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. Manhes 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.

--------------------------+-----+-----+------+---------

-+------------+
|     |     |      |  Weight  |            |
| Cu. | Sn. |  Mn. |   of     | Elongation |
|     |     |      | fracture |            |
--------------------------+-----+-----+------+----------+---

---------+
Ordinary Bronze           | 90  | 10  |      | 20 kil.  |    4.00    |
Bronze with Manganese, A, | 90  | 10  |  0.5 | 24  "    |   15.00    |
Do.    do.          B, | 90  | 10  |  1.0 | 26  "    |   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.

While many investigators have tried to form alloys of copper and manganese by combining them in the metallic state (that is to say, by the simultaneous reduction of their oxides), the Hensler Bros., of Dillenburg, have found it best to first prepare the metallic manganese and then to alloy it in proper proportions with other metals.  Their method consisted of reducing the pure pyrolusite in large plumbago crucibles, in the presence of carbon and an extra basic flux; the operation was carried on in a strong coke fire, and at the end of about six hours the crude manganese is poured out, having the following composition: 

Manganese          90   to 92
Carbon              6   to  6.5
Iron                0.5 to  1.5
Silicon             0.5 to  1.2

By refining, the manganese can be brought up to 94 to 95 per cent. of purity.  It is from this casting of pure manganese that is obtained the substance used as a base for the alloys.  This metal is white, crystalline, when exposed to the damp air slowly oxidizes, and readily combines with copper to form the cupro-manganese of the variety having the composition—­