Prep. The hydrated peroxide recently precipitated from the solution of the persulphate by means of ammonia is dissolved in a solution of citric acid by the aid of heat, the liquid neutralized by the addition of ammonia, and then evaporated to dryness in thin layers on flat porcelain or glass plates.

Prop. & Comp. It is not crystalline, but dries in garnet or hyacinth-red transparent scales; soluble in water, and forming a neutral solution of a sweet and very light styptic taste. When incinerated with exposure to air it leaves 26.5 per cent. of peroxide of iron; heated with solution of soda, it evolves ammonia; when acidulated with hydrochloric acid it gives a copious precipitate with ferrocyanide of potassium, but none with the ferrid-cyanide. Its composition is not well known; it contains, however, citrate of iron and ammonia: probable formula (Fe2 O3, Nh4 O, HO, C12H5O11+ 2HO).

Therapeutics. As a blood-restorer it is a very effectual salt, and it possesses scarcely any astringency; it may often be given when the stomach will not bear the more styptic preparations of iron.

Dose. 5 gr. and upwards.

Incompatibles. Tannin solutions strike black; caustic alkalies precipitate the oxide.

[Ferri et Ammoniae Sulphas. Sulphate of Iron and Ammonia. Ammonio Ferric Alum. U. S. Made by adding sulphate of ammonia to solution of tersulphate of iron and crystallizing.

In beautiful violet-tinted crystals. A good astringent and used as such in doses of from 3 to 6 grains.]

[Ferri et Ammonias Tartras. Tartrate of Iron and Ammonia. U. S. Prepared by adding recently precipitated hydrated peroxide of iron to a solution of bitartrate of ammonia, and evaporating. It occurs in transparent garnet-red scales of a saccharine taste, and very soluble in water. It has little or no astringency, and may be given in doses of from 5 to 10 grains.]