KAOLIN, a pure white clay, know also as china-clay, since it is an essential ingredient in the manufacture of china, or porcelain. The word kaolin, formerly written by some authors caulin, is said to be a corruption of the Chinese _Kau-ling_, meaning "High Ridge," the name of a hill east of King-te-chen, whence the earliest samples of the clay sent to Europe were obtained by the Pere d'Entrecolles, a French Jesuit missionary in China in the early part of the 18th century. His specimens, examined in Paris by R. A. Reaumur, showed that true porcelain, the composition of which had not previously been known in Europe, contained two essential ingredients, which came to be known--though it now appears incorrectly--as kaolin and petuntse, corresponding respectively to our china-clay and china-stone. The kaolin confers plasticity on the paste and secures retention of form for the ware when exposed to the heat of the kiln, whilst the petuntse gives the translucency so characteristic of porcelain. Some of the earliest discoveries of kaolin in Europe were at Aue, near Schneeberg in Saxony, and at St Yrieix, near Limoges in France. In England it was discovered in Cornwall about the year 1750 by William Cookworthy, of Plymouth; and in 1768 he took out his patent for making porcelain from moorstone or growan (china-stone) and growan clay (kaolin), the latter imparting "whiteness and infusibility" to the china. These raw materials were found first at Tregonning Hill, near Breage, and afterwards at St Stephen's in Brannel, near St Austell; and their discovery led to the manufacture of hard paste, or true porcelain, at Plymouth and subsequently at Bristol.