LITHIA - OXIDE OF LITHIUM, L2O, = 30.

Characters And Tests

Occurs in white granules, forms salts with acids, and has a high power of saturation, 15 parts neutralizing as much acid as 41 of soda or 47 of potash. For uric acid it has a special affinity, and will abstract it from portions of gouty bone and cartilage placed in warm solutions of the drug (Garrod).

The most characteristic tests for lithium are the carmine red color it imparts to flame, and the two lines which it develops on the spectrum, viz., one bright red line at point 82 of the micrometer, and one pale yellow line at 94. Of substances which resemble it, potassium has its red line at 68, sodium its yellow line at 100, and strontium has an additional line of blue.

LITHIAE CARBONAS - CARBONATE OF LITHIA, L2CO3,=74.

Preparation

From sulphate or chloride of lithium by adding carbonate of ammonium.

Characters

Occurs in white powder, or crystalline grains, having an alkaline taste and reaction: is insoluble in alcohol, but slightly soluble in water (1 part in 100, or about 4 gr. to the ounce): carbonic acid increases the solubility to 5 parts per 100.

LITHIAE CITRAS - CITRATE OF LITHIA, L3C6H1O7,=210.

Preparation

By dissolving the carbonate in citric acid, evaporating the liquid, and drying and pulverizing the residue.

Characters

A white amorphous powder, anhydrous, deliquescing on exposure, entirely soluble in two and a half times its weight of water: it is somewhat unstable in composition, and requires to be carefully kept from the air.

Some other compounds of lithia are likely to be used, but are not officinal.

The urate is very soluble, more so than the urates of potash or soda.

The benzoate, which is prepared from the carbonate by adding benzoic acid to the hot solution (Pharmaceutical Journal, July, 1875), occurs in glistening, pearly scales, of soapy feel, acid reaction, and cool, sweetish taste: it is soluble in three and a half parts of cold water, and ten of alcohol - it is thus more soluble than the carbonate, while it is more stable than the citrate, and has the advantage of containing an acid itself valuable in the treatment of urinary deposits.

A ferruginous benzoate of lithia has been prepared by M. Trehyon (Progres Medicale, July 25, 1874) and is recommended both as a non-irritant form of benzoic acid, and as a tonic and preventive of the anaemia produced more or less by all alkalies.

The bromide may be prepared by direct combination, and obtained in transparent crystals which are deliquescent. It contains a large proportion of bromide (92 percent.), while the analogous salt of potassium contains only 66, and of sodium 78 per cent. (S. Weir Mitchell: American Quarterly Journal, October, 1870). The salt is used for photographic purposes.

Absorption And Elimination

Lithia salts are rapidly absorbed: thus, from the experiments of Dr. Bence Jones, it appears that if 3 gr. of the chloride be given to an animal on an empty stomach, it may be detected even in the cartilage of the hip-joint, and the aqueous humor of the eye in a quarter of an hour: 7 gr. having been given to a parturient woman eight hours before delivery, lithia was afterward detected in every part of the umbilical cord, and 20 gr. of the carbonate having been taken three and a half hours before an operation for cataract, ample traces of lithia were detected in the lens when removed: four days afterward, lithia could still be detected in the secretions, and was not wholly eliminated till the end of seven days ("Lectures," p. 16). It is excreted chiefly by the kidneys.

Physiological Action (Internal)