376

FER

bowe\s. Dose, gr. j to v, combined with rhubarb, or some bitter ex-tract. {Form i 72, 87.) If given in solution, the water should be pre-viously boiled, or the oxygen contained in the atmospherical air, whichis diffused through it, will partially convert the salt into an oa'^-sulphat,and render it insoluble. As an external a-tringent it is useful in theaphtha? of children.* Officinal Prep. Mist : Fern comp • L. (K)Pit: Ferri comp : L (J)

FERRUM AMMONIATUM. L. BIurias

Ammonia: et Ferri. E. D.

Ferrum Jlmmoniacale, P.L. 1787. Flores Martiales.

P.L. 1745. Ens Veneris. P.L. 1720.

Qualities. Form, crystalline grains, which deliquesce ; Colour,orange yellow ; Odour, resembling that of saffron ; Taste, styptic. Che-mical Composition. This is very variable ; depending upon the degreeof heat and length of time employed for its preparation. It seemsto be a mixed mass, consisting of sub-muriate of ammonia and sub-muriateof iron, the metal being in the state of red oxide; and. Mr. Phillipsstates that in the London preparation a portion of sub-carbonate of am-monia is necessarily present The same chemist has also shewn that theproportion of Peroxide of iron in 200 grains is not more than threegrains. Its equivalents will be seen in the Medicinal Dynameter. So-lubility, f3j of water dissolves 3iv of it ; it is also very soluble in alco-hol. Incompatible Substances. The Alkalies, end their Carbonates ; Lime-water, and Astringent vegetables. Medicinal Uses. It is tonic, emmena-gogue, and aperient, but it is so uncertain in its composition and effectsthat it is rarely used Officinal Prep : Tinct i Ferri Amman. L. Form -'36,41,95. Impurities. These are indicated by the dull and pale yel-low colour ot the salt ; it may be purified by re-subliming it.

FERRUM TARTARIZATUM. L.

Tartras Potassa; et Ferri. E.

Tartarum Ferri. D.

Qualities. Form, a powder of a brownish green colour ; Odour,none ; Taste, slightly styptic ; it attracts humidity from the atmosphere,but does not deliquesce. Chemical Composition. Mr. Phillips has de-voted much attention to this subject, apd he states that as it is frequentlyprepared, it is a mere mixture of metallic iron with super-tartrate of pot-ass, coloured by oxide of iron ; when however it is made with more care, itappears to be a double salt, consisting of tartrate of potass and tartrate ofiron ; or may it not be one of those combinations which cream of tartarforms with metal, and of which I have spoken under the article Antimo-nium Tartarizatum ? The quantity of peroxide of iron contained in any

* Forge Water, This popular remedy as a lotion for Aphthse and other similardiseases, I am well satisfied possesses considerable efficacy. It may, perhaps, be ne-cessary to state that Forge-water is that in which the Blacksmith has plunged his hotiron, for the purpose of refrigeration. It is to be taken early in the morning, when,all the mechanical impurities having had time to subside, it is beautifully limpid.Upon examining some of this water I found it to contain sulphate of iron. The?ulphuric acid was probablv- derived from the sulphur of the coal;