[Illustration: FIG. 19.--A siphon experiment.]
This tubing may be obtained from almost any druggist.
Prepare for your experiment by taking the length of tubing and, with a gas flame, drawing one end out to a point.
Having done this, bend the tube twice, as shown in Fig. 19, particular care being taken to avoid any sharp angles. The bending of this tubing is easily done by holding it in a gas or spirit-lamp flame until the flame is colored yellow. The glass is then soft enough to be gently bent to the required angle.
Over the end which is not pointed slip the piece of india-rubber tubing, and then place this end in the colored water.
By applying suction to the pointed end of the tube with your mouth, the siphon may be set in motion.
If now you so arrange the tube that the oval opening is partly out of water, the flowing liquid will draw in bubbles of air which, passing alternately down the tube with the drops of colored water, produce a very pretty result.
The shape and size of the air bubbles may be altered at any time by raising or lowering the tube, and this will add to the effect of the experiment.
The experiment may be again varied by removing the tube from the liquid, and before lowering it again, allowing 10 or 12 inches of air to enter. This long bubble will be seen to pass slowly down the tube until it arrives at the small opening, when it will be expelled at a great rate. The liquid following this bubble acquires the same velocity, and, arriving at the point, is ejected with such force that it will rise to a height of 6 or 7 feet.
Most of you would like to make an electric fountain, especially when you learn how simple and easily arranged is this striking experiment. Your apparatus consists solely of a glass, a long india-rubber tube, with two small glass tubes and a piece of sealing-wax (a stick of sulphur or piece of vulcanite will do just as well).
Make a small nozzle by drawing out a length of bent glass tubing, and, by means of a long piece of india-rubber piping, fix it to another piece of bent glass tubing. Place the first piece of tubing bent at two right angles over the side of a glass filled with water, taking care that the reservoir thus formed is from 3 to 4 feet above the nozzle (Fig. 20).