Stoneware
Coarse porcelain, a very hard kind of pottery made from clay containing ferric oxide and some lime, to which it owes its partial fusibility. The glazing is done by throwing common salt into the furnace; this is volatilized and decomposed by the joint agency of the silica in the object and of the vapor of water always present; muriatic acid and soda are thus produced, the latter forming a silicate, which fuses over the surface of the ware and leaves thereon a thin but excellent glaze. See POTTERY; PORCELAIN.