| Mn. per cent. | C. | Si. | S. | P. | ||
|---|---|---|---|---|---|---|
| A | 18 to 20 | 2 to 3 | 10 to 12 | Traces scarcely perceptible. | About 0.100. | Extra Quality for soft metals. |
| B | 15 to 18 | 3.00 | 10 to 8 | Medium Quality. | ||
| C | 15 to 10 | 3.25 | 8 to 6 | |||
| D | 5 to 10 | 3.50 | 4 to 6 | Ordinary for hard metals. |
The first alloys of manganese and copper were made in 1848, by Von Gersdorff; soon after Prof. Schrötter of Vienna made compounds containing 18 or 20 per cent. of manganese by reducing in a crucible the oxides of copper and manganese mixed with wood charcoal and exposing to a high heat.
These alloys were quite ductile, very hard, very tenacious, and capable of receiving a beautiful polish; their color varies from white to rose color, according to the respective proportions of the two bodies; they are particularly interesting on account of the results which were obtained by adding them to certain metallic fusions.
It is well known that in the fining of copper by oxidation there is left in the fined metal the suboxide of copper, which must then be removed by the refining process, using carbon to reduce the copper to its metallic state. M. Manhès, taking advantage of the greater affinity of manganese for oxygen, found that if this last element was introduced into the bath of copper during the operation of refining, the copper suboxide would be reduced and the copper obtained in its metallic condition. For this purpose during these last years real cupro-manganese has been prepared, occupying the same position to copper as the spiegel or the ferro-manganese does toward the manufacture of steel. M. Manhès used these same alloys for the fusion of bronze and brass, and recommended the following proportions:
| 3 | to | 4 | kilog. of | cupro-manganese | for 100 kilog. of | bronze. |
| 0.250 | to | 1 | do. | do. | do. | brass. |
| 0.150 | to | 1.2 | do. | do. | do. | copper. |
In every case the alloy is introduced at the moment of pouring, as is the case in the Bessemer or Martin process, taking care to cover the fusion with charcoal in order to prevent the contact with air, together with the use of some kind of a flux to aid in the scorification of the manganese.
According to M. Manhès a slight proportion of manganese added to bronze appears to increase its resistance and its ductility, as is shown in the following table, provided, however, that these different alloys have been subjected to the same operations from a physical point of view; that is, pouring, rolling, etc.
| Cu. | Sn. | Mn. | Weight of fracture. | Elongation | ||
|---|---|---|---|---|---|---|
| Ordinary Bronze | 90 | 10 | 20 kil. | 4.00 | ||
| Bronze with Manganese, | A, | 90 | 10 | 0.5 | 24 kil. | 15.00 |
| Do. | B, | 90 | 10 | 1.0 | 26 kil. | 20.00 |
The White Brass Co., of London, exhibited at Paris, in 1878, manganese bronzes of four grades of durability, destined for different uses and corresponding to about 20 to 25 kilos of the limit of elasticity, and 36 to 37 kilos of resistance to fracture; the number 0 is equivalent after rolling to a resistance to fracture of 46.5 kilos, and 20 to 25 per cent. of elongation.
Such results show beyond contradiction the great interest there is in economically producing alloys of copper, manganese, tin, zinc, etc. In addition, they may be added to metallic fusions, for deoxidizing and also to communicate to the commercial alloys (such as bronze, brass, etc.) the greatest degree of resistance and tenacity.