516

Metallic Preparations. — Iron.

part III.

and at the same time it probably enters into that degree ofcombination with the ammonia, which exists in triple salts,the product being either a muriate of iron and ammonia, or amixed mass of submuriate of ammonia, and submuriate ofiron: some difference, however, takes place when the carbo-nate of iron, ordered by the London College, is employed;for, a portion ofsubcarbonate of ammonia being formed, whichdoes not combine with the iron, the formation of ferrum am-moniatum is limited: and the sublimed product, instead of be-ing wholly composed of this salt, is only a mixture of it withsubcarbonate of ammonia. The strength of the preparationdepends very much on the degree of heat employed, and thequickness of the sublimation.

Qualities. — Muriate of ammonia and iron has an odour,resembling, in some degree, that of saffron, and a styptic taste.It is in crystalline grains of an orange colour; soluble in alco-hol, and deliquescent; on which account this salt requires tobe preserved in very well stopped phials."

Medical properties and uses. — This preparation of iron istonic, emmenagogue, and aperient. It was formerly muchused in epilepsy, hysteria, chlorosis, scrophula, and rickets;but on account of the uncertainty of the preparation it is nowseldom prescribed. The dose is from grs. iij. to grs. xv. giventwice or thrice a day.

Officinal preparation. Tinctura Ferri ammoniati. L.

SUBCARBONAS FERRI PR^EPARATUS. Edin.Prepared Carbonate oj Iron. x

" Let purified filings of iron be frequently moistened withwater, till they fall into rust, which is to be rubbed to pow-der."

Ferri Rubigo. Dub. Bust of iron.

" Take of iron wire, any quantity. Cut it into small pieces,which are to be exposed to the air, and frequently moistenedwith water, until they be converted into rust; let this be rubbedin an iron mortar, and by pouring "water on it, wash over thefinest part of the powder, which is to be dried."

In these processes the iron is oxidized at the expense of thewater which is decomposed, while at the same time carbonicacid is attracted from the atmosphere, and combined with theoxide. The product is a subcarbonate of oxide of iron, forthe quantity of acid is not equivalent to the neutralization ofthe oxide.

According to my experiments, it consists ofS5 parts of oxideof iron, and 15 of carbonic acid ; but these proportions must

' Carhure de her (F.) Rost (G») Ossido curbomto di Ferro (/.) Sudud ul hidud(Arab.) Eerumbo tuppoo (Turn.)