. A manual of mechanical dentistry and metallurgy . carbon, and is supported in positionby an iron side-plate. A clamp holds crucible and ingot-mold in position, swiveling on a cast-iron stand. The metal to be melted is placed in the crucible, and the flame of the blowpipe directed on it until it is perfectly fused. The waste heat serves to make the ingot-mold hot, and the whole is tilted over by means of the upright handle at the18 2IO MECHANICAL DENTISTRY AND METALLURGY, back of the mold. With this simple-instrument, a soundingot may be obtained at any time in a very few minutes. Aside from
. A manual of mechanical dentistry and metallurgy . carbon, and is supported in positionby an iron side-plate. A clamp holds crucible and ingot-mold in position, swiveling on a cast-iron stand. The metal to be melted is placed in the crucible, and the flame of the blowpipe directed on it until it is perfectly fused. The waste heat serves to make the ingot-mold hot, and the whole is tilted over by means of the upright handle at the18 2IO MECHANICAL DENTISTRY AND METALLURGY, back of the mold. With this simple-instrument, a soundingot may be obtained at any time in a very few minutes. Aside from the greater convenience and cleanliness, ascompared with the older method in which draft-furnace heatis used, there is great economy of time in the use of the last-named appliance combining crucible and mold, since aningot may be thus obtained, with the use of the bellowsblowpipe, in from two to three minutes. It is suitable formelting from two to four ounces of gold or silver. It not infrequently happens that, at the first pouring, the Fig. metals arrange themselves in the ingot in accordance withthe density of the several components, those of greaterspecific gravity passing to the bottom, and the lighter metalsremaining above. Whenever this occurs, the ingot must bebroken into pieces and remelted; this should be repeated, ifnecessary, until the alloy assumes a perfectly homogeneousappearance. It should then be annealed in hot ashes, whichsoftens the gold and removes the adhering grease. Forging.—Before laminating, the ingot should be reducedsomewhat in thickness by placing it on an even-faced anvilor other equally smooth and resistant surface, and subjecting GOLD. 21 I it to repeated blows with a heavy hammer. Tt should befrequently annealed, and the process of forging continued,alternately hammering and annealing, until the ingot isreduced one-half or more in thickness. Laminating or Rolling.—The reduced ingot, well an-nealed, is next rolled or spread out into a sh
Size: 2065px × 1210px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookidman, booksubjectmetallurgy
