Sources of Lithium. - Native silicates and phosphates of lithium and other metals.

Reaction. - It is recognised by the red colour which it gives to flame. This appears to be more brilliant when the salt is first converted into chloride by addition of hydrochloric acid.

General Impurities of Lithium. - Alkalis, alkaline salts, and metals.

Preparation Of Lithium Salts

Lithium Salt

Is prepared from

By

Carbonate, B. and U.S.P.

Lithium chloride obtained from minerals

Precipitating with carbonate of ammonium.

Citrate, B. and U.S.P.

Lithium carbonate .

Dissolving in citric acid.

Benzoate, U.S.P. .

Ditto .

Neutralising in hot solution with benzoic acid, filtering, and evaporating to dryness, or crystallising.

Salicylate, U.S.P. .

Ditto .

Neutralising hot solution with salicylic acid, filtering, and evaporating.

Bromide, U.S.P. .

Ditto .

Neutralising with sulphuric acid, and decomposing the sulphate thus obtained by bromide of potassium.

Tests. - The alkalis are detected by igniting the lithium salt and converting the carbonates which remain (when the acid has been an organic one, as citric or salicylic) into chloride by the addition of hydrochloric acid. On evaporating the filtered solution to dryness, 1 part of the residue should be completely soluble in 3 parts of alcohol, and should give no precipitate on the addition of an equal volume of stronger ether, U.S.P. (Alkaline salts, if present, would give a precipitate.) A solution in water of another portion of the residue should give no precipitate with a solution of oxalate of ammonium (absence of alkaline earths), and no precipitate or colour with hydrosulphuric acid or ammonium sulphide (absence of metals, U.S.P.).

General Action of Lithium Salts. - The action of lithium upon muscle, nerves, and nerve-centres is very much like that of potassium (vide p. 605), but is more powerful.