Ring Gold.—Six dwts. 12 grs. pure copper, 3 dwts. 16 gra. fine silver, and 1 oz. 5 dwts. pure gold. Jeweller's gold is made of variable proportions of pure gold and copper, and sometimes of silver.
Imitation of Silver.—One lb. copper, and I oz. tin. This alloy will be of a deeper colour than silver, but in other respects it is very similar.
Alloy of Platinum with Steel.—Platinum although the most infusible of metals, when in contact with steel melts at a comparatively low temperature, and combines with it in any proportion. This alloy does not rust or tarnish by exposure to a moist atmosphere, for many months. The alloy is malleable, and is well adapted for instruments which would be injured by slight oxidation, as mirrors for dentists, &c. The best proportions do not yet appear to be known ; but it appears that if much platinum be used, the alloy has a damask or wavy appearance. Steel for cutting instruments is much improved by even of platinum.
Alloy of Silver and Steel.—Steel 500 parts, and silver 1 part. If a large proportion of silver is employed, the compound appears to be a mechanical mixture only. The silver is distinctly seen in fibres mixed with the steel, and
the alloy is subject to voltaic action. When the proportion does not exceed „„-I the compound appears to be a chemical union ; the steel is rendered much harder, forges remarkably well, and is infinitely superior to the best cast steel for cutting instruments, &c.
Alloy of Steel with Rhodium.—If from 1 to 2 per cent. of rhodium be com bined with steel, the alloy possesses great hardness, with sufficient tenacity to prevent cracking, either in forging or hardening. This alloy requires to be heated about 730 Fehr. above the best English cast steel in tempering. It is superior to that metal; but the scarcity of rhodium will prevent the extensive use of this valuable compound.
Fusible Alloys.—Four oz. bismuth, 2* oz. lead, and 1 oz. tin. Melt the lead first, and then add the other metals. This alloy will melt in boiling water, although the melting temperature of the several components is much higher ; via. lead, 612°; bismuth, 476°; tin, 442°.