=Open-flame Gas Burners.=--Gas jets of the open-flame type continue to be used to some extent but the more efficient mantle lamp has very largely supplanted lights of this kind. In the past, these gas lights were made in a great many styles and were known under a variety of trade names--the fish-tail burner, the bats-wing burner and the Argand burner--and were at times very generally used for gas lighting. [Illustration: 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. [Illustration: 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.