380 REPORT—1883. 
or Parkes’ inventions. By Stirling’s method, combining the iron with 
the zinc, in order to introduce it into the alloys, altogether precludes its 
use in any but those alloys in which a considerable portion of zinc is 
employed, such as brass or yellow metal. It could not be applied to any 
of those important alloys, of the nature of gun-metal or bronze, in which 
copper and tin are the chief ingredients, and which form some of the 
most valuable qualities of the manganese bronze; but an equally impor- 
tant difference in the manufacture of manganese bronze consists in adding 
the manganese in its metallic state, in the form of ferro-manganese, to 
the copper, by which the copper is cleansed from oxides as_ before 
explained, which cannot be the case when the manganese is reduced from 
the black oxide and combined with the copper, by one and the same 
operation, in the manner pursued by Parkes and Stirling. 
Another point of great importance is the very great nicety with which 
both the iron and manganese can be adjusted, and the effect controlled 
by adding the ferro-manganese to the copper, as pursued in the manu- 
facture of manganese bronze. The amount of manganese required for 
de-oxidising the copper and for permanent combination with it, having 
been ascertained by experience, it is found that very slight variations in 
quantity have a perceptible and ascertained effect in modifying the quali- 
ties of the alloys produced ; that is to say, the toughness can be increased 
and the hardness diminished, or vice versd, at will, precisely as is done in 
the manufacture of steel, by increasing or diminishing the dose of carbon 
and manganese. 
In preparing the ferro-manganese for use, that which is rich in manga- 
nese, containing say from 50 to 60 per cent., is preferred ; this is melted 
with a certain proportion of the best wrought-iron scrap, so as to bring 
down the manganese to the various proportions required. At the same 
time any silicon it contains is reduced and the metal refined. About four 
qualities are made in practice, containing from about 10 to 40 per cent. 
of metallic manganese. The lower qualities are used for those copper 
alloys in which the zinc exceeds the tin, and the higher qualities in which 
tin is used alone, or exceeds the zinc used in combination; and the 
amount of ferro-manganese added varies generally from about 2 to 4 per 
cent. 
After a number of experiments and tests; the Manganese Bronze and 
Brass Company, who are the sole manufacturers, have adopted the manu- 
facture of five different qualities of manganese bronze, although other 
varieties can be produced for special purposes. The distinctive features, 
peculiarities, and purposes for which these qualities are suited are as 
follows :— 
No. 1. In this quality the zinc alloyed with the copper is considerably 
in excess of the tin. It is cast into ingots in metal moulds, and then 
forged, rolled, or worked hot, and made into rods, plates, sheets, sheath- 
ing; and it may also be worked cold, and drawn into tubes, wire, &e. 
When simply cast, it has a tensile strength of about twenty-four tons per 
square inch, with an elastic limit of from fourteen to fifteen tons. When 
rolled into rods or plates, it has a tensile strength of from twenty-eight 
to thirty-two tons, with an elastic limit of twelve to twenty-three tons 
per square inch, and it stretches from 20 to 45 per cent. of its length 
before breaking. When cold rolled, the elastic limit rises to over thirty 
tons, and the breaking strength to about forty tons, and it still elongates 
about 12 per cent. before breaking. 
