Ammonia lithium sulphate, water

Note. — For equilibrium between lithium sulphate ammonia and water, see Schreinemaker and Cochert — Chem. Weekblad. 2, 771 3,... 

Precipitate with aq. ammonia. Evaporate the soln. down to about 100 c.c., and filter the ot liquid so as to remove calcium sulphate. The cone. soln. is sat. with ammonium alum and allowed to stand for some time. The mixed crystals of potassium, rubidium, and oeesium alums and of lithium salt are dissolved in 100 c.c. of distilled water and recrystal-lized. The recrystallization is repeated until the crystals show no spectroscopic reaction for potassium or lithium. The yield naturally depends on the variety of lepidolite employed. 100. grms of an average sample gives about 10 grms. of crude crystals and about 3 grms. of the purified caesium and rubidium alums. For the purification of caesium and rubidium salts, see the chlorides. The mother-liquors are treated with an excess of barium carbonate, boiled, and filtered. The filtrate is acidified with hydrochloric acid, and evaporated to dryness. The residue is extracted with absolute alcohol in which lithium chloride is soluble, and the other alkali chlorides are sparingly soluble. 

According to F. C. Franklin and C. A. Kraus,40 liquid ammonia readily dissolves sodium and potassium iodides. The partial press, of ammonia in soln. of potassium iodide at 25°, as measured by R. Abegg and H. Riesenfeld, is raised from 13 45 mm. of water to 13 28, and 14 88 mm. for 0 5W-, N-, and l 5Ar-soln. respectively. H. M. Dawson and J. McCrae have shown that the distribution of ammonia between water and chloroform is generally lowered by the addition of various salts of the alkali metals and ammonium which they tried—halides, nitrates, chlorates, oxalates, sulphates, carbonates, hydroxides this means that the solvent power of aq. soln. of the alkali salts is in general less than that of pure water—lithium chloride, ammonium bromide, and sodium iodide act in the opposite way. The other halide salts of lithium were not tried. The change produced in the partition coeff. by the halides, at 20°, is as follows ... 

This alkali can only be obtained from either of the above minerals, which are silicates. One part of the mineral in fine powder is mixed with two of fluor-spar, and the mixture heated with sulphuric acid, until the whole of the silica is dissipated. There then remains a mixture of sulphates of alumina, lime, and lithia, and, in the case of lepidolite or spodumene, potash. By boiling with carbonate of ammonia in excess, the alumina and lime are precipitated, and the filtered liquid is evaporated to dryness, and ignited to expel the sulphate of ammonia. The residue is sulphate of lithra, or sulphates of lithia and potash. In the latter case, by the cautious addition of chloride of barium, the sulphuric acid is separated as sulphate of baryta, and the lithia and potash converted into chlorides. These being dried, are digested in absolute alcohol, which dissolves the chloride of lithium. The lithia is now free from other bases to obtain it in the separate state, the chloride is converted into sulphate, by being boiled with oil of vitriol, and the solution of the sulphate decomposed by the exact equivalent of barytic water, by which the sulphuric acid is precipitated, while the free lithia is dissolved, and the solution, if evaporated, leaves hydrate of lithia, LO, HO. 

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