Class VII with hydrogen gas, to the consistency of a syrup, a little carbonate of lithia precipitates. The liquid, when brought to the consistency of a syrup, is honey yellow. When dried in vacuo, over calcined potash, it is gradually converted into an irregular saline mass, which absorbs moisture from the atmosphere, and dissolves readily in alcohol. When concentrated in the open air it deposites long yellow crystals of quater-sulphuret of lithium. This salt may be obtained by the same process as that described for procuring sulpho-hydrate of potassium.' 5. Sulpho-hydrate of barium. When hydrate of barytes is supersaturated with sulphide of hydrogen, and the solution concentrated in a retort filled with hydrogen gas, it deposites crystals of hydrated barytes and of quater-sulphuret of barium. The residual liquid, when cooled to 14° deposites crystals of sulpho-hydrate of barium in long flat prisms, which are white and opaque.+ When sulphate of barytes is converted into sulphuret, by mixing it with charcoal and keeping it red hot in a crucible, if boiling water be poured upon the black mass, and filtered while hot, the green coloured solution thus obtained yields by evaporation a great number of crystals. They are to be separated immediately by filtration, and dried between the folds of filtering paper. They are white, and have a silky lustre. They have usually the form of scales, whose shape cannot be easily ascertained. This compound is soluble in water, and the solution has a very slight tinge of green. Its taste is acrid and sulphurous; and when exposed to the air it is readily decomposed. 6. Sulpho-hydrate of strontium. This salt may be obtained by saturating an aqueous solution of sulphuret of strontium with sulphide of hydrogen. The solution evaporated in vacuo, shoots into large striated four-sided prisms, which may be exposed for some days to the atmosphere without undergoing any alteration. When heated they melt, give off water and sulphide of hydrogen, and finally sulphuret of strontium remains behind in the form of a white powder.§ 7. Selpho-hydrate of calcium. This salt may be obtained in solution by dissolving sulphuret of calcium in an aqueous solution of sulphide of hydrogen. At a certain degree of saturation the absorption of the sulphide ceases, and to get any farther quantity taken up, constant stirring is necessary. The solution cannot be made to deposite crystals of sulpho-hydrate of calcium, After the concentration has reached a certain point the sulphide is disengaged, and crystals of sulphuret of calcium shoot out.* 8. Sulpho-hydrate of magnesium. This salt may be obtained in solution by passing a current of sulphide of hydrogen through water in which hydrate of magnesia is suspended. The solution takes place slowly; but a very concentrated liquid may in this way be obtained. Like the preceding salt, it cannot be obtained in a solid form, for when we attempt to crystallize the liquid the salt is constantly decomposed.† SECTION II.—OF BISULPHO-CARBONATES. For our knowledge of these salts we are chiefly indebted to Berzelius. Several of them were described in his paper on bisulphide of carbon, published along with Dr. Marcet, in the Philosophical Transactions for 1813. The mistakes into which he fell in that paper were rectified in his paper on the sulphurets of potassium, published in 1821, and still more completely in his paper on the sulphur salts, published in 1825. It is difficult to obtain these salts in a state of complete purity. The best way is to mix a strong sulphur basis with water and bisulphide of carbon in a flask quite filled with the mixture, and to leave it in the temperature of 86° well stopped. The bisulphide gradually combines with the sulphuret. When dry bisulpho-carbonates are heated they undergo decomposition. The fixed alkaline salts fuse into a liquid black mass, which, when cold, is dark brown, and when digested in water leaves carbon undissolved, while the metal in the state of sexsulphuret is dissolved in the water. The bisulpho-carbonates of the earthy metals and the metals in general are decomposed in such a way, that if the salt contains chemically combined water, bisulphide of hydrogen and sulphur are evolved, and a carbonate remains behind. But in general the bisulphide of carbon flies off and leaves the base in the state of a sulphuret. When the bisulpho-carbonates are mixed in the solid form with an acid, muriatic acid for example, a red oily-looking Berzelius, Kong. Vet. Acad. Handl. 1825, p. 215. + Ibid. p. 216. Sect. II. Class VII. liquid is obtained, discovered and described by Zeise. It is a compound of sulphide of hydrogen and bisulphide of carbon. Speedily the sulphide of hydrogen dissolves in the water, and leaves the bisulphide of carbon behind in an opaque state. 1. Bisulpho-carbonate of ammonia. This salt was first formed and described by Zeise. He saturated alcohol with ammoniacal gas and dissolved bisulphide of carbon in the liquid. In about an hour or an hour and a half a yellow crystalline powder was deposited, which, after being washed with alcohol and ether, constitutes the bisulpho-carbonate of ammonia in a state of purity.* 2. Bisulpho-carbonate of potassium. This salt is best prepared by adding an excess of bisulphide of carbon to an alcoholic solution of hepar sulphuris. The dark red liquid which collects at the bottom is to be evaporated in the temperature of 86° to the consistency of a syrup. It then deposites crystals of bisulpho-carbonate, which speedily deliquesce in the air. When heated to about 150° it parts with its water of crystallization and loses its crystalline appearance, acquiring a darker colour inclining to red. When heated in a distilling apparatus it gives out nothing volatile. At a red heat it melts and is decomposed. In alcohol it dissolves with difficulty.† 3. Bisulpho-carbonate of sodium. It forms a yellow salt, crystallizing when highly concentrated, and deliquescing in the air. It dissolves readily in alcohol.‡ 4. Bisulpho-carbonate of lithium. This salt is still more soluble in water than either of the two preceding salts. When dried it gives a salt that speedily deliquesces in the air. It dissolves readily in alcohol. § 5. Bisulpho-carbonate of barium. Crystallized sulphuret of barium unites very readily with bisulphide of carbon, and forms a lemon yellow uncrystallizable salt, which coats the inside of the glass and is easily dissolved. The solution has a fine yellow colour. When evaporated in vacuo it deposites small light yellow translucent crystals. If a drop of water be let fall on the salt it becomes in a few minutes red; but this colour disappears on drying. 6. Bisulpho-carbonate of strontium. It is more soluble in water than the preceding salt. The solution has a lighter *For a detailed account of this salt I refer to Zeise's Schweigger's Jour, xli. 100. paper, inserted in + Berzelius, Kong. Vet. Acad. Handl, 1825, p. 251. ‡ Ibid. || Ibid. p. 252. yellow colour, and gives, when evaporated in vacuo, a striated crystalline salt, of a light lemon yellow colour, as if it had effloresced. When moistened it becomes reddish brown, but this colour vanishes on drying, leaving spots of a lighter yellow.* 7. Bisulpho-carbonate of calcium. This salt gives a very deep red solution, which becomes still darker when kept in a close vessel. By evaporating the liquid in vacuo we obtain a yellowish brown saline mass, with evident marks of crystallization. When fully dried by heat it becomes light lemon yellow; but becomes again darker and redder by absorbing moisture. When again dissolved, it leaves a yellow coloured subsalt having a peppery taste. This salt is always formed unless an excess of bisulphide of carbon is employed. The neutral salt dissolves easily in alcohol. It is decomposed by boiling water, depositing carbonate of lime.+ 8. Bisulpho-carbonate of magnesium. This salt is most easily obtained by adding bisulpho-carbonate of barium to sulphate of magnesia as long as a precipitate continues to fall. The liquid must then be filtered and evaporated in vacuo. The solid salt is lemon yellow, and shows no symptom of crystallization. A portion of it dissolves readily in water, with a deep yellow colour, and a peppery taste. Another portion forms a subsalt, insoluble in cold, but soluble in boiling water, with a light yellow colour. But it is decomposed at the same time, and leaves carbonate of magnesia undissolved.‡ 9. Bisulpho-carbonate of iron. This salt may be obtained by mixing solutions of bisulpho-carbonate of calcium and sulphate of iron. It forms a deep wine red liquid, which gradually darkens, and when viewed by reflected light, looks like ink. An excess of the precipitating medium gives the liquid a darker colour. An excess of the protosalt of iron employed, precipitates the compound in the form of a black powder.§ 10. Bisulpho-carbonate of sesqui-sulphuret of iron. Bisulphocarbonate of calcium, when added to a solution of peroxide of iron, throws down a dark brown precipitate, which speedily collects into a mass. It is insoluble in water, is not altered during drying, and when pulverized, constitutes an amber brown powder. When distilled, bisulphide of carbon passes over at a very moderate heat. When the heat is augmented, sulphur sublimes, and sulphuret of iron remains. || * Berzelius, Kong. Vet. Acad. Handl. 1825, p. 252. + Ibid. || Ibid. p. 235. Sect. II. Class VII. 11. Bisulpho-carbonate of manganese. It may be formed in a dark the same way as the two preceding salts. It forms first brown transparent liquid; but gradually the salt is deposited in a light yellow powder, like sulphuret of manganese. This precipitate dissolves with a yellow colour. It does not blacken on the filter like sulphuret of manganese. When distilled, it gives out carbonic acid gas and sulphur, and leaves green sulphuret of manganese soluble in muriatic acid, without any residue of charcoal.* 12. Bisulpho-carbonate of nickel. Formed by the same process as the preceding salts. It forms a deep brownish yellow solution, slightly translucent, and by reflected light, black. The salt falls in 24 hours in the form of a black powder. The supernatant liquid is transparent and yellow.† 13. Bisulpho-carbonate of cobalt. Formation the same. Gives a deep olive green solution, which seen by reflected light is black. In 24 hours it deposites a black flocky substance. The neutral liquid is transparent, and of a deep brown colour.I 14. Bisulpho-carbonate of zinc.§ Forms a very light yellow precipitate, indeed almost white, which when dry is yellow and translucent.|| 15. Bisulpho-carbonate of cadmium. A fine lemon yellow precipitate, which is soluble in water.¶ 16. Bisulpho-carbonate of lead. A deep brown precipitate, which, when it is deposited on the glass, appears transparent. The supernatant liquid is deep yellow; but in 24 hours it becomes colourless. The precipitate when dried becomes black, assumes a polish when rubbed, and when distilled gives out bisulphide of carbon, and leaves sulphuret of lead.** 17. Bisulpho-carbonate of tin. Forms a fine dark brown precipitate, not altered when dried.++ 18. Bisulpho-carbonate of bisulphuret of tin. A light yellow precipitate, which becomes deeper coloured when dry.‡‡ 19. Bisulpho-carbonate of copper. A deep brown precipitate, almost black, soluble with a dark brown colour in an excess of the precipitating medium. When dry, it becomes Berzelius, Kong. Vet. Acad. Handl. 1825, p. 254. + Ibid. p. 255. All the subsequent salts may be obtained by the same process as that described for procuring bisulpho-carbonate of iron. Berzelius, Kong. Vet. Acad. Handl. 1825, p. 255. ** Ibid. p. 256. tt Ibid. Ibid. Ibid. |