GLAUBER’S SALT the popular term for neutral sulphate of sodium (Na 2 SO 4 ), discovered by the chemist whose name it bears, and formerly known as “sal mirabile Glauberi.” It occurs in nature in combination with calcium sulphate as the mineral glauberite, and uncombined in right rhombic prisms, as thenardite, being found in this form in Bolivia and Peru, and near Madrid; or in monoclinic prisms, with ten molecules of water as glauberite or ordinary Glauber’s salt, in Austria, Hungary, Italy, and in great quantity as a deposit from the hot springs of Carlsbad. It is also a constituent of sea-water, and the chief active principle of medicinal waters, and occurs in minute traces in the blood. It has a bitter but not acrid taste. It is somewhat anomalous in its solubility, the maximum occurring at about 34° C. According to Löwel, it exists in aqueous solution at temperatures as high as 34° C. as a decahydrate, but above that temperature as an anhydride, the solubility of the former increasing, and of the latter decreasing, with a a rise of temperature (see Chemistry, vol. v. p. 505). Under ordinary circumstances it crystallizes from solution in large colourless prisms; these, when exposed to the air or heated, effloresce, giving a white powder, which melts at a strong red heat, and on cooling forms a transparent mass. The salt has also been the subject of some interesting experiments made by Guthrie, who at-7° C. procured it in combination with 166 molecules of water. From his investigation of this and other substances, he concluded that the solution of a solid body consists in the formation of a liquid hydrate which ultimately diffuses into the rest of the solvent. In the manufacture of sodium carbonate from salt and sulphuric acid, this sulphate is prepared in ...