The _manganese bronze_, which we have previously referred to, and which is used by the White Brass Company of London, is an alloy of copper, with from one to ten per cent. of manganese; the highest qualities of resistance, ductility, tenacity, and durability are obtained with one to four per cent. of manganese, while with twelve per cent. the metal becomes too weak for industrial uses. +-----------+---------+-----------+-------------+------------+ | Manganese | | | Weight of | | | bronze. | Copper.| Manganese.| fracture in | Elongation.| | | | | kilos per | | | | | | square mm. | | +-----------+---------+-----------+-------------+------------+ | A | 96.00 | 4.00 | 19.00 | 14.60 | | B | 95.00 | 5.00 | 20.62 | 10.00 | | C | 94.00 | 6.00 | 20.80 | 14.60 | | D | 90.00 | 10.00 | 16.56 | 5.00 | +-----------+---------+-----------+-------------+------------+ The preceding table gives some of the experimental results obtained with the testing machine at Friedrich-Wilhelmshuette on the crude cast ingots; the resistance is increased, as with copper, by rolling or hammering. The _manganese German silver_ consists of Copper................ 70.00 Manganese............. 15.00 Zinc.................. 15.00 But as this alloy often breaks in rolling, the preference is given to the following proportions: Copper................ 80.00 Manganese............. 15.00 Zinc.................. 5.00 This results in a white, ductile metal, which is easily worked and susceptible of receiving a beautiful polish, like the alloys of nickel, which it may in time completely replace. The _bronzes of manganese, tin, and zinc_ were perhaps the first upon which important investigations were made; they were obtained by adding to an alloy of copper, zinc, and tin (ordinary bronze) a definite quantity of the cupro-manganese of the type indicated above (Cu 70, Mn 30). By this means the resistance is increased fully nine per cent., probably in the same way as the copper, that is, by the deoxidizing effect of the manganese, as both the copper and the tin are always more or less oxidized in ordinary bronzes. Manganese combines with tin just the same as it does with copper, and the proportion which is recommended as giving the highest resistances is three to six per cent. of cupro-manganese. However, notwithstanding the use of cupro-manganese, the tin, as in ordinary bronzes, has a tendency to liquate in those portions of the mould which are the hottest, and which become solid the last, especially in the case of moulds having a great width. From a series of experiments made at Isabelle Huette, it has been found that the metal which has the greatest resisting qualities was obtained from