Page:Encyclopædia Britannica, Ninth Edition, v. 4.djvu/259

Rh saviour of Sparta in the early period of the war, and had he lived the contest might have come more quickly to an end.  BRASS, an alloy of copper and zinc, the composition of which will be discussed under the heading. In this place we have to do simply with its hiatory, and the various applications of the alloy in the arts. Although the term brass frequently occurs in Scripture from the era of Job downwards, there is no indication that brass, as known in modern times, was in use previous to the period of the Roman empire. By the Romans a compound was used under the name oricalchum or auricalchum, which appears to have possessed the composition and properties of brass. With their conquests they carried a knowledge of the arts they cultivated into the countries they subdued, and from these the art of preparing the alloy extended with civiliza tion throughout Europe. The earliest traces of brass in Great Britain are found in the mediaeval monumental &quot;brasses,&quot; found commonly over the tombs of civil and ecclesiastical dignitaries (see ). That the alloy was manufactured in England during the reign of Henry VIII., however, is indicated from the passing of an Act of Parlia ment prohibiting, under severe penalties, the export of brass, a prohibition which was not withdrawn till so recent a date as 1799, During the reign of Queen Elizabeth the manufacture was systematically developed and extended, and a patent for working calamine stone (the principal ore of zinc) and making brass was granted by the queen to William Humfrey and Christopher Schutz, securing to them the exclusive right of manufacturing brass. The patent rights granted to these persons were gradually ex tended and merged into a company under the name of the &quot; Governors, Assistants, and Societies of the City of London of and for the Mineral and Battery Works,&quot; which con tinued to exercise its functions down to the year 1710. In the year 1721 it was estimated that about 30,000 persons found employment in the brass industries. From a very early date brassfounding was prosecuted in Birmingham, and by degrees it there assumed more important proportions till it has become the most distinguishing industrial feature of the town. The late Mr W. Aitken, in his valuable report on brass and brass manufactures, to which source of practical information we have to express our obligation, says : &quot; What Manchester is in cotton, Bradford in wool, and Sheffield in steel, Birmingham is in brass ; its articles of cabinet and general brass- foundry are to be found in every part of the world ; its gas-fittings in every city and town into which gas has been introduced from Indus to the poles.&quot; (Birmingham and the Midland Hardivare Districts, London, 1865.) The brass trade of the present day is, according to Mr Aitken, conducted under nine different heads : (1), brass-casting; (2), cabinet, bell, and general brassfoundry ; (3), cock-making and plumbers brassfoundry; (4), stamped brassfoundry; (5), rolled brass, wire, and sheathing; (6), tube-making; (7), lamp-making; (8), gas-fittings; and (9), naval brassfoundry. It frequently happens that several of these departments are carried on in the same establishment ; but numerous as are these divisions, they by no means exhaust the industries in which brass plays a principal part. Thus the pin manufacture, button-making, and the gilt jewellery trade, are eminently characteristic of Birmingham, and in these brass is the principal metallic substance employed. According to the different forms under which brass is to be employed it is fashioned by the various processes of 1st, casting; 2d, rolling and drawing; 3d, stamping; and 4th, tube-drawing and casing; and to these, with 5th, brass-finishing, we shall briefly allude.

Casting.—The first operation necessary in connection with casting is the preparation of patterns of the object to be cast. Castings, of course, vary in all degrees in intricacy and elaboration of details, and the getting up of the more ornamental patterns necessitates the employment of persons of artistic ability to prepare the design, and superior artisans to finish the pattern blocks. Three classes of castings are recognized in the trade 1st, common castings, made from any plain pattern, an impression of which can be formed and the pattern taken out without breaking the mould ; 2d, cored castings, such as plumbers cocks and other tubular work, where the metal must be poured round a central core ; and 3d, false-cored castings, where the pattern is so undercut that the mould must be built up of such a number of separable sections as the intricacies of the pattern may require. When the mould is formed each of these sections is lifted off, the pattern is taken out, and they are then built together in their original position. This descrip tion of moulding requires much skill and dexterity. Moulds are made in sand of a free, fine-grained, and uniform character ; and moulding-boxes of wood or cast-iron which fit together in two or more parts, with moulding-boards of wood and clamps to hold the parts together, are employed in casting. In the forming of common castings, the lower division of the moulding-box is packed with sand, and the pattern, if deep, is driven half its depth into it, parting sand is dusted over the surface, and the upper part of the box is fitted on and similarly packed with sand. When the box is filled, a moulding-board, forming a top or bottom to it, is laid on, the two halves of the box are separated, the pattern with drawn, and &quot;gates&quot; or channels formed between the mould and the aperture by which the metal is poured in. The sur faces are then dusted over with flour or powdered charcoal, and the mould placed in an oven to dry. On their with drawal from the oven the two parts of the moulding-box are clamped together, the molten metal is poured in, and a perfect copy of the pattern produced. In making common castings as many patterns as the superficial area of the moulding-box will accommodate are cast at once, &quot;gates&quot; leading to the entire series ; and for many plumbers cast ings, &c., a series of half patterns, with moulded gates, are fixed on two sides of a plate by which the whole may be moulded and finished at one operation. The cores for tubu lar work are separately made, and are supported on bearings in the mould. When the casting is cold the hardened core is picked out, and the article is then ready for finish ing. Fine ornamental castings which contain minute details are moulded with special care in very fine sand, faced with charcoal powder, which faithfully reproduces the most delicate lines. The metal is poured direct from the crucible in which it is prepared, by the aid of strong tongs, and all spilt metal is carefully swept up, cleaned, and remelted.

Sheet Rolling and Wire Drawing.—The raw material of a large proportion of the brass trade consists of sheet-brass, as from it stamped work of all kinds is prepared, and jointed tubing and sheathing are made ; and, generally, the processes of rolling must be adopted when sheets of large dimensions or of great thinness are required. For tho purpose of rolling the metal is melted and cast in broad flat moulds of cast-iron ; and in cases where a large quantity is dealt with, the moulds are hewn out in granite. These moulds are rubbed with oil and powdered with charcoal before being used. The ingots for rolling, termed &quot; strips,&quot; are in the cold state passed successively between rolls (pairs of chilled-iron cylinders) of large size which squeeze them out and extend them lengthwise. As often as necessary in the process the sheet is annealed in a muffle or reverberatory furnace, being allowed to cool down after each annealing. The sheet is finished, after &quot; pickling &quot; in acid, by passing it through a pair of highly polished rolls. Muntz s sheathing metal is a form of brass containing a large proportion of 