These alloys, when of a certain composition, have considerable strength and hardness. With an increase in the quantity of the iron the hardness increases, but the solidity is lessened. A copper and iron alloy of considerable strength, and at the same time very hard, is made of copper, 66 parts; iron, 34. These alloys acquire, on exposure to air, an ugly color inclining toward black, and are therefore not adapted for articles of art.
Copper Nickel.
Delta Metal.
| I | II | III | IV | V | |
|---|---|---|---|---|---|
| Copper | 55.94 | 55.80 | 55.82 | 54.22 | 58.65 |
| Zinc | 41.61 | 40.07 | 41.41 | 42.25 | 38.95 |
| Lead | 0.72 | 1.82 | 0.76 | 1.10 | 0.67 |
| Iron | 0.87 | 1.28 | 0.86 | 0.99 | 1.62 |
| Manganese | 0.81 | 0.96 | 1.38 | 1.09 | — |
| Nickel | traces. | traces. | 0.06 | 0.16 | 0.11 |
| Phosphorus | 0.013 | 0.011 | traces. | 0.02 | — |
I is cast, II hammered, III rolled, and IV hot-stamped metal. Delta metal is produced by heating zinc very strongly in crucibles (to about 1600° F.), and adding ferromanganese or “spiegeleisen,” producing an alloy of 95 per cent zinc and 5 per cent of iron. Copper and brass and a very small amount of copper phosphate are also added. {64}
Gong Metal.
Production Of Minargent.
Minofor.
| I | II | |
|---|---|---|
| Copper | 3.26 | 4 |
| Tin | 67.53 | 66 |
| Antimony | 17.00 | 20 |
| Zinc | 8.94 | 9 |
| Iron | — | 1 |
Minargent and Minofor are sometimes used in England for purposes in which the ordinary Britannia metal, 2 parts tin and 1 part antimony, might equally well be employed; the latter surpasses both of them in beauty of color, but they are, on the other hand, harder.