MODERN BRONZES. 537 



phor-copper, phosphor-manganese bronze, phosphor-lead bronze, phos- 

 phor-tin, aluminum-bronze, silveroid, and cobalt-bronze. There are 

 also other bronzes which are used as substitutes for gold in cheap imi- 

 tation jewelry, but they do not come within the scope of the present 

 paper. 



The action of phosphorus on copper alloys is principally due to its 

 reducing qualities, by virtue of which the oxygen absorbed by the 

 molten metal is removed, or the oxides formed thereby are eliminated, 

 and the degree is imparted of homogeneity, strength, and toughness 

 peculiar to the chemically pure metal. The phosphorus, by producing 

 these effects, is converted into a cuprous oxide, which floats on the 

 surface of the molten metal in the shape of a very fluid slag, while the 

 superfluous quantity combines with the metal. It is not, therefore, 

 desirable to add to the bronze a larger quantity of phosphorus than 

 will suffice to reduce the oxide present. 



Phosphor-bronze was first prepared by Dr. Kunzel, of Dresden, and 

 was brought into practical use in England early in 1873. The alloys 

 of this class are composed of copper, tin, and phosphorus, and other 

 ingredients in variable proportions, and are made to be either as ductile 

 as copper, as tough as iron, or as hard as steel, according as the pro- 

 portions of the constituents are varied. The alloys used for rolling 

 and drawing have very different proportions from those employed for 

 castings, bearings, and parts of machinery. The castings of this metal 

 are perfectly sound and homogeneous. Wherever strength, toughness, 

 and durability are desired, phosphor-bronze is found to be better 

 adapted than gun-metal and brass, and in many cases than iron and 

 steel. Having the advantage of not becoming crystalline under the 

 action of repeated shocks and bendings, it is well adapted for making 

 wire-rope, and, not being acted upon by corrosive liquids or the atmos- 

 phere, its value as a metal remains constant. The principal varieties 

 of phosphor-bronze, which are produced by slightly varying the pro- 

 portions of the constituents, are phosphor-bronze duro A, a very dense 

 metal, adapted for bearings carrying heavy wheels running at great 

 velocities, and generally for all quick-speed purposes ; and phosphor- 

 bronze duro B, which is intended for the bearings of hot-neck rolls, 

 and for all bearings having to withstand great pressure. 



Silicium-bronze was invented by M. Lazare Weiller, of Angouleme, 

 in the search for a material for telegraph-wires, which, together with 

 all the desirable properties of phosphor-bronze, should have a better 

 conducting power. In it phosphorus is replaced by a silicious metal- 

 loid, by the incorporation of which a wire is produced offering the 

 same resistance to rupture as phosphor-bronze wire, by the use of 

 which telegraph lines may be furnished with a light, unoxidizable wire, 

 having all needed electrical efficiency. It is also affirmed of wires of 

 this bronze that they are of equal strength with ordinary wires, while 

 not one tenth as heavy ; and that, if broken, they will not fall to the 



