—To close one end of a tube, or seal it off as it is called, heat it in a fish-tail burner just as I explained for bending glass.
When the glass begins to get soft pull the two ends of the tube apart until the walls of the tube are drawn together as shown at [A in Fig. 89]. Cut a nick in the thin solid part with a file and break it off. If you want a closed end as shown at [B] heat the end of the tube you have sealed off and press it down on a piece of iron.
Fig. 89. sealing off the end of a tube
Fig. 90. how to make a hole in a tube
To Make a Glass Nozzle.
—In setting up chemical apparatus it very often happens that a glass nozzle is needed. To make a nozzle seal off a piece of glass tube as described above and by nicking it with a file you can have the hole in the end of the tube any size you want it.
To Make a Hole in a Tube.
—To make a hole of any size in a tube, or piercing it, as it is called, you ought to have a sharp pointed flame and a blow-pipe, which is [described] farther on.