In making hydrogen, bottle B is partly filled
with zinc nodules formed by slowly pouring melted zinc into water.
Hydrochloric acid is then poured in the small funnel, thus partly
filling bottles A and C. When the acid rising from C comes in
contact with the zinc, hydrogen gas is generated and fills bottle
B. The gas continues to generate until the pressure is sufficient
to force the acid back down the tube into bottle C, when the
action ceases. As fast as the gas is used the acid rises in the
tube and generates more, thus keeping the pressure nearly
constant, the pressure depending on the difference between the
levels of the acid in bottle A and bottle B. As this device is
easily upset, a ring-stand should be used to prevent its being
broken, or if it is to be a permanent apparatus it may be mounted
on a substantial wooden base. This apparatus may also be used for
preparing acetylene gas or almost any gas which requires a mixture
of a solid and liquid in its preparation.
--Contributed by C. S. J., Detroit.
** Restoring Tone to a Cracked Bell [71]
Many a bell with a deadened tone due to a cracked rim, can be
given its original clear ringing sound by sawing out the crack
with a common hacksaw.
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