Experimental Glass Blowing FOR BOYS BY CARLETON J. LYNDE, PH. D. Professor of Physics MacDonald College, Quebec Province, Canada Prepared under the direction of ALFRED C. GILBERT YALE UNIVERSITY, 1909 EXPERIMENTAL GLASS BLOWING Boys, glass tubes are made in the sizes shown in Fig. 2, and in larger sizes. You will use sizes 2, 4, and 6 in the following =experiments=. Experiment 1. Fun bending glass. [Illustration: FIG. 2 SIZES OF GLASS TUBING ] Hold a piece of No. 2, with both hands, in the flame of the alcohol lamp, and turn it constantly (Fig. 3). Do you find that when the glass becomes nearly red hot, it becomes soft and bends easily? [Illustration: FIG. 3 HEATING GLASS TO SOFTEN IT ] Take the tube out of the flame, bend it into any shape you wish (Fig. 4), and allow it to cool. Do you find that the glass hardens when it cools and retains the bent shape? Heat the tube near the first bend, turn it constantly, take it out of the flame, and make another bend. Repeat this and make all kinds of fantastic shapes. Place all hot glass on the cooling blocks, not on the table. Glass is used in many, many ways by the human race; for example, to make bottles, tumblers, window glass, and so on, and all of these uses depend upon the facts which you have just illustrated, namely, that glass becomes soft when heated and hard when cooled again. [Illustration: FIG. 4 BENDING GLASS ] THE LAMP The wick should be cut straight across and should project above the wick holder about ⅛ inch (Fig. 5), or a little more if you require more heat. Burn wood alcohol or grain alcohol, because they give flames without soot or smoke. Fill the lamp to within a ½ inch of the top only; it will burn one hour. The hottest part of the flame is not down close to the wick, as most beginners suppose, but up just beneath the tip. [Illustration: FIG. 5 THE LAMP ] Buy your alcohol at a drug store in quantities of one pint or more. When you are through experimenting for the day pour the alcohol from the lamp back into the pint bottle and cork the bottle tightly. Alcohol left in the lamp gradually evaporates and is lost. Do not let the lamp stand with alcohol in it for any considerable time—overnight for example—because fuel alcohol contains water and when it evaporates from the wick, the alcohol evaporates first and leaves the water in the wick. Then when you try to light the wick again, you will find that you cannot do so, because, of course, water does not burn. If this happens to you, take the wick out, dry it, and start the lamp again. [Illustration: FIG. 6 MAKING A SCRATCH ]