and poured in- 
to the upper apartment of the cask. When the lower apart- 
ment becomes full Gis to be closed. It is then only neces- 
sary to remove the plug E, in ordei to allow the water to 
press upon the gas, and propel it, when requisite, through a 
tube to the blowpipe. ios 
Fig. 11 represents a contrivance, by which any vessel, 
with but one orifice, as a bottle, a demijohn, or carboy, 
may be made to act as an air holder; so that a number 
may be filled with oxygen gas over a preumatic cistern, may 
be laid by, and then used as wanted. The cylinder A is to 
be inserted in the place of the cork or stopple. This cylin- 
der has two perforations nearly collateral, one not more 
than one quarter of the diameter of the other. The smaller 
one, B, communicates with a small tube, furnished with a 
