Iron filings, procured from the common work-shops, may be cleansed from earthy matters or fragments of other metallic bodies, by means of a magnet, though not so perfectly as could be wished. When other metals have been previously melted with the iron, the filings of the compound cannot thus be separated from those of pure iron, the loadstone attracting both: regulus of antimony is the only exception, this metal being found, even in a small proportion, to destroy the magnetic power of the iron.

(a) Differtatio episiolaris de variol. confluent. & affect. hysteric. Oper, p. 409.

Ferri lima-tura purifi-cata Ph. Ed.

The silings are sometimes candied with sugar; a preparation which is very commodious for taking, but which requires a good deal of ad-drefs in the operator, and is made chiefly by the confectioners. Two parts of fine sugar, dissol-ved in water and boiled down to a candy consistence, are added, by little and little, to one part of the cleansed silings, in a kettle suspended over a very gentle fire; and the vessel continually shaken, that the filings may be crusted over with the sugar: to render the matter les subjecl: to run into lumps, a little starch is previously mixed with the sugar, in the proportion of a dram to a pound.

The filings, moistened with vinegar or water, and exposed to a moist air, or occasionally moistened afresh, soon change in great part into rust, which may be separated from the uncor-roded part, by grinding and washing over the finer powder with water. The rust is given in the same dose as the crude filings, and is perhaps rather easier of solution. Hoffman says, he has often used it, with remarkable success, in obstinate chlorotic cases accompanied with ex-ceftive head-achs and other alarming symptoms; and that he usually joined with it pimpinella, arum root, and salt of tartar, with a little cinnamon and sugar.

A piece of steel, heated in a very fierce fire, as that of a smith's forge, to a strong white heat, and immediately applied to a roll of brim-ftone held over a vessel of water, is in part corroded by the sulphur, and melting, falls down in brown coloured drops; which, picked out from the yellow strings of sulphur, and levigated into an impalpable powder, are given in the same doles as the filings and rust, and nearly with the same effects.

Ferri rubigo, vulgo ferri limatura prae-parata Ph. Ed.

Ferri rubigo Ph. Lond.

As this process is somewhat troublesome and accompanied with offensive fumes, the shops have been generally supplied with a sulphurated preparation made more commodiously, by mixing iron filings with twice their weight of flowers of brimstone, and as much water as will make them into a paste, which on standing at reft for some hours swells up, and is then pulverized, put into a heated crucible to deflagrate, and kept constantly stirring with an iron spatula till it falls into a deep black powder.

This powder, urged longer in the fire, becomes red, and in this state has been usually distinguished in the shops by the name of aperient crocus: when further reverberated with a very intense heat, it is called astringent crocus. This notion, of opposite virtues in the two preparations, does not appear to have any just foundation; chalybeate medicines in general acting by an astringent power, though with different degrees of force. The college of Edinburgh allows colcothar of vitriol as a sub-stitute both to the aperient and the astringent crocus; and indeed it appears to be at bottom, if duly prepared, the very same thing with them: all the three are no other than iron, that has been corroded by the sulphureous or vitriolic acid, and afterwards by fire divested of great-eft part of the acid, and reduced to a state of calx: the colcothar, however, as remaining after the distillation of the vitriol, commonly retains much more acid than the others, a circum-stance to be attended to in the substitution of it. In all these kinds of preparations, only a small quantity of the metal is in a soluble or active state, more or less according to the proportion of acid: when iron is perfectly calcined, and no acid combined with it, it has scarcely any fensible operation.

Colcothar Vitrioli Ph. Ed.

Oil of vitriol, diluted with from equal to five or six times its measure, or more, of water, and assisted by a gentle heat, acts readily on iron, and emits, during its action, a strong sulphureous vapour, which on the approach of any flaming body, catches fire, and explodes, so as sometimes to burst the vessel, especially if its mouth is narrow. The solution filtered, and evaporated till a pellicle appears on the surface, yields, on standing in the cold, green crystals, the same with the common green vitriol. To four parts of oil of vitriol some direct three of the iron filings †; others an equal quantity of each ‡.

The marine acid dissolves much less of this metal than the vitriolic: on macerating half a pound of iron filings in three pounds of spirit of salt till the acid ceases to act, a notable quantity remains at last undissolved. The solution is excessively styptic, far more so than the combinations of iron with any other acid: it has likewise this peculiarity, that it mingles equally with, and when infpiffated dissolves in, rectified spirit of wine; on which foundation the spiri-tuous chalybeate tinctures depend. Some in-fpiffate the marine solution, made in the quantity above-mentioned, but with the rust instead of the filings of iron, to the weight of a pound, and then add three pints of rectified spirit: others dissolve three ounces of clean iron scales in a sufficient quantity of the acid, and then add so much rectified spirit as to make the weight of the whole, two pounds and a half.

† Vitriolum martis, feu fal chalybis Ph. Ed.

‡ Ferrum vitriolat. Ph. Lond.

Tinct. ferri muriati Ph. Lond.

Tinct. mar-tis Ph. Ed.

Of these tinctures, a few drops are a sufficient dole..

On grinding iron filings, or washed colco-thar of green vitriol, with equal or twice their weight of sal ammoniac, moistening the mixture with water, gently drying it, and repeating the pulverization, humectation, and exsiccation, a few times; the iron is in a considerable degree attenuated, and on sublimation with a quick fire, so much of it arises with the sait as to communicate a deep yellow or orange colour. If the iron and sal ammoniac be only mixed together, and the sublimation performed with a flow fire, such as a glass retort will bear, the flowers prove at first pale, and require, in order to their being sufficiently tinged with the metal, to be ground with the residuum, sublimed again, and this process repeated. These flowers have a very pungent austere taste, and are supposed to be more aperient and attenuating than the other chalybeates, by virtue of the faline matter joined to the iron. They are moil conveniently given in the form of a bolus, from three or four grains to twenty: they occa-fion pills to swell and crumble, except such as are composed of gummy resins: in a liquid form they are nauseous, except in spirituous tinctures. A tincture made by digesting four ounces of the flowers in a pint of proof spirit, is a sufficiently elegant chalybeate, and may be given in doses of a tea-spoonful.

The matter which remains after the sublimation of the flowers, exposed to a moist air, runs into a liquid, in taste extremely styptic, and greatly resembling a. saturated solution of iron made in spirit of salt; the marine acid and volatile alkali of the sal ammoniac being in part separated from one another in the process.

Flores mar-tiales vulgo Ens Veneris Ph. Ed.

Ferrum ammoniac. Ph. Lond.

Lixivium martis.

Solutions of iron in vegetable acids are much more mild, and less ungrateful both to the palate and stomach, than such as are made in the acids of the mineral kingdom. Vinegar, juices of oranges, lemons, apples, and other fruits, acidulous wines, and tartar, have been made use of for this purpose. A vinous tincture is prepared in the shops, by macerating four ounces of iron filings, for a month, in four pints of mountain wine. The dose of the tincture is from a tea-spoonful to a common fpoon-ful and upwards. For making these kinds of preparations, fine iron wire, cut in pieces, is more eligible than the filings, as we may always depend on the wire being pure iron, and as, by lying looser, and exposing a larger surface to the fluid, it is more easily acted on.

Some direct solutions of iron made in wine, or other vegetable acids, to be infpiffated to the consistence of an extract. These kinds of preparations are commodious for some purposes, particularly for being made into pills; as being tenacious enough to give a due consistence to a considerable admixture of powdery matters. They are most of them very apt to grow mouldy in keeping; an extract made with the juice of golden rennets is said by Neumann to be free from this inconvenience.

A combination of iron with the acid of tartar is most commodioufly obtained, by grinding the filings with equal their weight of cryslals of tartar, forming the mixture into a mass with water, then pulverizing, and repeating the humectation and exficcation alternately, till the whole falls into an impalpable powder. The London college direct double the weight of cryftals of tartar; and order the mixture, after exposure to the air in a shallow earthen vessel for eight days, to be dried and ground to an impalpable powder. This is a very elegant and useful chalybeate, the tartar rendering almost all the iron dissoluble. It is given either in a solid or liquid form, from two or three grains, to ten or more. It has been usually distinguished in the shops by the name of its inventor Dr. Willis.

Vin. ferri Ph. Lond.

Extract. mart.

Mars folub. feu chalybs tartarizatus.

Ferrum tar-tarifat. Ph. Lond.

If the mixture of iron filings and tartar be calcined in a crucible for some time with a red heat, and such part as cannot easily be reduced into fine powder, calcined again; the tartar will be converted into a fixt alkaline salt, and by chis alfo the iron will be in part corroded and rendered soluble. There are several other methods of obtaining alkaline solutions of iron; but these kinds of combinations appear ill adapted for medicinal use, and are at present wholly neglected.

Some have made trial of the blue precipitate of iron called Prussian blue, and report that it seemed to act as a diaphoretic, and in some cases as an aperient (a). Of all the known preparations of iron, this promises the least activity: the perfect calces, almost if not wholly inert, are soluble in certain acids, particularly in the marine; but the Prussian blue is not acted upon by any kind of acid menstruum.