PORCELAIN

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PORCELAIN. The Chinese porcelain excels other kinds of ware in the delicacy of its texture, and the partial transparency which it exhibits when held against the light. It has beer long known and manufactured b\ the Chinese, but has never been successfully imitated in Europe until within the last century. In China, porcelain is made by the union of two earths, to which they give the name of petuntze and kaolin, the former of which is fusible in the furnace, the latter not. Both these earths are varieties of feldspar, the kaolin being feldspar in a state of decomposition, and which is rendered infusible by having lost the small quantity of potass which originally entered into its composition. The petuntze is "feldspar undecomposed. These earths are reduced to an impalpable powder by processes described in the article Pottery, and intimately blended together. When exposed to a strong heat, the petuntze partially melts, and, enveloping the infusible kaolin, communicates to it a fine semitransparency. The glazing is produced by the petuntze alone, applied in minute powder to the ware after it is dry.European porcelain. Since the nature of the Chinese earths has been understood, materials nearly of the same kind have been found in different parts of Europe, and the manufacture of porcelain has been carried on in several countries, but particularly at Sevres, in France, with great success. The European porcelains, in the elegance and variety of their forms and the beauty of the designs which are executed upon them, excel the manufactures of the Chinese. But the Oriental porcelain has not yet been equalled in hardness, strength, durability, and the permanency of its glaze. Several of the processes which are successfully practised by the Chinese, remain still to be learnt by Europeans. The manufacturers in Saxony are said to have approached most nearly, in their products, to the character of the Asiatic porcelain. The porcelain earths are found in various parts of the U. States, and will doubtless, hereafter, constitute the material of important manufactures. The finer and more costly kinds of porcelain derive their value, not so much from the quality of their material, as from the labor bestowed on their external decoration. When the pieces are separately painted by hand, with devices of different subjects, their value, as bpecimens of art, depends upon the size of the piece, the number and brilliancy of the colors employed, and more especially upon the skill and finish, exhibited by the artist in the design. The manual part of the operation consists in mixing the coloring oxide with a fluid niedium, commonly an essential oil, and applying it with camels' hair pencils. The colors used are the same as those employed in other kinds of enamelling. When one color requires to be laid over another, this is performed by a second operation; and it often happens that a piece of porcelain has to go into the enamel kiln four or five times, when a great variety of colors is contained in the painting. The magic porcelain of the Chinese has figures upon its surface, said to be invisible when the vessels are empty, but becoming apparent when they are filled with water.