FICTILE MANUFACTURES. 



china-clay, and oxide of tin in reducing its 

 strength ; the brown, by ochre, manganese, and 

 cobalt ; the black, by chromate of iron, nickel, 

 ironstone, and cobalt ; the green, by chrome, 

 oxide of copper, lead, flint, and ground glass ; and 

 the pink, by chrome oxide of tin, whiting, flint, 

 ground glass, and china-clay, which are mixed in 

 various proportions, fused together at a high tem- 

 perature, then pounded and mixed with oil. The 

 colouring matter is ground upon a porphyry slab, 

 with a varnish prepared from a pint of linseed oil 

 boiled very thick, four ounces of rosin, half a 

 pound of tar, and half a pint of the oil of amber. 

 This transfer varnish is very tenacious, and 

 requires to be liquefied by heat before being used. 

 The figure or design to be fixed upon the vessel 

 is engraved in the usual way upon copper-plate, 

 which is rubbed over with the colouring matter 

 prepared as above, and the impression is taken 

 upon a thin unsized paper made for the purpose. 

 The printed paper is placed upon the vessel, and 

 is nibbed with a roll of flannel about an inch and 

 a half in diameter. After this the vessel is set 

 aside for a little, to allow the figure to become 

 fixed, when it is dipped in water, and the paper 

 washed off with a sponge. The impression being 

 transferred, the vessel is dipped in alkali to destroy 

 the oil, and then immersed in the glazing matter. 

 Printing above the glaze is performed by covering 

 the copper-plate with the colouring matter as 

 before, and brushing off what is superfluous. A 

 cake of glue, stiff enough to be handled, is then 

 laid upon the plate, which receives the impression 

 of the figure. The glue cake must be very 

 cautiously lifted off from the plate, and transferred 

 to the surface of the glazed ware which it is 

 intended to print. The same cake will answer 

 for transferring a number of impressions, by 

 simply washing its surface. 



STONEWARE. 



This is a ware intermediate between common 

 earthenware and porcelain, and may be described 

 as a coarse kind of porcelain. The glazing for 

 the commonest kinds is performed by throwing 

 common salt into the heated furnace ; this is 

 volatilised and decomposed by the joint agency 

 of the silica of the ware and of the vapour of 

 water always present ; hydrochloric acid and soda 

 are produced the latter forming a silicate which 

 fuses over the surface of the ware, and gives a 

 thin but excellent glaze. The salt is not thrown 

 in until the kiln has been raised to its greatest 

 necessary temperature. 



Stoneware of the Wedgwood kind is a semi- 

 vitrified ware, which is not susceptible of a super- 

 ficial glaze. It contains barytic earths, which act 

 as a flux upon the clay, and form an enamel, or 

 by the clay being rubbed over with a compound 

 vitrifying paste. Messrs Doulton and Watts, of 

 the Lambeth Pottery, London, have lately made 

 great advances in the manufacture of stoneware, 

 both for ornamental purposes, and for those of 

 utility only. 



PORCELAIN. 



Porcelain, or china, as it is most frequently 

 called, from the circumstance that our first know- 

 ledge of it was derived from specimens imported 



from China, is a fine compact, hard, and translucent 

 ware, of which there are two distinct varieties. 

 The one is hard the pAte dure of the French 

 potters and the other soft or tender pdte tendre. 

 Strictly speaking, they may be said to consist of 

 silica, alumina, and potash (hard porcelain), and 

 silica, alumina, and soda (soft porcelain). The 

 ingredients, however, vary considerably, according 

 to the skill or requirements of the potter. The 

 glaze used for the hard variety is composed of a 

 glass with an earthy base ; but that for the soft 

 always contains some metallic substance, usually 

 lead. 



Kaolin-clay is the largest ingredient in porcelain 

 ware. It is composed of alumina and silica, and 

 is obtained in large quantities in China, Germany, 

 France, and in the county of Cornwall in England. 

 Kaolin is very friable in the hand, and is with 

 difficulty formed into a paste or dough which will 

 bear to be worked. That found in Cornwall is 

 whiter than the foreign clays, and more unctuous 

 to the touch. It is a decomposed felspar one of 

 the constituent minerals of granite which has 

 accumulated in vast quantities in certain localities, 

 having been no doubt washed down by rains from 

 the weathered and exposed surface of granitic 

 rocks. When the kaolin or china clay of Corn- 

 wall is mixed with alluvial matter, it is broken 

 into lumps, and thrown into a running stream ; 

 this carries off the firm particles into catchpools, 

 where the sediment is allowed to settle, and the 

 water is drawn off, leaving the clay. 



Among recent inventions in the manufacture of 

 porcelain may be mentioned Parian or statuary 

 porcelain, the beauty of which will doubtless be 

 familiar to most of our readers through the 

 medium of the reproductions of modern sculpture, 

 on a reduced scale, by the celebrated firms of 

 Minton & Co. and Messrs Copeland. The use 

 of a soft felspar instead of the Cornish stone, is 

 that which chiefly imparts the peculiar effect. 

 Great care is necessary in producing articles of 

 this material : they are generally cast in moulds, 

 in a number of pieces ; and as the process of firing 

 contracts the size to a considerable extent, great 

 skill on the part of the artist is called for. Un- 

 glazed porcelain has the appearance of marble or 

 alabaster, and is much used for ornamental articles 

 and statuettes. It is known by the name of 

 ' biscuit.' In the adaptation of this material, the 

 Sevres manufactory in France has been long dis- 

 tinguished. The English manufacturers are, how- 

 ever, fast following them, if not already equal 

 Messrs Minton have succeeded in producing 

 specimens of this manufacture, which, for their 

 'freshness of effect and excellent taste,' have 

 attracted great attention. Parian porcelain far 

 exceeds in beauty and softness the ordinary 

 porcelain biscuit ; the effect arises from the light 

 penetrating to a certain depth, while in biscuit 

 the light is reflected at the surface, giving it a 

 ' cold appearance.' 



In painting on porcelain, the same colouring 

 materials are used as those employed in colouring 

 glass or earthenware. In all the more delicate 

 patterns, they are laid on with a camel-hair pencil, 

 and generally previously mixed with a little oil of 

 spike or oil of turpentine. Where several colours 

 are used, they often require various temperatures 

 for their perfection ; in which case, those that bear 

 the highest heat are first applied, and subsequently 



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