Lond. Edin. Sulphate of Soda.

Syn. Sulphate de Soude (F.), Krystallisirtes Schwefelsauress Natrum, Glau-bersalz (G.), Sale mirabile di Glaubero (I.), C'hara Nun, (H).

This salt is found native in combination with oxide of iron, chloride of sodium, and carbonate of soda, and sometimes effloresced on the surface of the soil in the neighbourhood of salt lakes, in Hungary and North America.3 It is also found effloresced in caves near the villa Mulighin, in the Canton of Argavie; and very often forming part of the contents of mineral saline springs, as those of Cheltenham and of Carlsbad. But the greater part of it used in this country is artificially prepared, and chiefly in the large way, during the manufacture of sal ammoniac from sulphate of ammonia and common salt. The London College has a formula also given for its preparation; I shall, therefore, defer the consideration of its qualities and uses till it come under notice among the Preparations.

1 The following appears to be the solubility of chloride of sodium : - 100 parts of water at 13.89° centigrade dissolve 35.81 parts of the chloride.

16.90 35.88

59.93 37.14

109.73 40.38 Ure, Chem. Dict.

2 The purgative property of sea-water does not altogether depend on this salt, as it contains a large proportion of chloride of magnesium, which is purgative.

To the north of Carlton House, on the river Skatchawan, lat. 53° 20', is a small lake, on the shores of which, in the summer time, it effloresces in the form of a fine powder, to the depth of two or three inches. -Franklin's Journey to the Polar Sea, 4to. . 506. Appendix. Captain Hall also relates, that the valley of Copiapo, on the coast of Chili, is covered with a layer of sulphate of soda, several inches thick. The salt looks like, snow upon the ground.-Journ. in South America, vol. ii. p. 22.