Clay (Name of various earths)

Collier's New Encyclopedia (1921)

the name of various earths, which consist of hydrated silicate of aluminum, with small proportions of the silicates of iron, calcium, magnesium, potassium, and sodium. All the varieties are characterized by being firmly coherent, weighty, compact, and hard when dry, but plastic when moist, smooth to touch, not readily diffusable in water, but when mixed not readily subsiding in it. Their tenacity and ductility when moist and their hardness when dry has made them from the earliest times the materials of bricks, tiles, pottery, etc. Of the chief varieties porcelain Clay, kaolin, or China Clay, a white Clay with occasional gray and yellow tones, is the purest. Potter's Clay and pipe Clay, which are similar but less pure, are generally of a yellowish or grayish color, from the presence of iron. Fire Clay is a very refractory variety, always found lying immediately below the coal; it is used for making fire bricks, crucibles, etc. Loam is the same substance mixed with sand, oxide of iron, and various other foreign ingredients. The boles, which are of a red or yellow color from the presence of oxide of iron, are distinguished by their conchoidal fracture. The ochres are similar the boles only more oxide of iron. Other varieties are to , containing fuller's-earth, Tripoli, and boulder Clay, the last a hard Clay of a dark-brown color, with rounded masses of rock of all sizes embedded in it, the result of glacial action. The distinctive property of as ingredients of the soil is their power OI, of absorbing ammonia and other gases and vapors generated on fertile manured lands; indeed no soil will remain fertile unless it portion best wheats of Clay in its composition. both in America and are grown on calcareous Clays, as also the finest fruits and flowers of the rosaceous kind. The following shows the value of the Clay industry in the United States for the calendar year 1919 (est.): Common brick Vitrified brick or block...... Face brick .. Fancy or ornamental brick.. Enameled brick $640,000 ... 10,420,000 Drain tile 16,170,000 Sewer pipe Architectural terra cotta.... 4,840,000 Fireproofing and hollow 16,620,000 building tile....... 7,250,000 Tile (not drain) 730,000 Stove lining 36,170,000 Fire brick Miscellaneous 7,100,000 .. .$184,650,000 Total brick and tile..... 76,140,000 Total pottery ... .$260,790,000 Grand total ... The total imports of Clay products in 1919 were valued at $7,366,535, of which $7,230,061 were pottery products, and $136,474 brick, tile, etc. In the same year the total exports were valued at $6,582,284.