Modern sheet-metal workers' instructor; practical geometry, mensuration, properties of metals and alloys ...

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 Excerpt: ...and rubbed over the inside of the vessel with a wad of salammoniac. When all parts are coated the superfluous tin is poured off, and the inside wiped smoothly with a wisp of tow held in a gloved hand in the case of an open vessel, or wrapped round a wire if the vessel has a narrow mouth. Washing in clean water follows to remove any salammoniac remaining, and the article is dried in sawdust. Finally, the inside is polished with a rag and whiting, and the outside with a rag and crocus. In hard soldering, or brazing, the parts to be united have to be raised to so high a temperature that the copper-bit is of no use, but the heat of a coke or charcoal fire, or in some eases of the air-blast, is employed. Moreover, since the work takes some time to execute, and because it is raised to so high a temperature, it is usual to secure the parts with soft iron wire, called binding wire. The flux used is borax, a compound which dissolves almost all oxides and earthy impurities that are likely to form on the joint. The hard or spelter solders mostly contain zinc, and the eye partly judges of the completion of the joint by the blue flame which accompanies the volatilization of the zinc. The spelter is granulated, and the borax is pounded fine. The two are mixed, and applied together, or separately, and sprinkled or spread along the joint. The heat is applied very gradually in order that the ebullition or boiling up of the borax, due to driving off of its water of crystallization by the heat, shall not displace the spelter from the joint. Afterwards the heat is increased, and at a low red the borax fuses, and at a bright red the solder fuses, and runs quickly into the joint. After covering or charging a joint with borax first and spelter afterwards, the water in the borax i...