Carbonate of

Carbonate „ „ = 44.5 „ Chloride „ 9.0 „ = 3•0 99 Organic matter .. „ = 50'0 9, 300.0 „ = „ The potash salts, of course, are derived in the first instance from the soil upon which the food of the sheep is grown, and upon the nature of this soil depends the composition of the " euint." Other things being equal, it has been fouud that the merino wool contains the greatest amount of potassium salts, ranging as high as 30 per cent.

The process usually employed for the extraction of the potassium salts is that of MM. Maumend and Rogelet, and depends upon the ready solubility of the *mint in water. The wool is pressed into casks and thoroughly washed with cold water. The grease of the wool forms, with a certain amount of lime, &c., always present, an insoluble soap, and the suint comes off remarkably freely, iu the shape of a light brown solution, of about 1.15 specific gravity. This is boiled down to dryness, and treated as an ordinary potash liquor, calcined, lixiviated, and again furnaced in a reverberatory furnace. By this method, and by fishing out the chloride and sulphate of potash during evaporation, a very good carbonate is made. This process is carried to a considerable extent in France and Germany ; Rheims, Elbceuf, and Verviers being the chief seats of the trade.

Carbonate of Potash from Felspar, &e.—It has already been noted that the silicates as a source of potassium carbonate form a comparatively untried ground. Many processes have been set on foot for the treatment of these minerals, but very little has yet been done with them on a manufacturing scale. The reader is referred for further information to the patents of Fuchs, Lawrence, Meyer, Ward, Tilghmann, and Sprengel. Most of these processes go upon the same lines—a calcination of the mineral with lime, and lixiviation of the product. Ward adds fluor-spar to the lime to assist in the decomposition of the silicate at the lowest possible temperature, thereby effecting a great saving in time and fuel. This seems to be the beat process yet brought forward.

Carbonate of potash is used largely in the manufacture of soft soaps, being first converted into caustic potash. It is, for all purposes, the principal source whence the hydrate is obtained ; and from it, too, are made the biehromate and yellow prussiate of potash, and various kinds of potash glass. In medicine, it furnishes an antacid and diuretic. It is also largely used for cleans ing purposes; in Turkey red dyeing, for the emulsion of oil, and in printing, as a solvent of annatto, &C.

The only true means of determining the composition of any given sample is to make a com plete analysis. The certain presence of soda compounds renders the ordinary alkalimetrical test of no use, inasmuch as the soda neutralizes the acid along with the potash.

Bicarbonate of Potassium. (FR., Bicarbonate de Potasse ; GER., Zweifach Kohlensaures Synonyms, acid carbonate of potash ; potassium hydrocarbonate. Formula, salt is of comparatively small importance to the manufacturing world. It is, however, used in certain medicinal preparations as a diuretic and antacid. It is usually met with in the form of large crystals derived from a right rhombic prism. Soluble in four parts of cold water, the aqueous solution has a slightly alkaline reaction and taste. Upon boiling, carbon dioxide is given off., and the mono carbonate left. The following table shows the solubility of the salt in water of different temperatures : At 0°, 100 parts of water dissolve .. 19.61 parts.

„ 10 23.33 „ „ 20 99 ,, 26.91 „ „ 50 .. 37.92 „ „ 60 75 • .. „ „ 70 99 75 .. 45.24 „ The crystals, like the solution, are decomposable by heat into carbon dioxide and simple carbonate.

Bicarbonate of potash is usually prepared by passing a stream of carbon dioxide into a cold saturated solution of the carbonate. The gas is rapidly absorbed, forming a white crystalline precipitate of bicarbonate, width is redissolved in hot water, or by passing in steam, and leaving the solution to cool. The bicarbonate separates out in large crystals, which are drained and dried lit a low heat. Another method of producing a very pure salt is to pass a stream of carbon dioxide, prepared from marble aud a pure aeid, into an alcoholic solution of pure caustic potash. Tho crystals of bicarbonate should be washed with fresh alcohol.

Morale of Pntassium. (Fa., Chlorate de Putasse ; GER., Chlorsaures Kali.) Formula, KC103.— This salt has become of considerable importance from a manufacturing point of view. It forms anhydiciu4, tabular crystals, in taste resembling saltpetre, which melt and decompose low red heat, oxygeu being disengaged from both acid and base, and chloride of potassium left. Heated with any combustible matter, chlerate of potash deflagrates violently, explosion often oeeurring with friction, or blows. It is slightly soluble in cold water, the rate of solubility increasing very rapidly as the temperature is raised. Thus:— At 0°, 100 parts of water dissolve .. 3.33 parts of ehlorate.