MAKING A SPIRIT LEVEL ] Make a spirit level as follows: Take a piece of No. 4 tube about 7 inches long, heat a space about 3 inches long in the lamp flame, turn constantly, and when soft remove from the flame, hold both ends and allow the center to sink into a slight curve (1, Fig. 65). Let the tube cool, mark the center of the curve with ink, and make marks 2 inches from the center on each side. Hold the tube crosswise in the lamp flame, heat at one mark, draw down the tube and close it (2). In a similar manner draw down the tube at the other mark but do not close it (3). Let the tube cool and fill it with alcohol to the level shown in 4. To do this easily make the pipette (5), suck alcohol into it within about 1 inch of the top, put your finger over the top, insert the lower end of the pipette to the bottom of 4, and remove your finger. [Illustration: FIG. 66 MOUNTING THE SPIRIT LEVEL ] Heat the small part of 4, without heating the alcohol, and close the tube (6). Now attach the level to a smooth board as 2 or 3, Fig. 66, mark the center of the bubble, and your spirit level is ready for use. Experiment 47. To make a fountain-pen filler. Attach a rubber coupling to the large end of one of your No. 4 nozzles, close the other end of the coupling with a glass plug, and your fountain-pen filler is made (Fig. 67). To make the plug, close one end of a piece of No. 4 tubing, allow it to cool, cut off to a length of 1 inch and smooth the rough edges. Insert the closed end of this plug into the rubber coupling. Practice using the filler by drawing up and shooting out water. [Illustration: FIG. 67 A FOUNTAIN-PEN FILLER ] Experiment 48. To make a syringe. Take a half length of No. 6 tube and smooth both ends in the lamp flame or blowpipe flame. Now to make a plunger: Cut an 8½-inch length of No. 2. smooth one end, close the other end and blow a slight bulb. When cold, wet the closed end and insert it into a small wet rubber coupling. =Note=: Always grasp a tube near the end when you insert it into a coupling or stopper, because if you hold it too far back you may break it. Insert it with a twisting motion, after wetting the end and the inside of the coupling or stopper. [Illustration: FIG. 68 A SYRINGE ] Wet the inside of the large tube, wet the plunger and rub it on a cake of soap to make it slippery, then try it in the large tube. If the plunger is too large, stretch the coupling lengthwise; if it is too small, crowd the coupling together lengthwise. If the bulb is too large or too small, dry it, heat in the blowpipe flame until it shrinks, and blow another. When the plunger is made, attach a No. 4 nozzle to the No. 6 tube with a large coupling, arrange as in Fig. 68, and your syringe is made. Fill the large tube with water and see how long a stream you can make. [Illustration: FIG. 69 ANOTHER SYRINGE ] Experiment 49. To make another syringe.