THE POTTER'S AET. 



if indeed it be possible, to ascertain what are the genuine works 

 of the great artist, and to distinguish them from those of his 

 family, some of whom worked under and with him during his 

 lifetime. 



The productions of this family of artistic potters are formed of 

 a paste, consisting of about 50 per cent, of silica, combined with 

 15 per cent., of alumina and 22^ per cent, of lime, with small 

 proportions of carbonic acid, magnesia, and iron. The decorations 

 were figures in relief, variously coloured with yellow, produced 

 by lead and antimony, a dark opaque blue, the green produced 

 by copper, and a bad violet produced by manganese. The art 

 of producing colours by means of gold was not then known in 

 Europe. 



8. In fig. 22 is represented an altar-screen by Lucca della Robbia. 

 This consists of four pieces and two pilasters. The ground is a 

 fine azure blue; the figures are white; the fruits, cup, &c., in 

 gold-yellow, and the garlands green. The thickness of the 

 earthen ware or faienfe, of which it is composed, is little more 

 than an inch and an half. This piece is preserved in the Cabinet 

 SATJVAGEOT. 



9. The paste used at this epoch not having the whiteness of the 

 finer porcelain, the articles fabricated were covered with an 

 opaque glaze of some particular colours, by which the coarse and 

 ill-coloured ground of the porcelain was concealed. The process 

 by which these opaque glazes were produced was nearly the same 

 as that by which the transparent and colourless glazes of the 

 present day are produced. The baked article, which before it is 

 glazed is called biscuit, is submerged in a vessel containing the 

 verifiable matter, mixed with such a proportion of water as to give 

 it a creamy consistency. After immersion, a coating of this 

 liquid adheres to the surface. The water which holds the vitri- 

 fiable substance in suspension is partly imbibed by the material of 

 the vessel. The vessel, thus coated, is placed in an oven, and 

 again exposed to the action of heat of sufficient intensity to vitrify 

 the coating with which it is invested, so that, when withdrawn 

 from the oven, the coating is converted into a coloured and opaque 

 glass, and the vessel is glazed. Sometimes the article, before 

 being baked, was covered with a coat of earthy matter, not 

 vitrifiable but opaque, by which the coarse surface of the paste was 

 concealed, and this coat being hardened in the oven, a transparent 

 glaze was put over it. 



10. The majolica ware of Italy was in its most flourishing state 

 from 1540 to 1560. It was during this interval that the finest 

 table-services were produced. The chief places of its fabrication 

 were Castel Durante and Florence; but its celebrity and the 



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