402

SODA

Chemically the water of crystallization is partially driven off', though itstill retains above a half of this.

Medicinally it is employed like the preceding in doses of gr. v to 3jmade into pills, which would fall to powder if composed of theundried subcarbonatc, which, however, must be used in making thecompound pills of iron. Soap, or some aromatic powder, may beused in forming the pills,Soiwe Sulphas. L. E. D. P. Sulphate of Soda. Glauber's Salts.Natron vilriolatum. O. Take fcij of the salt which remains afterthe distillation of muriatic acid, Oijss of boiling water; dissolve thesalt in the water, then add gradually as much subcarbonate of sodaas may be required to saturate the acid; evaporate the solution till apellicle appears on the surface, filter it, and set it aside, that crystalsmay form; pour oft" the solution, and dry the crystals on bibulouspaper.

Adulterated with common salt, which may be detected by nitrate ofsilver; by sulphate, &c, of iron, which may be detected by aquaammonia added to the solution ; by prussiate of potass, or tinctureof galls; and by acids and alkalies in excess, which may be detectedby turmeric and litmus paper. None of these adulterations, however,are of much medicinal importance. Dr. John Davy thinks thesulphate of iron may have a tonic effect.

Chemically it contains l.Q'36 parts of soda, 24-64 of sulphuric acid, and58 of water. Mr. Phillips says it is a needless expence to use sub-carbonate of soda instead of lime.

Soluble in cold, but more so in boiling water. It is insoluble in alcohol.By exposure to the air it effloresces and loses all its water of crystal-lization. (Gay-Lussac.)

Incompatible with potass and its subcarbonate; with lime water, andthe muriates of lime, ammonia, and barytes; with the acetate oflead, and the nitrate of silver, and also with ammonia, but not withits subcarbonate ; and with sulphate of potass.

Medicinally it has been employed as an efficient purgative since thetime of Glauber, but has been latterly superseded in some degree bythe sulphate of magnesia. The taste, which is very nauseous andrevolting, may be covered by a little cream of tartar, or lemon-juice.The dose of the effloresced salts in powder is 5iij to Jvj of the crys-tallized salt; in solution double these quantities.Soda Tartarizata. L. Tartarized Soda. Tartras potassa; et soda;.E. P. Tartarus soda; et potassce. D. Rochelle Salts. Sal Rupcllensevel Seignettii. O. Take §xx 0 f subcarbonate of soda, ftij of super-tartrate of potass, Ox of boiling water; dissolve the subcarbonate ofsoda in the water, and add, by degrees, the supertartrate of potass;