SHOP EQUIPMENT 



483 



12. Blast lamp, (Fig. ."571, $4.50) ami foot bellows (Fig. ."..lii, .+.1.1)0) or 

 compressed air and tubing. These are mainly used for soldering (or 

 brazing) and are exceedingly useful. If no gas supply is available an 

 alcohol lamp (20 cents) and a small mouth blowpipe (20 cents) may be 

 used for soldering many small articles. 



13. Solder and soldering acid. Solder is best obtained in the form of a 

 heavy coiled wire about 1/8 inch in diameter (string solder). This form 

 is especially adapted for soldering with a blast lamp (which is by far 

 the best method for this kind of work). Soldering acid is made by put- 



Fig. 372. Details of the mechanical construction of the adjustable tambour shown in 

 Fig. 14. One-half natural size. It is recommended that all laboratories which have suffi- 

 cient shop facilities make up at least a few such tambours as this for recording special 

 results where large volume changes in the tambour are required. Upper picture, seen from 

 above; middle picture, seen from the side; the two lower pictures, the smallest and largest 

 tambour bowls. All parts made of brass. Thin sheet aluminum writing points are used. 

 These may be cut on a hard board from thin sheet aluminum with a penknife and a metal 

 ruler. 



ting about 2 or 3 ounces of hydrochloric acid in a 6 or 8 ounce wide- 

 mouthed bottle and dropping in more granulated zinc than the acid can 

 dissolve. The bottle is placed in a hood so long as fumes are given off 

 from the mixture. A glass tube (S or 10 inches long) is placed in the 

 bottle to be used as a pipette for placing the acid on the articles to be 

 soldered. 



