The Louisiana Democrat. [volume] (Alexandria, La.) 1845-1918, 1886-02-03
ELECTRIC LIGHTS.
How the Bamboo, Glass and Platinum of
Electric Lamps Are Prepared.

How the Bamboo, Glass and Platinum of
Electric Lamps Are Prepared.
The incandescent electric light has be-
come familiar object to every one.
The little glass bulbs with their brilliant
horseshoe of glowing iilament attract no
more attention than the Pickering gas
jet. But the facts about the gas jet are
easily and generally understood, while
the electric lamp is still a puzzle to
many people. Both produce light by
incAndescence. The molecules of gas
are rendered incandescent by the heat
generated by the combustion of other
molecules. The blue portion of every
gas flame is where combustion
is taking place, and from that
comes the heat which keeps the
rest in Il state of incandescence. With
the electric lamp it is the heat produced
by the friction of an electric current
compelled to 60 through fine carbon
tilament, which raises that tilament to a
condition Of incandescence and pro-
duces light.
The three substances which enter into
the composition of an electric lamp are
glass, platinum wire and bamboo or pa
per. Glass bulbs are readily prepared
by the usual methods of glass blowing,
but the preparation of the bamboo is a
delicate piece of work In the best
lamps the little horseshoe is made of
bamboo and this material has proved its
superiority to its rival, paper, in several
ways. The bamboo comes from Japan
in bundles of slips foot in length.
japanese bamboo is OF finer quality than
the Chinese. 1t is first split up into
little square strips. Girls round these
off by running them through dies until
they look like little broom straws. These
are put in crucibles with graphite and
submitted to white heat for several
hours. This carbonizes them thorough
ly. The filaments are not all of exactly
the same size when taken out of the cru
cibles, and if used in that state would
present varying resistances to the cur
rent and the lamps would not be even
and economical in their working. To
make them uniform they are put one
by one into a glass jar from which the
air can be exhausted and hydrocar-
bon gas--the lightest of the products of
pelrolcum-can be admitted. A current
of electricity is run through the horse
shoe iiiament and it absorbs carbon
from the gas until the operator sees
that its resistance has betAl reduced to
the regulation amount The standard
used i'll the factory from which this de-
scrjption was obtained is two hundred
and fifty ohms. The moment when the
resistance has reached the desired point
is told by means of an apparatus ia
miliar to electricans-the Wheatstone
brid ge.
Now, the lamp is in three parts; the
bulb, the carbon tilament and the stop
per containing the two platinum wires
which are to connect the horseshoe of
carbon with the system of wires that
carries the current all over a building to
the hundreds of lamps. 1t only remains
to put the stopper in its place at the
larger end of the pear-shaped glass
bulb, seal 1t air-tght in the flame of a
blow-pipe, extract the air from the bulb
by a mercury pump and then seal the
other end. The bulb is made of the
thinnest glass and before the air is ex-
hausted from it will break easily. After
the vacuum is created, however, it can
be handled carelessly without injury;
and when it does break there is a report