CERAMIC WARE. 225 



actually be attenuated into a light invisible gas, some portion 

 of the wonder vanishes. 



Pure alumina combined with water (or, if we prefer to call 

 it so, pure clay) is almost infusible : for which reason no sort 

 of crockery could be manufactured out of it. The fusibility 

 of alumina, however, is promoted by mixture with almost any 

 mineral oxide, and also certain compounds not being mineral 

 oxides, of which borax is a familiar example. In this way 

 silica or flint promotes the fusibility of alumina ; and pure 

 silica being absolutely white, the mixture presents the farther 

 advantage of yielding a fictile ware upon which colours may 

 be deposited with facility. The very purest natural clays 

 are all mixtures of alumina with silica, in varying proportions. 

 Beds of such pure clay are, however, remarkably rare. Most 

 frequently some calcigenous oxide is found present ; as evi- 

 denced by colour. Whoever takes the trouble to pass men- 

 tally in review before the mind such clays as he may remem- 

 ber to have seen, will not fail to be struck with the fact, that 

 by far the majority of them are tinged with a brownish or 

 reddish hue an iron-rust hue, in point of fact and this cir- 

 cumstance may raise the suspicion, perfectly just, that the 

 colouring matter is rust or ' red oxide' of iron. 



It is commonly known that, from time immemorial, the 

 Chinese and Japanese have manufactured a very exquisite 

 sort of Ceramic "Ware : a material exquisitely white and per- 

 fectly translucent, as if (which is the fact) partial fusion of 

 the body of the material had been effected. Not the slightest 

 tint of red, indicative of oxide of iron, is present in Oriental 

 China ware. This is dependent on the happy chance that 

 in China and Japan there were discovered, at very remote 

 periods, beds of aluminous and siliceous materials wholly free 

 from oxide of iron. 



The inhabitants of India, to whose art-labours Europe 

 owes so much, did not possess these pure white materials : or 

 at least, if they possessed them, never discovered and made 



Q 



