Page:Popular Science Monthly Volume 91.djvu/638

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Clip for Carrying Pipe in the Vest Pocket Safely

A GREAT number of pipe users adhere to the straight stem for reasons known to the habitual smoker. However, carrying such a pipe is somewhat difficult.

��Popular Science Monthly

���A clip similar to the one used on a fountain pen for holding pipe in the vest pocket

If carried in the hip pocket it is liable to be broken, and if in the vest pockets it is liable to be dropped out and lost. For the worker who likes to and can have a frequent draw, it is most readily carried in one of the upper vest pockets. The illustration shows an easily made aluminum or brass clip that is bent to fit the stem of the pipe and which will securely fasten the pipe to the edge of the pocket. The idea was conceived after the writer had lost a few broken-in good ones, himself. — F. W. Bentley.

��A Silvering Process for Glass Instru- ments and Mirrors

DISSOLVE 2.5 grams of silver nitrate in 100 c.c. of distilled water, and add ammonia until the precipitate just goes into solution. Make up the solution to 250 c.c. When this has been done, prepare another solution containing .5 gram of Rochelle salt in 250 c.c. of water; boil the solution to dissolve the salt more rapidly. Keep both solutions in tightly stoppered bottles in the dark when not in use.

The surface to be silvered must be thoroughly cleaned by washing first with

��a strong alkali solution, then with dilute nitric acid, and finally with distilled water. After each washing, the surface should be rubbed with moist cheesecloth. A solu- tion of stannous chloride in water to which a few drops of hydrochloric acid have been added is then poured gently and evenly over the surface, which should then be well washed in tap water. Care should be taken not to touch the prepared surface with the fingers after the treatment with tin chloride.

While still wet the object is placed in a waxed dish or waxed paper, and a mixture of equal volumes of the two solutions already prepared quickly poured over it, avoiding splashing and air-bubbles. In about an hour the silvering will be com- plete; the liquid may be poured off, and the article dried. The silvered surface should never be touched by the fingers.

The best shellac for such a surface is prepared by dissolving 5 parts by weight of gutta-percha; 20 parts by weight of gum damar in 75 parts by weight of benzene. If these articles are not readily obtainable, the surface may be varnished with a very dilute shellac varnish. By this process anyone can easily construct hygrometers, mirrors, reflectors, and many other kinds of useful apparatus.

��Holding the T-Square on the Drawing- Board

WHEN using a small drawing-board not supported by a stand or other regular holding arrangement, the most convenient position in which to hold it while seated is to tilt it against the edge of the table. As a result, the T-square must be dropped to the base after each time it is used. The il- lustration shows how a simple attach- ment for the board and square can be made and applied which will hold the square at all times in place on the face of the board. A number of very small screweyes, two light rubber bands, and a piece of light but strong cord are all the materials needed. It is easily pushed up and down as required, and does not interfere with the placing or withdrawal of work.

���A cord on T-square head to hold it on board

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