CHINA
The material employed in the manufacture of Chinese porcelain is composed of two ingredients, petuntse and kaolin. Of these the former is fusible and gives to the ware that transparency which characterises true porcelain; the other is infusible, and its presence enables the mass to support the temperature necessary to transform the fusible element into glass. Both are found in the mountains of a district distant about sixty miles from Ching-tê-chên, whither they are brought by boat, having first undergone preliminary manipulation and been reduced to the form of bricks. M. Salvétat's analysis shows that these materials practically correspond in all their constituents with those drawn from the mines at Saint-Yrieix and used at the Sèvres factories. At Ching-tê-chên the bricks undergo further treatment, which need not be described here since it presents no novel or noteworthy features. The kaolin and the petuntse are then mixed—in equal portions for the finest porcelain; in the ratio of four parts of kaolin to six of petuntse for middle-class ware; and in the ratio of one part of kaolin to three of petuntse for inferior ware. M. Salvétat has analysed the masses of four qualities of Chinese porcelain. His results, side by side with corresponding figures for the Sèvres pâte, are as follows:—
| Chinese Porcelains. | |||||
| Sèvres Porce- lain. | |||||
| First Quality. |
Second Quality. |
Third Quality. |
Fourth Quality. | ||
| Silica | 69.0 | 70.0 | 73.3 | 69.0 | 58.0 |
| Alumina | 23.6 | 22.2 | 19.3 | 21.3 | 34.5 |
| Iron Oxide | 1.2 | 1.3 | 2.0 | 3.4 | 34.5 |
| Lime | 0.3 | 0.8 | 0.6 | 1.1 | 4.5 |
| Magnesia | 0.2 | trace | 0.6 | 1.1 | 4.5 |
| Manganese Oxide, | 0.1 | trace | 0.6 | 1.1 | 4.5 |
| Potash | 3.3 | 3.6 | 2.5 | 3.4 | 3.0 |
| Soda | 2.9 | 2.7 | 2.3 | 1.8 | 3.0 |
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