Page:The American Cyclopædia (1879) Volume V.djvu/324

 320 COPPERAS COPPERHEAD advantageous or economical to alloy copper with other metals. Thus, with zinc it forms brass; with tin, bronze and bell metal; and with zinc and nickel, German silver. An alloy of copper with from 5 to 10 per cent, of alu- minum is known by the name of aluminum bronze, and from its golden yellow color, its great hardness and elasticity, and its resistance to oxidation, is susceptible of very many ap- plications both useful and ornamental in the arts. It has lately been found that the union with copper of small portions of phosphorus imparts to this metal great hardness and great strength, so that it has been proposed to use the new phosphorus bronze, as it is called, for the manufacture of large guns. Small quanti- ties of copper are alloyed with gold and with silver to harden these metals, both for the pur- poses of coinage and for various articles of manufacture. A minute portion of copper has been found in the human body, and is con- sidered a normal constituent. Sulphate of copper (but not copper itself) is used in medi- cine as an emetic in the dose of about two grains, acting rapidly and safely. In smaller doses it is an astringent. Externally it is ap- plied to chronic granulating surfaces as an astringent and stimulant. In appropriate cases it is better than the nitrate of silver. When poisoning has taken place from this or other soluble salts of copper, the symptoms are chiefly those of gastro-intestinal irritation. Under these circumstances, milk and eggs should be administered, by which less soluble combinations of the metal are formed with the caseine and albumen they contain. The best antidote is ferrocyanide of potassium, which forms with the poison an insoluble ferrocyanide of copper. The existence of a form of chronic poisoning due to the gradual absorption of copper compounds, and analogous to lead poisoning, has not been satisfactorily estab- lished. See COPPEB MINES, and COPPEB SMELTING. COPPERAS (Fr. couperose), a metallic salt, known also as green vitriol. It is a hydrous ferrous sulphate or protosulphate of iron, and is represented by the formula Fe,SO4,7HO. It forms pale green transparent prismatic crystals, which are very soluble in water. When exposed to a gentle heat they lose their water of crystallization and are converted into a whitish pulverulent mass. Copperas slowly absorbs oxygen from the air, with the forma- tion of a basic sulphate of peroxide of iron, of a rusty reddish yellow color ; this change takes place more rapidly when it is dissolved in water. Copperas has a peculiar metallic styptic taste, which belongs to the other pro- tosalts of iron. It is largely used in the arts for dyeing black, and in the manufacture of ordinary black writing ink. It is also em- ployed in photography as a reducing agent, and in many other chemical processes. Pure cop- peras may be obtained by dissolving metallic iron in dilute sulphuric acid ; hydrogen gas is evolved, and a green solution is obtained, from which crystals are got by concentration and cooling. In this way considerable quantities of copperas are manufactured from the refuse sulphuric acid which has been employed in the refining of petroleum. The chief supply of copperas is however obtained from the oxida- tion of the native sulphides of 'iron, some of which spontaneously absorb oxygen from moist air, and become covered with an efflorescence of copperas. In the case of other varieties of pyrites, which are less readily oxidable, they are first subjected to a partial calcination, by which a part of the combined sulphur is ex- pelled, and then piled up in heaps, which are frequently moistened and lixiviated with water from time to time. The solutions thus ob- tained are concentrated by evaporation over a fire in lead or iron tanks, and then led into crystallizing vats, where the copperas separates on cooling in large masses of fine green crystals. The process of oxidizing a large quantity of pyrites is very slow, and requires many months or even years for its completion. Large quan- tities of copperas are manufactured by this method at Stratford in Vermont. COPPERHEAD (trigonocephalus contortrix, Linn. ; genus aglcistrodon, Bd. and Gd.), a North American venomous serpent, the most danger- ous after the rattlesnake. The head is thick and triangular ; it has a pit between the eye and the nostril ; the upper jaw furnished with poi- sonous fangs; the eyes large, and the orbital plates projecting; the iris is bright golden with a reddish tinge. The neck is contracted, and its scales are smooth ; the body long, thick to near the tail, and covered above with rhomboidal carinated scales, except the lower rows, which are smoother ; the last abdominal plate is very large ; there are no rattles, the tail being short and conical, ending in a horny tip. The general color above is a light nut- brown, with transverse bars of dark brown, narrowest in the middle, broad and bifurcated on the sides ; the under parts are flesh-colored, freckled with minute dark brown spots; near the flanks are rounded dark blotches, corre- Copperhead. spending to the bifurcations of the dorsal bars. In a specimen 26 inches long, the head mea- sured a little more than an inch hi length by 11 lines in width ; length of body 21 inches,