24. New Double Chromates.
Chromate of potash and sulphate of nickel were mixed in atomic proportions, and the solutions heated; after the chromate of nickel was separated, they were evaporated to dryness. The residuum, digested in water, was filtered, and the deep red solution obtained upon cooling, yielded grass green crystals in the form of oblique rhombic prisms; 50 grains of these, when analysed, gave 12.26 sulphuric acid; 0.978 chromic acid; 8.2 oxide of nickel; 9.862 potash; 12.7 water.
A similar salt may be obtained by mixing chromate of potash and sulphate of copper. It is of a light green colour, and has precisely the same form as the salts already described. In every case crystals of bichromate of potash were produced in the second crop crystals.—Phil. Mag. N. S. ii. 427.
25. Dobereiner’s finely divided Platina.
26. New Metals.
27. Analysis of Porcelain, Pottery, &c., by M. Berthier.
| PORCELAIN. | |||||||
|---|---|---|---|---|---|---|---|
| Sèvres. (i.) | English. (ii.) | Piedmont. (iii.) | Tournay. (iv.) | ||||
| Silica | 0.596 | 0.770 | 0.600 | 0.753 | |||
| Alumina | 0.350 | 0.086 | 0.090 | 0.082 | |||
| Potash | 0.018 | . . | . . | 0.059 | |||
| Soda | . . | . . | . . | 0.059 | |||
| Lime | 0.024 | 0.012 | 0.016 | 0.100 | |||
| Magnesia | 0.070 | 0.152 | . . | ||||
| Water | 0.008 | 0.056 | 0.136 | 0.006 | |||
| 0.996 | 0.994 | 0.994 | 1.000 | ||||
(i.) Sèvres service—Paste strongly heated. It is formed from 0.63 washed kaolin of Limoges; 0.105 quartz sand; 0.052 Bougeval chalk; 0.21 of the fine sand obtained from kaolin by washing, and which is a mixture of quartz and felspar. The glaze of this ware is made of a rock composed of quartz and feldspar. When reduced to a fine powder, it is found to be composed of silica .730, alumine 162, potash 84, water 6: it fuses into a perfectly transparent and colourless glass.
(ii.) Worcester porcelain—Paste taken from the workshops, unbaked.
(iii.) Porcelain of Piedmont—Paste dried. The base of this manufacture is the magnesite of Baldissero.