A Simple Gas Blowpipe.

—A simple form of gas blowpipe is shown in [Fig. 68], the rubber tube connecting it with the gas supply being fixed on the pipe at the point of connection with the cock. To construct the appliance, one end of a piece of brass gas pipe of the required length with, say, a ³⁄₈-in. bore, is bent as shown, whilst at the back of the curve thus made a hole is drilled to admit a tube A ⁵⁄₁₆ in. in diameter. This should have one end (see dotted lines) bent to correspond with the angle previously formed in the larger tube, whilst its other extremity should be bent upwards. Make these pipes red hot where they are to be bent, and, if they are afterwards plunged in cold water, the material will to some extent be softened, and its tendency to split will be obviated. The smaller tube is passed through the hole in the bend of the larger one, the ends being almost flush and quite concentric. Solder the parallel portions of the tubes together, and then fix a gas-regulating cock to the larger one, as in [Fig. 68]. The end is then connected to an ordinary bracket or burner by means of an indiarubber tube G, and a short piece of tubing is fitted with a bone or other mouthpiece, and attached to the projecting end of the air tube. This instrument will do any soldering, and will be suitable for melting gold, silver, and brass, or brazing odd jobs in iron or steel. Of course, when used for the last-named purpose it would be in conjunction with asbestos tubes or other supports.

Fig. 68.—Simple Form of Gas Blowpipe

Fig. 69.—Larger and more efficient Blowpipe