XV 



Grow an Clay Kaolin 169 



The Cornish Clay called also the Porcelain or 

 Growan Clay was suitable for many purposes for 

 which the Staffordshire clays were unsuitable. It 

 was sent by sea from Saint Austell to Liverpool, and 

 from thence the materials for hard porcelain, mortars, 

 crucibles, and pyrometers, were sent on to Etruria, to 

 be worked into their proper forms. Hard porcelain was 

 of so much importance in the manufacture of china that 

 it is necessary to make some special reference to it. 

 Moreover, Wedgwood afterwards made a driving tour to 

 the West of England in search of this porcelain clay. 



Porcelain was manufactured in China from which 

 country it obtained the name which it still retains 

 long before it was known in Europe. Hard porcelain is 

 said to have been invented at Sin-ping in China, as 

 long ago as 185 years before Christ. It was imported 

 into Europe through means of the Arabs, and was sold 

 at very high prices. Kaolin was the name given by 

 the Chinese to the fine white clay which they use in 

 making their porcelain. It is produced by the decom- 

 position of a granite rock, the constituents of which are 

 quartz, mica, and felspar the whole having gradually 

 mouldered into kaolin by the joint action of air and 

 water. 



A very similar clay occurs in the south of Cornwall, 

 produced by the decomposition of Pegmatite a granite 

 in which there is scarcely any mica and very little 

 quartz. A similar clay is found at St. Yrieux la Perche, 

 near Limoges, in France ; at La Doccia, near Florence ; 



