ON MANGANESE BRONZE. ; 379 
brought forward an alloy made in a similar manner. No comparative 
experiments as to the strength, hardness, or ductility, or other qualities 
of these alloys, have come under my notice; but I believe the only effect 
of the manganese alone that I can discover is to add somewhat to the 
toughness and ductility of the alloys, and allow copper and zine of a 
somewhat inferior quality to be used in the manufacture of brass and 
other similar alloys, which, without the manganese, would not stand the 
working necessary to shape them into the various articles for which they 
were destined. 
Mr. Morries Stirling, in 1848, however, proposed to use manganese in 
various brass alloys in which iron was present, but in a very different 
manner from that employed by me. Mr. Stirling first combined about 
7 per cent. or less of iron, with the zinc, and added to the copper a small 
percentage of manganese by reducing the black oxide of manganese with 
the copper, in the presence of carbonaceous materials, and then added 
to it the requisite quantity of the iron and zinc alloy to make the improved 
brass required. Mr. Stirling described a method of combining the iron 
with the zinc by fusion, but in practice he found a more ready means of 
procuring the zinc and iron alloy by employing the deposit found at the 
bottom of the tanks used for containing the melted zinc for galvanising 
iron articles; this product consists of zinc with from 4 to 6 per cent. 
of iron, bat this percentage is very variable, and this material is useless 
if the amount of iron is required to be adjusted with accuracy. Another 
great drawback to this class of alloy is the great difficulty of producing 
sound castings of them in sand moulds with any certainty. 
These, then, were the chief inventions that have come under my 
notice at all approaching mine in character, or similarity, at the time I 
introduced it, which invention I now proceed to describe. 
The manganese bronze is prepared by introducing and mixing with 
the copper, to be afterwards made into alloys similar to gun-metal, 
bronze, brass, or any other alloy, of which copper forms the base, a small 
proportion of ferro-manganese. The ferro-manganese is melted in a 
separate crucible, and is added to the copper when in a melted state, and 
at a sufficiently high temperature. 
The effect of this combination is similar to that produced by the addi- 
tion of ferro-manganese to the decarburised iron in a Bessemer converter ; 
the manganese in a metallic state, having a great affinity for oxygen, 
cleanses the copper of any oxides it may contain, by combining with 
them and rising to the surface in the form of slag, which renders the 
metal dense and homogeneous. A portion of the manganese is utilised 
in this manner, and the remainder, with the iron, becomes permanently 
combined with the copper, and plays an important part in improving and 
modifying the quality of the bronze and brass alloys, afterwards prepared 
from the copper thus treated; the effect being greatly to increase their 
strength, hardness, and toughness; the degrees of all of which can be 
modified at will, according to the quantity of the ferro-manganese used, 
and the proportions of the iron and manganese it contains. By these 
variations, together with variations in the proportions of copper, tin, and 
zine employed, a most valuable group of new alloys has been produced, 
possessing qualities in the way of strength, hardness, toughness, &c., far 
beyond anything yet obtained in any similar alloys. 
It will be seen that the process described of making the manganese 
bronze is altogether different, both in principle and effect, from Stirling’s 
