I

h

I

394 Preparations and Composition?:. Part III.

Prussian Pharmacopoeia directs two parts of sulphuret of an-timony, an J one of exsiccated carbonate of soda, to be melt-ed, and afterwards boiled fifteen minutes in six or eight partsof water, which, on cooling, deposites a considerable quantityof kermes. The fluid from which the kermes has been de-positee! may be again boiled in the residuum of the first de-coction, nnd it will dissolve a fresh proportion of kermes;and this process may be repeated as long as there remains anyto dissolve. After this the residuum, when melted, consistsalmost solely of antimony. It therefore seems, that the alkalirenders almost all the sulphur soluble, and only disposes theoxidizement of as much antimony as is capable of combiningwith the sulphuretted hydrogen There appears to be noreason why the whole of the antimony should not be con-verted into kermes, by employing a proper addition of sul-phur and alkali.

Kermes is also made in the humid way. Fourcroy boils,in twenty parts of water, six parts of pure potass of com-merce, and into the boiling solution throws about the twen-tieth part of the weight of the alkali, or 0.3 of a part, of pow-dered sulphuret of antimony, and continues the boiling forseven or eight minutes, then filters, and allows the kermes toprecipitate by cooling. Hermbstadt uses very different pro-portions ; for he boils twelve parts of sulphuret of antimony,and three of salt of tartar, in ninety-six parts of water, downto sixty-four, and then filters, &c. Gren employs four partsof sulphuret of antimony, sixteen of carbonate of potass, andsixty-four of water, and boils for several hours. Gdttlingboils eight parts of sulphuret of antimony, and two of sul-phur, in a sufficient quantity of solution of potass, down toone half.

The precipitated sulphuret of antimony, like the kermes,may be prepared either in the dry or in the moist way. Thelatter mode seems to be the most universally employed on theContinent. Gottling boils two parts of sulphuret of antimony,and three of sulphur, in a sufficient quantity of a recent solu-tion of potass filters the solution, and precipitates with sul-phuric acid, diluted with twelve times its weight of water.The Prussian college use equal parts of sulphuret of antimonyat 1 ■:■ pf sulphur. Wiegleb treats in the same manner twop. rts of sulphuret of antimony with one of sulphur. But tohis proportions it has been objected, that the product re-si >L- kenti-.s more than sulphur auratum. If this objec-tion b jttjt, it must apply, in a still stronger degree, to theformula of the British colleges, in which no sulphur is added.