Hold a piece of No. 2 tubing in the lamp flame and turn it constantly. When it is red hot and soft, take it out of the flame and pull your hands apart until the tube is stretched ten or twelve inches (Fig. 16). Is the tube in the shape shown in Fig. 17?
Fig. 16. Drawing A Thin Tube
A Glass Tube Stretched
Allow the tube to cool, break the large ends away from the thin tube, place one end of the thin tube in a glass of water, and blow into the other end to make air bubbles in the water (Fig. 18). If you can do so, it is a real tube. Does the thin tube bend easily and does it spring back when released?
Repeat the experiment with another piece of No. 2 tubing, but make the thin tube as long as you can.
Can you blow air through the thin tube, and does it bend very easily indeed?
Repeat with a piece of No. 4 tubing.
These thin hairlike tubes are called "capillary" tubes, from the Latin word capillus, meaning a hair.