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36 MODERN MAGIC LANTERNS.
met with was due to the rapid cooling of the ether by its
evaporation, which, since the lower the temperature the less
volatile the fluid, soon led to the oxygen passing over without
picking up sufficient vapour. The earlier patterns usually
ignored this difficulty, leaving the operator to warm the
saturator with hot water, a hot brick, or even a lamp, but
later patterns utilise the waste heat from the jet by enclosing
the saturator with the jet itself in the lantern.
The fact that the writer has had no experience with this
form of light is sufficient reason for not dealing with it here
Fig. 28. ARRANGEMENT FOR USING ETHER VAPOUR.
at any length ; but besides this, it is not a form of illumination
which any but skilled lanternists should attempt.
Quite apart from the safety or otherwise of the various
forms of saturator now readily obtainable, ether, an extremely
volatile fluid the vapour of which forms an
explosive mixture with air, in inexperienced hands may
be most dangerous, and is best left alone.
Coal gas by itself was occasionally used in the lantern,
being burnt in a ring or Argand burner, but its heating
power in this form is out of proportion to the light
SATURATORS, INCANDESCENT GAS BURNERS, ETC. 37
obtained, which can easily be surpassed by a petroleum
lamp, and we therefore merely allude to it.
Quite recently another illuminant employing coal gas
alone has been put forward, in the shape of the incandescent
or Welsbach light. In this a Bunsen or feebly luminous
but very hot flame, caused by burning gas which has
previously been mixed with air, is surrounded by a mantle
or gauze-like covering composed principally, we believe, of
zirconia. This at once becomes white hot and emits a
brilliant light, which, while not Etanding comparison, either
in intensity or concentration, with limelight, is still brilliant
enough for many purposes. The system has not, as far as
we know, been adopted in many lanterns, but it possesses
advantages in the shape of simplicity and economy which
may lead to its extended use in the future.