Fig. 92c. the glass blowing arrangement ready to use
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.
How to Blow a Bulb.
—Take a good piece of glass tube about ³⁄₄ inch in diameter and 15 inches long; draw one end out long and thin for about 3 inches as shown at [A in Fig. 93].
