B.P. Gold, Fine. Gold, free from Metallic Impurities. Gold foil is used for stopping teeth and to make the test lolution.

B.P. Solution of Chloride of Gold.

Preparation. - By dissolving gold foil in a mixture of nitric and hydrochloric acids and diluting.

U.S.P. Auri et Sodii Chloridum. Chloride of Gold and Sodium.

A mixture composed of equal parts of dry chloride of gold, AuCl3; 302.4; and chloride of sodium, NaCl; 58.4.

Characters. - An orange-yellow powder, slightly deliquescent in damp air, odourless, having a saline and metallic taste and a slightly acid reaction.

Solubility. - The compound is very soluble in water; at least one half of it should be soluble in cold alcohol.

Reactions. - When exposed to a red heat it is decomposed and metallic gold is separated. A fragment of the compound imparts an intense persistent colour to a non-luminous flame.

Preparation. - By dissolving gold in nitro-hydrochloric acid and evaporating to dryness, chloride of gold is obtained. This is dissolved in water, and mixed with its own weight of pure decrepitated common salt also dissolved in water. The mixed solution is then evaporated to dryness.

Dose. - 1/10 to 1/5 grain (.006-.012 gm.), once or twice a day.

Action. - Salts of gold cause rapid paralysis of the central nervous system in frogs, which appears to affect first the optic lobes and cerebellum, then the cord, and lastly the cerebral lobes (vide p. 183 et seq.). In mammals small doses appear to increase the appetite; larger ones cause symptoms of irritation in the stomach and intestines, viz. loss of appetite, diarrhoea, and emaciation, followed by paralysis of the limbs, a catarrhal condition of the respiratory passages, and death by asphyxia. Large doses injected into the veins cause oedema of the lungs, and rapid death, with convulsions, from asphyxia. In man they are said to increase the secretions, and to produce salivation like mercury, but without stomatitis. They are eliminated in the urine.

Uses. - Salts of gold have been supposed to act like those of mercury and silver. They have been given like mercurial salts in syphilis, scrofula, and cancer; and, like silver s"alts, have been used in myelitis. Gold has been supposed to act specifically on the genital organs, and has been used in chronic uterine inflammation and irritation, and inflammation and neuralgia of the ovaries.