Origin.—Sodium hyposulphite is prepared by dissolving sulphur in boiling aqueous solution of sodium sulphite.

Properties.—Colorless, transparent, monoclinic prisms; odorless and having a cooling, afterwards bitter taste. Permanent in air 91.4° F., but efflorescent in dry air above that temperature; slightly deliquescent in moist air. Soluble in about 0.35 parts of water at 77° F. At boiling heat the solution is rapidly decomposed; insoluble in alcohol, slightly soluble in turpentine.

Actions.—Sodium hyposulphite is an antiseptic, deodoriser and insecticide. In the presence of acids, without and also within the body, it gives off sulphurous acid, which it therefore resembles. It is thought to destroy ferments and bacteria, and removes offensive smells. Its properties are greatly increased when used along with the tar acids. When standing long in contact with water the sulphite decomposes and gives off hydrogen sulphide.

Uses.—Sodium hyposulphite is recommended in indigestion, fermentation, flatulence and foul smelling feces and in general septic conditions, but have proven as useless as most other medicines in their latter stages. It is used externally in parasitic affections of the skin and mouth in the form of an ointment or solution.

Doses.—Horses and cattle, ¹/₂ to 1¹/₂ ozs.; sheep and pigs, ¹/₂ to 1 dr.; dogs, 5 to 30 gr.