BRASS. An alloy of copper and zinc : to make brass, the English method is by melting together copper in round masses, or in bars, with calamine, which is a na tive oxyde or ore of zinc, and a native carburet of zinc combined with oxyde of iron, which make it of reddish color, and it usually contains more or less lead. The calamine is powdered and separated by washing, then heated on the hearth of a reverberatory furnace, which expels .ae volatile matter, usually water and carbonic acid. The remainder is oxyde of zinc, and a small portion of carbon, which the heat cannot wholly remove, and some earthy substances. The proportions are nearly equal weights of copper and cala mine and one-tenth of their weight of pulverized charcoal, which are together put into a crucible capable of containing 100 pounds of brass when completed, but when charged holding 663, calamine 93, and charcoal 13, which is covered with clay, sand, &c., to keep it free from the air. The fire is continued from twelve to twenty hours, when the refuse is poured off, the metal cast into ingots, then usually remelted and cast, to render it better and finer, when it is rolled, drawn, or made into castings for use. Brass is often made by melting toge ther small pieces of cast copper and zinc, which is made into ingots, then rolled into sheets slitted and drawn into wire. For knife scales, sheet brass is used which is not annealed, but stiff and hard. Corinthian brass, famous in antiquity, was an alloy of gold, silver, and copper. Lucius Numminus, 146 years before Christ, captured and burned the city of Corinth; and the violence of the confla gration formed, from the abundance of metals in its course, a solid sea of this alloy in the streets and low places. Ger man chemists make copper of a gold co lor, by exposing it to the fumes of zinc. Tho comparative stiffness of this alloy permits it to be cut by saws and files, turned and worked much easier than iron.
The metal anciently called brass, is the copper of modern times ; and the Colos sus at Rhodes, and other so-called brazen fabrics, were formed entirely of the last named metal.
Brass-making was introduced into Eng land in 1694, where it proved a failure to its first manufacturers, but it is now a great business in that country. Brass must be annealed after it is cast into moulds, or it will be so brittle that it cannot be drawn. Brass is lighter than pure copper, but it is harder. It is only malleable while cold. If brass is heated beyond a cherry red, the zinc separates from the copper in the form of gas. There are a great variety of brass alloys. Four parts of copper and two of zinc, makes a beautiful brass. The copper must be first melted then the zinc is introduced, and as soon as it is melted it must be stirred then run into the mould. The reason for doing this is, that zinc is volatilized at the beat of fluid copper, therefore, if the zinc and copper were in troduced together, before the copper was all melted a great portion of the zinc would have departed in the state of vapor.
The usual proportion of metals in yel low brass, is 30 of zinc and 70 of copper.
Tomback or red brass, is an alloy of copper and zinc containing not more than 20 per cent. of the latter.
Pinchbeck, is made of 2 parts copper and 1 of yellow brass.
Princes Metal, 3 parts copper and 1 3f zinc.
Mannheim gold, 28 copper, 12 yellow brass, and 3 tin.
Cast white metal-buttons, are made of an alloy of 32 parts brass (yellow), 4 parts of zinc, and 2 of tin.
The French state that brass containing two per cent. of lead works more freely in the turning-lathe, but does not ham mer so well as the ordinary brass.