Prep. By dissolving iron wire in nitric acid and diluting to the proper strength. One ounce of iron wire with three fluid ounces of nitric acid are used in preparing thirty ounces of the solution.

Prop. & Comp. A clear solution of reddish-brown colour, slightly acid and astringent to the taste. It contains the pernitrate of iron (Fe2 O3, 3 No5) in solution in water. It gives a precipitate with the ferrocyanide, but not with the ferridcyanide of potassium. When to a little of it in a test tube half its volume of pure sulphuric acid is added, and then a solution of sulphate of iron is poured in, the whole assumes a dark-brown colour, show* ing the presence of nitric acid in the solution. Sp. gr. 1.107. [1.106 to 1.107. U. S.] One fluid drachm precipitated with am-monia yields 2.6 grains of peroxide, corresponding to 7.865 grains of pernitrate of iron.

Therapeutics. A powerful astringent tonic, and useful in the same cases as the perchloride. It has been much used in Dublin, and is recommended in some forms of diarrhoea in debilitated subjects, and in passive mucous discharges.

Dose. 30 min. to 1 fl. drm.