(Au. Eq. = 196.5.)

Aurum. Gold. Appendix B. [Not officinal in U. S. P.] Fine gold; in mass or leaf.

Gold, when pure, is a soft, malleable, yellow metal; sp. gr. 19.5; introduced into the Pharmacopoeia for forming a solution. Gold is not acted on by nitric or any other simple acid, only by nitro-hydrochloric acid or chlorine. The test solution of the ter-chloride of gold is formed by dissolving gold in nitro-hydrochloric acid; evaporating to dryness, and re-dissolving the resulting ter-chloride in distilled water. It is used as a test for Atropine, etc.

Therapeutics. Metallic gold in a state of very minute division (Pulvis Auri), the ter-oxide (Au O3) and ter-chloride (Au Cl3), have been employed in medicine. Gold appears to act in a very similar manner to mercury; its use has been chiefly confined to the treatment of venereal and scrofulous affections; as yet its action has not been well made out. The preparation most employed is a double chloride of gold and sodium (Au Cl3, Na CI + 4 HO), which occurs as an orange-coloured salt in quadrangular prisms. Leaf gold is much used by dentists for stopping teeth.

Dose. Of powdered gold, 1/4 gr. to 1 gr.; of ter-oxide, 1/10 gr. upwards; of ter-chloride or of the double salt, gr. 1/20 upwards. The chloride is very poisonous, acting in a manner similar to corrosive sublimate.