23^ POTTERY- 



The bla^k *ware owes its colour to the oxides of 

 of iron and manganese. It has also less flint, and 

 is more burned ; its compactness renders glazing 

 unnecessary. 



Porcelaifi, called also CImia, from being first 

 brought from China, is the most beautiful and per- 

 fect species of earthen-ware. 



Genuine or true porcelain, is a semi-vitrified 

 earthen-ware, intermediate between common ware 

 and glass. It is infusible in the strongest fire ex- 

 cited in furnaces ; it is hard, but not so brittle as 

 glass : it is proof against sudden changes of heat 

 and cold : it is fine grained, and dense without 

 gloss in the fracture, and is translucent. The 

 Chinese long excelled in the art of making porce- 

 lain, but it is now made in various parts of Europe 

 of an equally good quality and more ornamental. 

 The Chinese porcelain is said to be composed of 

 two ingredients, one of which is a hard stone called 

 pehmtse, which is carefully ground to a very fine 

 powder ; and the other, called kaoIi?i, is a white 

 earthy substance which is intimately mixed with 

 the ground stone. 



Several compositions of mingled earths may 

 yield a true porcelain, by being burnt; and the 

 porcelain of various countries differ in their mix- 

 tures. But the principal basis of any true porce- 

 lain is that kind of clay M'hich becomes white by 

 baking, and which, either by intermingled hetero- 

 geneous earth, or by particular additions undergoes 

 in the fire an incipient vitrificatior,, in which the 

 true nature of porcelain consists. Feldspar and 

 gypsum, if added, may give that property to in- 

 fusible clay. 



When porcelain is to be made, the clay is pro- 

 perly selected, carefully washed from impurities, 



