3io THE POPULAR SCIENCE MONTHLY. 



PORCELAIN AND THE AET OF ITS PRODUCTION. 



By CHAELES LAUTH, 



ADMINISTRATOR OF THE NATIONAL MANUFACTORY AT SEVRES. 



THE uses of porcelain have so multiplied, the employment of that 

 material has become so general, that few rjersons recollect the 

 time, not yet far back, when it was considered an object of luxury, 

 and only delf was within the reach of all. In this paper I shall con- 

 sider, first, the nature of porcelain and the history of its discovery ; 

 next, the principal points in its manufacture ; and, lastly, the different 

 methods of decorating it. 



It is generally understood that porcelain is, as a rule, the resultant, 

 of the action of fire on a certain kind of clay. No one is likely to con- 

 found it with earthenware or delf. While those wares are soft, opaque, 

 and of impure colors, porcelain is always white, is perfectly clear, and 

 is harder than steel. The fundamental distinction between the three 

 wares is that earthenware is obtained by the simple action of fire on 

 common clays ; delfs are earthenwares more or less colored and glazed 

 with a leaden enamel, which is rendered opaque by tin ; while hard 

 porcelain is obtained from a white clay, kaolin, and is enameled with 

 feldspar. 



Kaolin, a natural hydrated silicate of alumina, is absolutely refract- 

 ory and opaque ; it constitutes the resistant part of porcelain. Feld- 

 spars are silicates of alumina and potassa, fusible at a very high tem- 

 perature into a beautiful transparent glass. If, now, we mix a quantity 

 of feldspar with kaolin, cover the mixture with a layer of feldspar, and 

 heat the whole at a very high temperature, the feldspar will melt and 

 communicate to the opaque clay a clearness greater or less according 

 to the quantity of it present, and to the superficial part of it that beau- 

 tiful glaze with which all are familiar. A part of the action in this 

 process is chemical, and consists in the production of a new crystalline 

 silicate formed by a combination of all the substances present. The 

 discovery of porcelain in China is traced back to a high antiquity. 

 The Chinese have certainly made it regularly for at least a thousand 

 years ; many authors fix the discovery at fifteen hundred or eight- 

 een hundred years ago, but no evidence exists to justify our going 

 further back than a thousand years. The first pieces that came to 

 Europe were probably brought by the Venetians at the end of the 

 thirteenth century. Charles VII, King of France, received a present 

 of Chinese porcelains, about the middle of the fifteenth century, from 

 the Sultan of Babylon ; but it was not till the sixteenth century that the 

 importation of these Oriental products by Portuguese and Dutch mer- 

 chants assumed a real importance. The discovery of tender porcelain 

 was made in France toward the end of the seventeenth century, but 



