402

ELEMENTS OF MATERIA MEDICA.

the whole of the first, and part of the second, precipitate. The hydrogenof the decomposed water, with the sulphur of the sulphuret of potassium,forms hydrosulphuric acid, a portion of which escapes in a gaseous form,while the remainder, reacting on some sesquioxide of antimony, produceswater and sesquisulphuret, which are precipitated along with somewater of the solution. These changes will be better comprehended byreference to the following diagram :—

REAGENTS.

Sulphuric Acid Free Potash

Water .

Water

Antim

r Oxygen ..

Potash

f Hydro&ulphc- Ad. .

^Hydrogen.

{HydrosulphcAd.^sd*.

RESULTS.

Sulphate Potash

HydrosuIph c .Ad. ?asWater .

Sesquisulpt. Antim. ..

Sesquisulpt. Antim. .Sesquiox. Antim. ...

ntim.-Sesqui- C Potassium'/sulphuret Po-\ Sulphur..'tassium-(.Sesquisulphuret of Antimony,

f Potash ....

Uypo-antimomte 1 Sesquiox . Antim . JOxgjen^

C Sesquioxide Antimony

For further details respecting the theory of this process I must refer thestudent to Berzelius’s Traite de Chimie, ii. 501, and Liebig and Poggen-dorf’s Handworterb. d. Chemie , i. 439.

Properties. —Oxysulphuret of antimony, Ph. L. is a bright red, odour-less, almost tasteless powder. It is insoluble in cold water, and onlyslightly soluble in liquor ammonite. Boiled in nitro-hydrochloric acid,chloride of antimony is formed in solution, and some sulphur remains un-dissolved. Heated in the air it bums, evolves sulphurous acid, andleaves a greyish residuum.

Characteristics. —When heated with concentrated hydrochloric acidit evolves hydrosulphuric acid, shewing it to be a sulphuret. From theother sulphurets or oxysulphurets of antimony it is to be distinguishedpartly by its colour. Its hydrochloric solution is shewn to contain anti-mony by the tests before mentioned for the sesquichloride of this metal(vide p. 400.) When boiled in a solution of bitartrate of potash weobtain a solution of emetic tartar, which may be recognized by the cha-racters hereafter to be mentioned for this salt. It may be reduced byhydrogen and heat (vide p. 409.)

Composition. —When boiled in a solution of bitartrate of potash, itloses, according to Mr. Phillips (7Vans. 3d ed. 203), 12 per cent.: theamount of sesquioxide that it contains. Its composition, according tothe same authority, is as follows :— ,

Sesquioxide AntimonySesquisulphuret AntimonyWater.

Eq. Eq.Wt.

1 77 .

, 5 445 .

.8 72 .

Per Cent.

. 13 .. 75 .. 12 .

Phillips.. 12. 76'5

. 11-5

Oxysulphuret Antimony . . . 1 594 . . . 100 . . . lOO'O

But the sesquisulphuret and sesquioxide are probably only mechanicallymixed.

The commercial oxysulphuret is of a brighter colour than that ob-tained according to the process of the Pharmacopoeia . A manufacturerof it informs me it is prepared by boiling sulphur along with the sesqui-sulphuret of antimony and potash, and precipitating by an acid in theusual way.