538 THE POPULAR SCIENCE MONTHLY. 



ground as ordinary wires do, but, by virtue of their high elasticity, 

 will spring back and coil up close to the standards. 



It has long been known that the hardness of bronze could be in- 

 creased by adding iron to it, but that quality appears to be acquired 

 at the expense of ductility and toughness, and for that reason, prob- 

 ably, such alloys have never come into general use. Mr. Alexander 

 Parkes, and the late Mr. J. D. Morries Stirling, were probably the first 

 to propose and carry into practice the use of manganese for improving 

 the quality of bronze. Mr. Parkes combined manganese alone with 

 copper, and used this alloy to form improved alloys of brass and yel- 

 low metal, of which to make sheathing, rods, wire, nails, and tubes. 

 Mr. Stirling, in 1848, proposed to employ manganese in various brass 

 alloys in which iron was present ; and a metal introduced by him was 

 used for some time in railway-carriage bearings. It, however, lacked 

 strength, hardness, and ductility, and has long since been superseded. 



A manganese-bronze having all the requisites of a useful alloy was 

 introduced in 187G by Mr. P. M. Parsons. It is prepared by mixing 

 a small proportion of ferro-manganese with copper, after which various 

 alloys are formed. The ferro-manganese is melted in a separate cru- 

 cible, and is added to the copper when in a fluid state. The effect of 

 this combination is similar to that produced by the addition of ferro- 

 manganese to the decarburized iron in a Bessemer converter. Accord- 

 ing to Mr. Parsons, while a part of the manganese cleanses the copper 

 of any oxides it may contain by combining with them and forming a 

 slag, another part, with the iron, becomes permanently combined with 

 the copper, whereby the strength, hardness, and toughness of the com- 

 pound are modified, according as the proportions of the constituents 

 are varied. Five different qualities of manganese-bronze are made. 

 In the number one quality the zinc alloyed with the copper is consid- 

 erably in excess of the tin. It may be worked hot or cold, and has 

 great tensile strength and elasticity. Manganese-bronze number two 

 is stronger, and can be cast in sand for special purposes where strength, 

 hardness, and toughness are required ; but it has to be melted in cru- 

 cibles. One of its most important applications is to the production of 

 articles cast in metal molds under pressure ; and the articles thus 

 made have the strength, toughness, and hardness of cast-steel, without 

 any of its defects. It is perfectly homogeneous, and, while not pos- 

 sessing a fibrous texture derived from rolling or hammering, is still 

 fibrous in character, in all directions alike, and, when broken, shows a 

 beautiful silky fracture. It can be cast upon any object, on which it 

 will shrink with a force equal to its elastic limit, and, when released, 

 will show an amount of resilience about double that of steel. Its hard- 

 ness is about equal to that of mild steel. 



The number three quality is composed chiefly of copper and tin in 

 about the same proportions as gun-metal, combined with a large per- 

 centage of ferro-manganese. Its chief characteristics are great trans- 



