A gas cock,
H, is soldered onto tank A, as shown, from which the gas may be
taken through a rubber tube. Fill tank B with water and set tank A
into it. This will cause some air to be enclosed, which can be
released by leaving the cock open until tank A settles down to the
point where the water will begin to run in the perforations of the
little tank. The water then comes in contact with the carbide and
forms gas, which expands and stops the lowering of tank A. Then
the cock must be closed and tubing attached. It is dangerous to
attempt to strike a match to light a jet or the end of the cock
while air is escaping and just as the first gas is being made.
Wait until the tank is well raised up before doing this.
--Contributed by James E. Noble, Toronto, Ont.
** Homemade Annunciator [57]
When one electric bell is operated from two push-buttons it is
impossible to tell which of the two push-buttons is being operated
unless an annunciator or similar device is used. A very simple
annunciator for indicating two numbers can be made from a small
box, Fig. 1, with an electric-bell magnet, A, fastened in the
bottom.
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