Brass
A yellow alloy of copper and zinc, much used for furnishing and decorating, as well as for parts of machinery. It is common to include other alloys, as copper and tin in this classification; these, however, are not brass, but bronze, and will be found described under that head. When brass is manufactured on a large scale, it is usually made to contain: copper 2, zinc 1; but the alloys must necessarily vary according to the purposes for which they are intended. If more than ordinary tenacity is required the alloy must consist of about: copper 16, zinc 4; but if a hard, brittle alloy possessing reduced resisting power is desired, the zinc may be increased to equal quantity with the copper, or even beyond that where, at copper 1, zinc 2, the yellowness ceases entirely, and we have a brilliant bluish-white alloy of so crystalline a nature that it may be crushed in a mortar. The method of manufacturing brass in large quantities is to heat in crucibles a mixture of calamine, or carbonate of zinc, charcoal, and scrap, or grain copper, in the proportions thus: calamine and charcoal 3, copper 2. The action of the white heat reduces the calamine, and separates the zinc, which, combining with the copper, forms a brass consisting of copper 2, zinc 1. Common ingot brass is made by the simple fusion of copper 16, zinc 8; but, owing to the volatility of zinc, the resultant proportions of the alloy are seldom to be relied upon, and calamine brass is preferred. The vapor of the zinc-ore by the latter mode combines more intimately with the copper. Yellow brass for filing and machining ranges from: copper 16, zinc 4, to copper 16, zinc 9. Up to this proportion brass remains very ductile and malleable; beyond it, the crystalline nature asserts itself in proportion as the zinc is increased. Copper and zinc mix in all proportions, but it requires the greatest care in mixing to obtain the proportions aimed for, owing to the zinc's volatility, as before stated.
With reference to the color of brass alloys, copper-red gives place to yellow at copper 16, zinc 4, and maintains about the same hue up to copper 16, zinc 10; when it gradually becomes lighter up to copper 1, zinc 2--which as before stated, is a bluish-white with a brilliant silvery lustre when polished. The fusibility of brass increases with the zinc; so that the metal from copper 16, zinc 7, up to copper 16, zinc 15, is eminently adapted for running a large class of furnishing and decorative-work; but before such brittle metal as this is subjected to the various processes of cleaning, dipping, lacquering, and bronzing, it is invariably annealed.
The specific gravity of brass is greater than that deducible from the specific gravity of the metals composing it.
The brass for ornament is prevented from tarnishing by lacquering and bronzing. The former consists of coating with shellac in spirit, with some coloring; the latter process being affected by the application of metallic solutions, after a course of cleaning in acids.
Brass from copper 50, zinc 50, to copper 63, zinc 37, may be rolled into sheets and otherwise worked when heated to a red heat; but, according to Muntz, copper 60, zinc 40, is the best proportion. When brass is made for this purpose it is cast into ingots, then heated and rolled. Brass is made hard by hammering or rolling, but its temper may be again drawn by heating to a cherry-red and plunging it in water. Copper-castings are, to a great extent, freed from porosity or honeycombing by the addition of from 1/2 to 1 ounce of zinc to 16 ounces of copper. The following compositions are alloys of copper and zinc only, which constitute true brass:
COPPER AND ZINC ALLOYS.
Copper. Zinc.
Copper castings are made solid by. . . . . 16 1/4 to 1 Brass gilt for jewelry, etc., bronze color . . . . . 16 1 to 1 1/2 Heavy Machinery bearings . . . . . 32 1 Sheet brass, red . . . . . 16 3 Tough engine brass . . . . . 20 3 Brass to imitate gold . . . . . 16 3 1/2 to 4 Bristol brass, solders well . . . . . 16 6 Brass wire . . . . . 16 7 Brass castings, ordinary . . . . . 16 8 Muntz metal (one extreme) . . . . . 16 9 to 10 1/2 Muntz metal (one extreme) . . . . . 16 16 Pale-yellow brass for dipping (spelter solder for copper or iron) . . . . . 16 12 Another dipping-brass . . . . . 16 14 Spelter solder for brass . . . . . 16 16 Speculum metal . . . . . 100 18 3/4 Mosaic gold . . . . . 32 33 As a supplement to the above, the author appends the following list of mixtures, which are largely original, and of known excellence for the numerous purposes mentioned:
MISCELLANEOUS MIXTURES FOR GENERAL MACHINERY PURPOSES, ETC. Copper. Tin. Lead. Zinc.
Soft Machinery brass . . . . . 16 2 5 Large steps or bearings (common) . . . . . 16 2 2 2 Large steps or bearings (good) . . . . . 16 3 1 1 Large steps or bearings (best) . . . . . 16 4 Small steps or bearings . . . . . 16 2 1 1/2 1 Ordinary D valves . . . . . 16 2 1/2 2 1/2 Extra large D valves. . . . . 16 1 1/2 1 1/2 Delivery valve-lids . . . . . 16 2 2 1 Large bells . . . . . 16 4 1/2 Large bells . . . . . 16 3 1/2 Small clock-bells . . . . . 16 3 General machinery brass . . . . . 16 2 1 1/2 General machinery brass (good) . . . . . 16 2 1/2 1/2 General machinery brass (collars, etc.) . . . . . 16 2 1/2 1 1 Large cocks . . . . . 16 1/4 9 Small cocks . . . . . 16 1 5 Common cocks . . . . . 16 1 1/2 6 Yellow brass . . . . . 16 8 Yellow brass (good) . . . . . 16 7 Yellow brass (better) . . . . . 16 6 Brass for cutting-wheels . . . . . 16 4 Roller brass . . . . . 16 2 3 Large copper rivets . . . . . 16 1 Small copper rivets . . . . . 16 1/2 Lathe-bushes . . . . . 16 4 1/4 Pulley-blocks . . . . . 16 2 1/2 Wheels . . . . . 16 2 Gun-metals . . . . . 16 1 3/4 Connecting-rod steps . . . . . 13 1 1/2 1 1/2 Valve-spindles . . . . . 16 1/2 3 Valves and seatings . . . . . 16 3 1 Piston-rings . . . . . 30 4 1/2 15 Brass to expand by heat equal with iron . . . . . 79 6 15 For further information on this subject, see ALLOY; BRASS-FURNACE; BRASS-MOULDING; BRASS-TEMPERING; BRASS-SCRAP; BELLS; BRONZE; CEMENTATION; COPPER; SHEATHING-METAL; SOLDERS; LACQUERING; ZINC; GASBLAST FURNACE; PORTABLE FURNACE; HARD ALLOY.