KAOLIN

the name given to any white clay suitable for the manufacture of porcelain. The word is derived from the Chinese Kau-ling, the name given to the white, earthy material used in the manufacture of porcelain at King-te-chin, and mined in the Kau-ling Hills. Originally the name ‘kaolin’ was applied only to those clays containing a high percentage of the mineral Kaolinite, a hydrated aluminum silicate, having the formula H4A12 8i200, but while most china clays approximate, in composition, the formula given above, few of them contain the mineral kaolinite in sufficient quantities to be definitely identified. The kaolin of commerce, therefore, consists of white clay po e ing the property of forming a plastic ma when mixed with water, and containing a mixture of hydrated aluminum silicates, with small quantities of free silica,'felspar and mica, Clays are of two varieties—residual and sedimentary. Residual clays are formed by the breaking down and decomposition of rocks, and they are found adjacent to the rock ma es from which they origtnated. The breaking down is brought about by water. Sedimentary clays are formed by deposits carried down by rivers from distant points. Kaolin is usually residual clay, and is found in Cornwall_and Devon, in England, in France, Bohemia, the United States, South Africa and other parts of the world. To free the clay from grit, {t is mixed with water, the grit allowed to settle, and the finer particles floated off. Kaolin, besides being used in the manufacture of china and porcelain, forms the filler for many grades of paper, and is also employed in the finishing of calico and| the coating of paper. town, S. Australia. Pop. 2,000. »+ E.), native state, Punjab, India; area, c. 635 sq. miles. Pop. 270,000.