. A manual of mechanical dentistry and metallurgy . rfaces together until perfect coaptation is required size and shape of the mold is then cut out inone section of the block; the two pieces are then secured inplace by binding with wire, or with the use of clamps. Asbestos Molds.^—Comparatively inexpensive, and at thesame time more convenient and (lural)le contrivances de-signed for the same puri)ose. combining both crucible and GOLD. 209 ninld. and eni1)raciiTi^- the s])ecial advantages claimed forcharcoal, may he ohtained at the dental depots. One of thesimplest forms of this kin
. A manual of mechanical dentistry and metallurgy . rfaces together until perfect coaptation is required size and shape of the mold is then cut out inone section of the block; the two pieces are then secured inplace by binding with wire, or with the use of clamps. Asbestos Molds.^—Comparatively inexpensive, and at thesame time more convenient and (lural)le contrivances de-signed for the same puri)ose. combining both crucible and GOLD. 209 ninld. and eni1)raciiTi^- the s])ecial advantages claimed forcharcoal, may he ohtained at the dental depots. One of thesimplest forms of this kind is the asbestos melting and ingotblock shown in Fig. 175. Wdien in use, place a piece ofcharcoal over the bowl-shaped portion of the ingot block,as it facilitates heating the metal. The small asbestos slabbeing placed in position to complete the mold, and retainedin place by clamping, the metal, when sufficiently fused, ispoured into the mold by tipping the block. The bowl orcrucible has a thin coating of whiting, to prevent borax or Fig. 175-. other flux from adhering. Should this occur, however, ruba little moist whiting in the bowl. The sides of the blockare encased in strips of wood, to protect the hands fromheat. Carbon Molds.—A very ingenious, convenient, and usefulaf)paratus, combining crucible and ingot-mold, by the use ofwhich ingots of gold, silver, etc., may be quickly obtainedwithout the use of a furnace, is shown in Fig. 176. Thecrucible is of molded 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
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Keywords: ., bookcentury1900, bookdecade1900, bookidman, booksubjectmetallurgy
