Brass is an alloy of copper and zinc in about the proportions of copper 66%% and zinc 331/2%. Brass is extensively employed in the arts in the manufacture of scientific apparatus and mathematical instruments, the small parts of machinery, and many sorts of hardware. It is also drawn into wire, and rolled into sheets. and rods, which arc used for a multitude of pur poses. Brass is harder than copper, very malle able and ductile, and can he "struck" in dies. formed in molds, or "spun" in lathes into vessels. of a wide variety of forms. It is a much poorer conductor of electricity and heat than copper. and is more fusible. Aluminum brass is made of equal weight of aluminum bronze, copper, and zinc. It has a very high tensile strength, and has been used for screw propellers.
Other alloys than bronzes and brasses exist in au immense variety, and have numerous applica tions in the arts and sciences, although they are much less used than the bronzes and brasses. Only a few of these alloys can be mentioned. here. German silver is an alloy of copper, zinc. and nickel in the respective proportions of about 60%, 20% and 20%. it is used for table utensils, ornaments. and in the form of sheets, and is• one of the most difficult alloys to handle in the foun dry and rolling mill. Pewter is an alloy of tin and copper often mixed with lead. Britannia -metal is an alloy of tin, antimony, copper, and brass. It and pewter are much used in making table utensils. Stereotype metal is an alloy of 16% antimony. 17% tin and 07% lead. (See PRINT ING.) Babbitt metal is an alloy • of 4 parts copper. 12 parts tin, S parts regulus of antimony melted together, and 12 parts tin added after fusion. It is used for lining bearings for jour nals. Solders are alloys used for joining metal lic surfaces and parts. and have a wide range of composition. The soft solders are made of tin and lead : the hard solders are usually made of brass. and special solders are composed of vari ous alloys of copper, zinc, lead. tin, bismuth. gold. and silver. In making solders, great care
has to be taken to secure uniformity of composi tion. For this reason, they are often granulated by pouring from a height into water, or by re (hieing the cast ingots into powder and then re melting the granulated or powdered material. The soft solders are usually sold in sticks, and silver and gold solder in sheets. Platinum is sol dered with gold, and German silver with a solder of equal parts of silver, brass, and zinc. The es sentials of a good solder are that it shall have an affinity for the metals to he united, shall melt at a considerably lower temperature, shall he strong, tough, uniform in composition, and not readily oxidized. Type metal is an alloy of lead and antimony in the proportions of 4 to I. It is a hard alloy capable of being cast in molds. and taking form very perfectly. Gold coin consists of an alloy of 900 parts gold, 75 parts copper, and 25 parts silver. Iron forms compounds with many elements that are used in metallurgical processes, as ferromanganese, fer•o-titanium, and ferro-tungsten, which will be considered under IRON AND STEEL. Mercury com bines with many metals to form amalg,ams(q.v.). During the years 1875-78, a board for testing iron, steel, and other metals met at the Water town Arsenal. Mass.. and very thoroughly consid ered the properties of various alloys, including a series of experiments on the characteristics of metallic alloys, and investigation of the laws of combination. Their report, published in 1881, contains much information on the subject., to gether with a bibliography. Consult: Guet tier, .4 Practical Guide for the Manufacture of Metallic Alloys, translated by Fesquet (Phila delphia, 1872) Larkin, The Brass and Iron Founders' Guide (Philadelphia, 1878) ; Graham, The Brassfoundcrs' Manual (London, 1879) ; Brannt, Metallic Alloys (London, 1889) ; Morns, Mixed Metals. or Metallic Alloys (New York, 1890) ; and Thurston, A Treatise on Brasses, Bronz-es. and Other Alloys and Their Constituent Metals (New York, 1897).