Untitled

32 MODERN MAGIC LANTERNS.
Pressure gauges and regulators are often screwed together
and used as one fitting, as shown in Fig. 26, a very convenient
method. If no regulator or other fitting is used on the
cylinder, a nipple will be required to which to attach the
tube (Fig. 27). Rubber tubes are
best simply slipped over the metal
tubes to connect them, and not tied
in any way, but to do this they
must be a good fit, that is, not too
loose. If tied, and from any cause
the pressure becomes excessive,
they will burst, whereas if only
slipped on they will simply be
blown off.
Fig. 27. NIPPLE.
Fig. 26. COMBINED REGULATOR AND GAUGE.
The rubber tubing should be
fairly stout, so as not to be likely
to form "kinks," and should not be of the cheapest quality.
A very good kind can be obtained at about sixpence per
COMPRESSED GASES. 33
foot, red or black. Latterly a piping formed by convolutions
of a corrugated iron strip has been put upon the
market, which, where the gas has to be led any distance, is
excellent. It can be got in any length, with unions fitted
to its ends, at very little if anything more than the cost
of good rubber tube, and if one or two of the audience
chance to stand on it, it does not collapse at once and put
the light out, as rubber would. The rubber tube formed on
an iron wire spiral is best avoided.
Coal gas if kept in a cylinder any length of time greatly
deteriorates, attacking the steel and forming with it a viscous
liquid known as iron carbonyl. The presence of this in the
gas is manifested by a rapid blackening or reddening of the
lime which lessens the illumination, and by a blocking up of
the nipple of the jet. The amount of iron taken by this means
from the substance of the bottle is not sufficient to materially
weaken it, but the compound is annoying in the way abut e
indicated, and clogs up the cylinder valve.
The railway companies having thrown difficulties in the
way of the carriage of cylinders of compressed gas, since one
or two recent accidents, the stipulations which the Midland
Company make for this service are given, as typical of the
nature of such regulations generally. The sender has to sign a
form stating that he certifies "that the consignment complies
with the conditions that the cylinder or cylinders must
be of wrought iron, or of mild steel of the best quality, containing
not more than 0.25 per cent. of carbon, thoroughly
annealed after manufacture, of sufficient strength, and
efficiently tested." This should be stipulated when purchasing
the cylinder, upon the seller of which should be
thrown the responsibility of supplying an article with such
a guarantee. The company also require that the cylinder
shall be securely protected by being
Encased in closely plaited hemp or coir ; or
fixed in ordinary wooden box without lid, but with
rope handle ; or
loose in ordinary wooden box, with lid secured by
strap ; or
efficiently protected by closely-woven wickerwork, the
valve of the cylinder not to project beyond the wickerwork.