BRICK, a kind of artificial stone, made of clay, molded. dried in the sun and baked in a kiln. The word is also applied to the block in its previous con dition as a molded plastic mass, and as a dried block in which the water hygro metrically combined with the clay is driven off. When this condition is ac cepted as a finality, the block so dried is an adobe. The burning of the previ ously dried brick drives off the chem ically combined water, and forever changes the character of the mass. Ari adobe may become resaturated with water, and resume its plasticity; a brick may become rotten and disintegrated, but not plastic. There are two principal kinds of brick, building brick and fire brick, and their composition depends upon the use to which they are put; a good building brick will contain about 50 per cent. silica, 25 per cent. alumina and oxide of iron, 3 per cent. carbonate of lime, 1 per cent. carbonate of mag nesium, and 21 per cent. of water and other constituents; while a fire brick will contain about 59 per cent. silica, 35 per cent. alumnia, 3 per cent. of oxide of iron, and only 3 per cent. of carbonate of lime, carbonate of Magnesia, and water, combined. Fire brick is used to line furnaces, crucibles, and in other places where a high heat is maintained; and must contain as little fusible matter as possible. Some of the best clays in the world for brick making are found in New Jersey, at Perth Amboy, Wood bridge, and Trenton, and one of the largest brick making establishments in the world is situated at Haverstraw, N. Y.
Building bricks come under various names according to the use to which they are put, or the position they oc cupy in a building. Some of these are: Air brick is an iron grating the size of a brick, or a perforated brick, let into a wall to allow the passage of air. Arch brick usually means the hard burned, partially vitrified brick from the arches of the brick clamp in which the fire is made and ma ntained. A brick made
voussoir shape 3 is known as a compass brick. A capping brick is one for the upper course of a wall; clinker, a brick from an arch of the clamp, so named from the sharp, glassy sound when struck; a coping brick, one for a cop ing course on a wall; feather edged brick, of prismatic form, for arches, vaults, niches, etc.; fire brick, made of intractable material, so as to resist fusion in furnaces and kilns; hollow brick, with openings for ventilation; stocks, a name given to the best class of bricks, and also locally to peculiar varieties, as gray stocks, red stocks, etc.; pressed brick another name for that class of stock brick, in which the process of manufacture has been to largely reduce the bulk of the plastic material by hydraulic pressure before burning, giving to the completed brick a smooth surface and great density of body. Pecking, place, sandal, semel brick, are local terms applied to imper fectly burned or refuse brick. Bricks vitrified by excessive heat are termed burr bricks or burrs.
Bricks were manufactured at a re mote period of antiquity by the Egyp tians, the Babylonians, the Assyrians, and some of them, being inscribed with written characters, have been of price less value in conveying historic facts to the present age. About A. D. 44, bricks were made in England by the Romans, and in A. D. 886 by the Anglo-Saxons under King Alfred. Under Henry VIII. and Queen Elizabeth the manufacture greatly flourished. The size was regu lated by Charles I. in 1625.
The following table gives the value of the brick output in the United States in 1918: