Using the blowpipe is not difficult.  The lips and cheeks should be puffed out with a mouthful of air, which is ample to blow a flame while the lungs are being refilled.  In this way, it is possible to use the blowpipe steadily, and not intermittently, as is necessary if the lungs alone are the “bellows.”

Small glass funnels, such as are used in many chemical operations, are made by first forming a bulb, then puncturing the bulb at the top, when hot, with a piece of charcoal, and smoothing down or flaring the edges.  Very small and fine glass tubes, such as are used in experiments to demonstrate capillary attraction, water or other liquid rising in them when they are plunged into it, are made by heating as long a section of tubing as can be handled in the flame—­2 in. will be found enough—­and, when very hot, giving the ends a sudden vigorous pull apart.  The tube pulls out and gets smaller and smaller as it does so, until at last it breaks.  But the fine thread of glass so made is really a tube, and not a rod, as might be supposed.  This can be demonstrated by blowing through it at a gas flame, or by immersing it in colored liquid.  The solution will be seen to rise some distance within the tube, the amount depending on the diameter of the tube.

The file is for cutting the glass tubing into lengths convenient to handle.  It should be a three-cornered file, of medium fineness, and is used simply to nick the glass at the place it is desired to cut it.  The two thumbs are then placed beneath the tube, one on each side of the nick, and the tube bent, as if it were plastic, at the same time pulling the hands apart.  The tube will break off squarely at the nick, without difficulty.

The entire outfit may be purchased from any dealer in chemical or physical apparatus, or any druggist will order it.  Enough tubing to last many days, the Bunsen burner, blowpipe, file and charcoal should not exceed $2 in cost.

** Cadmium and Solder [421]

The addition of cadmium to soft solder composed of tin and lead, lowers its melting point and increases its strength.

** Telegraph Codes [422]

[Illustration:  Telegraph Codes]

** How to Make a Cruising Catamaran [423]

A launch is much safer than a sailing boat, yet there is not the real sport to be derived from it as in sailing.  Herein is given a description of a sailing catamaran especially adapted for those who desire to sail and have a safe craft.  The main part of the craft is made from two boats or pontoons with watertight tops, bottoms and sides and fixed at a certain distance apart with a platform on top for the passengers.  Such a craft cannot be capsized easily, and, as the pontoons are watertight, it will weather almost any rough water.  If the craft is intended for rough waters, care must be taken to make the platform pliable yet stiff and as narrow as convenient to take care of the rocking movements.