The Arizona sentinel., 1886-02-06
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 a familiar object to every one. The little glass bulbs with their brilliant horseshoe of glowing ilament attract no more attention than the fiickering 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 state of incandescence. With the electric lamp it is tbe heat produced by the friction of anr electric current compelled to 20 through fine carbon flament, which raises that filament 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 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. It 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 a hydrocar- bon gas-the lightest of tie products of petroleum-can be admitted A current of electricity is run through the horse shoe filament and it absorbs carbon from the gas until the operator sees that its resistance has been reduced to the regulation amount The standard used in the factory from which this de- scription 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 fa- miliar to electricians-the Wheatstone bridge.
 Now, the lamp is in three parts; the bulb, the carbon filament 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 building to the hundreds of lamps. It only remains to put the stopper in its place at the larger end of the pear-shaped glass bulb, seaI It air-tight in the flame of a blow-pipe, extract the air from the bulb by 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 vacnum is created, however, it can be handled carelessly without injury; and when it does break there is report like that of a dozen pop-guns.
 The lamps are expected to burn six