. The principles and practice of dental surgery. It may be necessary sometimes to make gold wire for spiralsprings or other purposes; also hollow-tube wire. A draw-plate Fig. 186. (Fig. 186), strong pliers and bench-vise (Fig. 187) are all thatare necessary for this purpose. The draw-plate should be of thehardest steel, and the holes diminishing very gradually. Thepliers should be rough at the end for grasping the wire, whichmust be often annealed during the process. The simplest metiiod of winding wire into a spiral spring isto secure it betAveen two blocks of wood, held betAveen the jawsof a
. The principles and practice of dental surgery. It may be necessary sometimes to make gold wire for spiralsprings or other purposes; also hollow-tube wire. A draw-plate Fig. 186. (Fig. 186), strong pliers and bench-vise (Fig. 187) are all thatare necessary for this purpose. The draw-plate should be of thehardest steel, and the holes diminishing very gradually. Thepliers should be rough at the end for grasping the wire, whichmust be often annealed during the process. The simplest metiiod of winding wire into a spiral spring isto secure it betAveen two blocks of wood, held betAveen the jawsof a small bench-vise, as shown in Fig. 187. The upper endof the wire is then grasped by a hand-vise or sliding-tongs, inconnection with a spindle or steel wire, the size of a small knit- GOLD SOLDER. 641 ting-needle, six or eight inches in length. The spindle, restingon the blocks of wood, is made to revolve, and by this move- FiG. nient the gold wire is drawn through the blocks and wound firmlyand closely round the steel rod. GOLD SOLDER. In making gold solder, the metals employed for the purpose,if not pure, should be refined separately. Unless this is done,it will be difficult, and often impossible, to ascertain their rela-tive purity, which should be known to insure the desired gold is placed in a clean crucible with a little borax, and assoon as it has become perfectly melted, the silver, and after-ward the copper, are added. When all are melted, the alloymay be immediately poured into an ingot-mould, previouslywarmed and oiled. The process of hammering and rolling thesolder is the same as that described for gold-plate. In conse-quence of the large amount of alloy in solder, it is sometimes sostiff, and even brittle, as tb be with great difificulty rolled. Thisdifficulty is increased by the fact that its low fusibility makes itnot very easy to anneal it without melting. This is sehlom thecase wit
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