LITH′IUM. Li. The metallic base of LITHIA, first obtained by Sir H. Davy by exposing hydrate of lithium in contact with mercury to galvanic action, and decomposing the resulting amalgam by distillation. It is now obtained by fusing pure chloride of lithium in a small, thick, porcelain crucible, and decomposing it while in a fused state by a current of electricity. It is a white metal, like sodium, very oxidisable, fusing at 356°, and having a sp. gr. of ·59. It is the lightest metal known. It belongs to the ‘alkaline group,’ of which potassium, sodium, cæsium, and rubidium, are the other members.
Lithium forms salts analogous to those of sodium, but usually somewhat less soluble. They can be distinguished from those of potassium and sodium by the phosphate and carbonate, being only sparingly soluble in water,—from those of barium, strontium, and calcium, by forming crystallisable and soluble salts with sulphuric acid and oxalic acid,—and from those of magnesium, by the solution of its carbonate exhibiting an alkaline reaction. Heated on platinum, they tinge the flame of the blowpipe carmine red. The salts of lithium may generally be formed by dissolving the hydrate or carbonate in dilute acids.
Lithium, Benzoate. LiC7H5O2,H2O. (Paris Pharm. Society.) Benzoic acid, 122 grams; lithium carbonate, 37 grams. Suspend the benzoic acid in 10 parts of water, add the lithium carbonate, and heat. Solution takes place with effervescence, and upon evaporation, handsome, much flattened, more or less elongated prismatic crystals are obtained.
Lithium benzoate is very soluble in water. One grain of the salt calcined, and then treated with slight excess of sulphuric acid, and heated to redness should give 0·376 gram of lithium sulphate.
Lithium, Bromide of. LiBr. To 37 grams of carbonate of lithium suspended in 200 grams of distilled water, 80 grams of bromine are added. A current of sulphuretted hydrogen is then passed through the mixture until the whole of the bromide has disappeared. Hydro-bromic acid is thus formed, which decomposes the carbonate of lithium, bromide of lithium being produced and sulphur set free. The mixture is then gently heated to drive off the excess of sulphuretted hydrogen and to agglutinate the sulphur. After filtration the liquor is concentrated, and if it be desired to obtain the bromide in crystals, the
desiccation is finished under a bell jar by means of sulphuric acid.
Lithium, Car′bonate of. Li2CO3. Syn. Carbonate of lithia; Lithiæ carbonas (B. P.). Prep. To an aqueous solution of sulphate of lithium add a strong solution of carbonate of ammonium, collect the precipitate, drain, and press, wash with a little rectified spirit, and dry. By dissolving it in boiling water, and slowly evaporating the solution, crystals may be obtained.
Prop., &c. It resembles carbonate of magnesium in appearance; is soluble in about 100 parts of cold water, and in considerably less of boiling water, and is insoluble in alcohol. The tests for its purity given in the B. P. are—in giving no precipitate with oxalate of calcium or lime water, and leaving, when 10 grains are neutralised with sulphuric acid and ignited, 14·86 grains of dry sulphate. It has been proposed by M. Lipowitz, Dr Garrod, and others, as a solvent for uric acid calculi. According to Biswanger, 1 part of carbonate of lithia in 120 parts of water takes up, at blood-heat, nearly 4 parts of uric acid. Mr Alexander Ure recommends a dilute solution of this substance as an injection in lithic calculus, as it is a better solvent of uric acid than either borax or the alkaline carbonates. “Of all the various menstrua hitherto recommended, none appear to promise more favorably than the carbonate of lithia.” “If by means of injections” (of this solution) “we can reduce a stone at the rate of a grain or more an hour, we shall not merely diminish the bulk of the calculus, but further loosen its cohesion, disintegrate it, so to speak, causing it to crumble down, and be washed away in the stream of urine.” (Mr A. Ure.)—Dose, 2 to 5 gr., twice or thrice a day; as an injection, 1 gr. to water, 1 fl. oz.
Lithium, Citrate of. Li3C6H5O7. Syn. Lithiæ citras (B. P.). A white deliquescent amorphous powder, made by acting on 50 grains of lithium carbonate with 100 of citric acid, and is readily soluble in 21⁄2 parts of water.
Tests, &c. 20 grains burnt at a low red heat until white leave 10·6 grains of carbonate of lithium. Its medical properties are similar to those of the carbonate.—Dose, 5 to 16 grains, largely diluted.