Prep. Made by decomposing a solution of the sulphate of iron, by means of carbonate of soda, collecting the precipitated carbonate on a filter, and having first subjected it to expression, rubbing it with sugar in a porcelain mortar, and drying at a temperature not exceeding 212°.

Prop. & Comp. The saccharatcd carbonate of iron consists of carbonate of iron (Fe O, Co2), mixed with peroxide of iron and sugar; the carbonate should form at least 57 per cent. of the mixture. It occurs in small lumps of a grey-brown colour, and a sweet chalybeate taste, and dissolves with effervescence in warm hydrochloric acid diluted with half its volume of water, and this solution is but slightly affected by the ferrocyanide, but gives a copious blue precipitate with the ferrideyanide of potassium, showing that the salt of iron is mostly in the state of protoxide. Its solution in hydrochloric acid gives but a very slight precipitate with chloride of barium.

Twenty grains dissolved in excess of hydrochloric acid and diluted with water continue to give a blue precipitate with the ferrideyanide of potassium, until at least 33 measures of the volumetric solution of bichromate of potash have been added, indicating that 5.6 grains of protoxide are present.

Off. Prep. Mistura Ferri Composita. Compound mixture of Iron. (Powdered myrrh, sixty grains; carbonate of potash, twenty-five grains; rose-water, eight fluid ounces; sulphate of iron, thirty grains; spirit of nutmeg, one fluid drachm; sugar, sixty grains. Rub the myrrh with the spirit of nutmeg and the carbonate of potash: to these, while rubbing, add first the rose-water, with the sugar, then the sulphate. Put the mixture immediately into a glass vessel, and stop it.)

Pilula Ferri Carbonatis. Pill of Carbonate of Iron. (Sac-charated carbonate of iron, one ounce; confection of roses, a quarter of an ounce. [U. S. Recently precipitated Carbonate of Iron made into a pill mass with clarified honey and sugar.] [U. S. Pilulae Ferri Compositae. Compound Pills of Iron. Myrrh, 120 grains; carbonate of soda, sulphate of iron, each sixty grains; made into a mass with syrup and divided into 80 pills.]

Therapeutics. The carbonate of iron in any of the above preparations has the properties of iron before noticed. (See also Part II.) The carbonate is not astringent, and produces little or no action upon the mucous membranes of the alimentary canal. It has enjoyed great repute in the form of mist. ferri comp., or Griffiths's mixture, as it was called, in the treatment of anaemic amenorrhoea.

Dose. Of ferri carbonas saccharata, 5 gr. to 20 gr. or more; of mist, ferri comp., 1 fl. oz. to 2 fl. oz.; of pil. ferri carbonatis, 5 gr. to 20 gr. or more. [Of the compound pills of iron, one or two three times a day.] When the mixture has been kept many days, it becomes reddish-brown in colour, from the green carbonate being converted into the sesquioxide of iron. The sugar in the other two preparations preserves the salt from oxidation.