To Blow a Bulb on the End of a Tube

For blowing bulbs on tubes, for flasks and the like, you need a regular glassblower's blow-pipe in order to get a hotter flame than a Bunsen burner gives.

Fig. 92B. Cross Section Of A Home Made Blow-Pipe

You can buy a blow-pipe as shown at A in Fig. 92 for $1.50,96 or you can easily make one as follows : get a brass tube 3/4 inch in diameter and 10 inches long and drill a 1/2 inch hole in it 3 inches from one end; fit another pipe of the same size and length at an angle of about 30 degrees to the first one; put a stopcock in the latter pipe and solder it to the first pipe over the hole as shown at B in Fig. 92.

96 Blowpipes and bellows can be bought of Hammacher, Schlemmer and Co., Fourth Ave. and 13th St., New York.

Fig. 92C. The Glass Blowing Arrangement Ready To Use

Next take a glass tube 1/4 inch in diameter and 14 inches long and make a bend in it 3 inches from one end. Make a hole through a cork and push it over the glass tube; slip the tube into the brass pipe and force the cork into the end of the latter tight enough to hold the glass tube exactly in the middle of it.

Connect the lower end of the glass tube with a rubber tube about 3 inches long to a brass tube of the same size and 8 inches long and fit a stopcock into this pipe. This completes the burner but you want to set the lower ends of the two tubes into and through the top of your table so that the stopcocks are above it and the lower ends of the tubes project below the table.

Next connect the large brass tube with a gas jet or other source of illuminating gas and the small brass tube with a foot blower or other source of compressed air as shown at C. The blower can be an ordinary molders' bellows which you can buy for about $1.50, or you can make a pair, or you can buy a regular blowpipe bellows as shown at D, which are very much better, for about $8.00.

Fig. 92D. A Regular Foot Bellows

By adjusting the mouth of the glass tube - which is the air tube - that is, drawing it in and out of the mouth of the brass tube which is the gas tube, and by regulating the amount of air and gas, a pointed flame or a brush flame, that is, a flame of large size, can be had at the mouth of the blowpipe according to the work you are doing.