OXYSULPHURET OF ANTIMONY.

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Antimo'nii 0 xy sulphur e’turn.—Oxysulphuret of Antimony.

Historw —Basil Valentine ( Triumphant Chariot of Antimony , byKirkringius, p. 131) was acquainted with this preparation; and proba-bly also knew the substance called Kermes mineral, though he does notmention it in his writings. Glauber, in 1658, and Lemery, in 1707, areboth said to be discoverers of the latter substance; but it is hardlypossible for Basil Valentine to have been unacquainted with it.

Natural History. —Kermes mineral, which is an oxysulphuret ofantimony, though not identical with, yet nearly allied to, the preparationof the Pharmacopoeia, is found native in Saxony and other places: it iscalled by mineralogists red antimony or native kermes.

Preparation. —If black or sesquisulphuret of antimony be boiled inan alkaline liquid, a solution is obtained which, on cooling, deposits a. reddish powder called kermes mineral. If a dilute mineral acid be added| to the filtered mother liquor, an orange red precipitate is produced, calledthe golden sulphur et of antimony. If the acid be added before the kermeshas deposited, we obtain the orange red precipitate, called in the Phar-macopoeia oxy sulphur et of antimony.

The oxysulphuret of antimony, Ph. L. is prepared by mixing together7 ounces of powdered sesquisulphuret of antimony, 4 pints of solution ofj potash, and 2 gallons of distilled water: boil for two hours, frequentlystirring, distilled water being often added, that it may fill the same mea-sure. Strain the liquor, and gradually drop into it as much sulphuricacid as may be sufficient to throw down the oxysulphuret: then wash awaythe sulphate of potash with water, and dry what remains with a gentleheat.

Theory of the Process. —When sesquisulphuret of antimony andpotash are heated together, the latter gives oxygen to the antimony, andpotassium to the sulphur of the sesquisulphuret; and thus sesquioxide ofantimony and sulphuret of potassium are produced. The sesquioxidecombines with some undecomposed potash, forming hypo-antimonite ofpotash, and the sulphuret of potassium with sesquisulphuret of antimony,forming a double sulphur salt (the antimonio-sesquisulphuret of potas-sium). These changes are explained in the subjoined diagram:—

REAGENTS.

RESULTS.

Sesquisulphuret of {Sulphur

Antimony. \ Antimony..

Sesquisulphuret of Antimony*..

t> , , ( Potassium-

Potash .| Oxygen_

Sulphuret of Potassium

Sesquioxide of Antimony

Potash

1

S

1

Antimonio-sesquisul-phuret of Potassium.

Hypo-antimonite ofPotash.

The solution contains free potash, the antimonio-sesquisulphuret ofpotassium, and part of the hypo-antimonite of potash. There is a dark-red, undissolved residuum (similar to crocus antimonii) composed of hypo-antimonite of potash and oxysulphuret of antimony: this is got rid of byfiltering.

On the addition of sulphuric acid, sulphate of potash is produced bythe combination of the acid with free potash,—with some potash formedby the union of the potassium of the sulphuret with the oxygen of somedecomposed water,—and with the potash of the hypo-antimonite. Bythese changes sesquisulphuret and sesquioxide of antimony are set free :

D D