Fig. 193.—Swing-bracket gas lamp with open-flame burner.
The common gas jet is illustrated in Fig. 193. The figure shows a bracket fixture which is generally fastened to a pipe in the wall. A swing-joint at A permits the flame F to be moved into different positions. The annular opening A permits the gas to pass to the jet in any position to which the light is moved. The gas-cock C is a cone-shaped plug, which has been ground to perfectly fit its socket. It should move with perfect freedom, and yet prevent the escape of the gas. A slotted screw N permits the joint to be readjusted, should the plug become loose in the socket.
The gas-tips T are made of a number of different kinds of materials and are commonly termed lava-tips but tips for gas and gasoline are frequently made of metal. The bottom of the tip is cone-shaped, which permits it to be forced into place in the end of the tube with a pair of pliers. In size the tips are graded by the amount of gas which they will allow to escape in cubic feet per hour. For example—a 4-foot tip will use approximately 4 cubic feet of gas per hour. They are made in a number of sizes to suit the varying requirements.
The Inverted-mantle Gasoline Lamp.
—The inverted-mantle gasoline-gas lamp shown in Fig. 194, furnishes a good example of mechanism and principle of operation, when used with the hollow-wire system. This is the bracket style of lamp but the same mechanism is used in other forms of fixtures. Lamps of similar construction are suspended from the ceiling, either singly or in clusters; they are also used in portable form.
Fig. 194.—Sectional view of hollow-wire mantle gasoline lamp.
In Fig. 194 the lamp consists of a bracket H, which is secured to the wall and through the stem of which the gasoline is conducted to the generator by the pipe W. The arrows show the course of the gasoline and its vapor as it passes through the lamp. On entering the generator the gasoline first passes, the percolation, through an asbestos wick B, the object of which is to prevent the vapor pressure from acting directly on the gasoline in the supply tube. The gasoline passes through the wick B, largely by capillary action, as it must enter the generator against a pressure greater than that afforded by the pressure tank. The vaporization of the gasoline takes place in the tube above the mantle T, from the flame of which it receives the necessary heat.
In lighting the lamp an asbestos torch saturated with alcohol is ignited and hung on the frame, so that the flame may heat the generating casting N. This process usually requires less than a minute, generally about 40 or 50 seconds. The torch supplies heat sufficient to generate the vapor for lighting the lamp, but as soon as lighted the heat from the glowing mantle keeps the generator at the required temperature for continuous supply of vapor.
When the generator is sufficiently heated by the generating torch, the needle valve N is opened by pulling the chain P. This allows the gasoline vapor from the generating tube to escape at G into the induction tube R. As the vapor enters the induction tube at a high velocity, it carries with it the atmospheric air in quantity sufficient to render it completely combustible. The opening G and the tube together form a Bunsen burner. The lamp is so proportioned as to give a mixture of gasoline vapor and air that will produce complete combustion in the mantle T. The portion of the burner Z, through which the gas enters the mantle, is a brass tip, filled with a fluted strip of German silver, so arranged that the gas on entering the mantle will be uniformly distributed and that the heat generated will render the entire mantle uniformly brilliant.