502 Metallic Preparations. — Antimony. part nr.

into an acid. Sub-sulphate of antimony is then formed bythe action of part of the acid on the protoxide, which has agrayish appearance when washed, and is in a state fit to beacted upon by the tartaric acid of the supertartrate of potash,and form the ternary salt.

The theory of the other two processes is sufficiently ob-vious. The superabundant acid of the supertartrate of pot-ash combines with the oxide of antimony, forming a triple salt,or a tartrate of antimony and potash; which, on the princi-ples of the reformed nomenclature, should be the pharmaceu-tical name of this salt.

It must be regretted that all the Colleges have not concur-red in adopting the same preparation of antimony for the for-mation of this important salt.

Qualities. — Tartrate of antimony and potash is procuredin small rectangular trihedral crystals, of a white colour, in-odorous, nearly insipid, and efflorescent. It should be boughtin crystals; and to ascertain its purity, a few of these shouldbe put into a dilute solution of ammonice sulphuretum, whentheir goodness may be judged of by the quantity of orange-coloured precipitate that forms. It is soluble in about 15parts of water at 60°, and in 2 parts at 212°, forming whenthe salt is good a perfectly clear transparent solution. It isspontaneously decomposed when kept in aqueous solution ;and is also decomposed by heat, the strong acids, the alka-lies and alkaline carbonates, the earths, hydrosulphurets,some of the metals, and by the decoctions or infusions ofmany bitter and astringent vegetables, with which thereforeit ought never to be conjoined in extemporaneous prescription.According to the analysis of Thenard ', its constituents are35-4 of tartaric acid, 39'6 of oxide, 16-7 of potash, and 8'3of water; but these proportions must necessarily vary withthe different modes of preparation.

Medical properties and uses. — This triple salt is emetic,diaphoretic, expectorant, alterative, and rubefacient; and itoperates also sometimes as a cathartic. It is certainly themost important of the antimonial preparations, and whenthe dose is properly apportioned may supersede the use of allthe others. It is given as an emetic in the commencement offevers, in doses of from one to two grains dissolved in dis-tilled water. To obtain its diaphoretic effect, the dose isfrom Tfeth to ^th of a grain; and the same or a smallerdose combined with squill, ammoniacum, and camphor, andrepeated every three hours, operates as an expectorant. Invery minute doses combined with calomel, it is a powerful al-

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1 jinnales de Chimie s xxxvni. 39.