SODA-ASH. 97 



determinations of spec. grav. and composition, and partly from 

 calculation. The 1st column, A, represents Baume's areometric 

 degrees ; the 2d, B, contains the specific gravity ; the 3d, C, 

 the percentage of oil of vitriol, and the 4th, D, the percentage 

 of the anhydrous acid. (66° B. corresponds to spec. grav. 

 1.842). (An. de Ch. Phys. (3) xxiv. and xxvi.) 



R. A. Tilghman, of Philadelphia, has patented several pro- 

 cesses connected with salines, which possess the high merits 

 of ingenious invention, simplicity of material and action, and 

 the highest prospect of success. One of these processes is 

 for obtaining sulphuric acid by the action of steam on the 

 sulphates of baryta, strontia, or lime, at a high temperature. 

 We refer for minutise to Rep. Pat. Inv. 1847. See also the 

 soda manufacture. 



Crystallized Sulphurous Acid. — Pierre (Comptes Rendus, 

 1848) obtained sulphurous acid in crystals, by passing the gas, 

 previously washed, into water already surcharged with it. The 

 temperature must not exceed 32°. In a few hours several 

 hundred grains will have deposited. Its formula is S03,9H0. 

 Dopping's acid, similarly obtained, has the composition (Bui. 

 de St. Petersbourg, vii.) SOgjHO. 



3. Common Salt and its derivative Arts. — Beside its use as 

 salt (for preserving animal matter, &c.), common salt is largely 

 employed in the preparation of carbonate of soda (soda-ash), 

 according to the invaluable process of Leblanc, by which mu- 

 riatic acid is obtained at the same time. The soda manufacture 

 is therefore most conveniently arranged under these two heads, 

 making soda with its derived salts, and muriatic acid with its 

 derivative arts. Salt is obtained from solid rock-salt forma- 

 tions, by evaporation of salt-springs or brines, or of the 

 waters of the ocean. There is a locality of solid salt found 

 in the United States, in the south-western part of Virginia ; 

 but all the salt used is either imported from Europe or obtained 

 from brines. In making soda-ash, the salt is first converted into 

 sulphate of soda by sulphuric acid, whereby muriatic acid gas 

 is given off, and the salt-cake (dry sulphate of soda), mixed 

 with carbon and carbonate of lime, is heated and extracted 

 I 7 



