To bend a length of the tubing, let it be assumed for the purpose of making a syphon, it is only necessary to cork one end of the tube and heat it near the top of the Bunsen flame, turning the tubing constantly to make it heat evenly on all sides, until it is a dull red in color.  It will then bend of its own weight if held in one hand, but to allow it to do so is to make a flat place in the bend.  The heating should be continued until the red color is quite bright, when the open end of the tube is put in the mouth and a little pressure of air made in the tube by blowing.  At the same time, the tube is bent, steadily but gently.  The compressed air in the tube prevents it from collapsing during the process.

To make a bulb on the end of a tube, one end must be closed.  This is easily done by heating as before, and then pulling the tube apart as shown in Fig. 4.  The hot glass will draw, just like a piece of taffy, each end tapering to a point.  This point on one length is successively heated and pressed toward and into the tube, by means of a piece of charcoal, until the end is not only closed, but as thick as the rest of the tube, as in Fig. 5.  An inch or more is now heated white hot, the tube being turned continually to assure even heating and to prevent the hot end from bending down by its own weight.  When very hot, a sudden puff into the open end of the tube will expand the hot glass into a bulb, as in Fig. 6.  These can be made of considerable size, and, if not too thin, make very good flasks (Fig. 7) for physical experiments.  The base of the bulb should be flattened by setting it, still hot, on a flat piece of charcoal, so that it will stand alone.

To weld two lengths of, glass tubing together, heat the end of a tube and insert the point of a piece of charcoal in the opening, and twirl it about until the end of the tube has a considerable flare.  Do the same to the end of the other tube, which is to be joined to the first, and then, heating both to a dull red, let them touch and press lightly together as in Fig. 8.  As soon as they are well in contact, heat the two joined flares together, very hot, and, pulling slightly, the flares will flatten out and the tube be perfectly joined.  Tubes joined without previous flaring have a constricted diameter at the joint.

To make a T-joint in two pieces of tubing, it is necessary to make a hole in the side of one piece, as shown at A in Fig. 9.  This is accomplished by the aid of the principle of physics that gases expand when heated.  Both ends of the tube, which should be cold, are corked tightly.  The whole is then gradually warmed by being held near the flame.  When warm, a small flame is directed by the blowpipe from the Bunsen flame to a spot on one side of

[Illustration:  Glass Blowing and Forming]

the closed tube.  As it heats, the air within the tube expands and becomes compressed, and as soon as the hot spot on the side of the tube is soft enough, the confined air blows out, pushing the hot glass aside as it does so, leaving a small puncture.  This is to be enlarged with pointed charcoal until it also flares as shown at B. This flare is then connected to the flared end of a straight tube, C, and the T-joint, D, is complete.