Aui-iii = 197.2.
The element gold (AS. geolu, aiolo, yellow; Gr.
L. aurum, yellowish - i. e., color of the metal), official 1830-1840, usually occurs in the metallic state with other metals, but sometimes as sulphide. It is separated from adhering rock, sand, etc., by washing, its greater specific gravity (19.3) causing it to subside. When pure it is quite soft, so that for general use it is alloyed with harder metals. Jewelers recognize the pure metal as 24 carat (seldom employed), and when mixed with 25 p. c. of copper or silver as 18 carat. It is affected by none of the pure acids, being dissolved only by nitrohydrochloric acid, free chlorine or bromine, and mercury, forming with this latter an amalgam.
Tests for Gold Salts: 1. H2S precipitates brown auric sulphide, Au2S3, soluble in ammonium sulphide. 2. FeSO4 added and set aside soon precipitates metallic gold in dark powder, which by fusion is converted into a metallic button. 3. Stannous chloride precipitates purple (of Cassius).
Auri et Sodii Chloridum. Gold and Sodium Chloride. - (Syn., Aur. et Sod. Chlor.,. Chloruretum Aurico-sodicum; Fr. Chloraurate de Sodium, Chlorure d'Or et de Sodium; Ger. Auro-natrium Chloratum, Natriumgoldchlorid.)
Manufacture: Dissolve gold (13) in a mixture of nitric acid (16) and hydrochloric acid (48), add water (40), + pure dry sodium chloride (20), evaporate to dryness with constant stirring - (1) Au2 + 2HNO3 + 8HC1 = 2HAuCl4, or 2(AuCl3 + HC1) +2NO + 4H2O. (2) HAuCl4 + NaCl = NaAuCl4 or (AuCl3 + NaCl) + HC1. It is a mixture of equal parts of anhydrous gold chloride, AuCl3, and anhydrous sodium chloride, NaCl, representing, when dried, at least 30 p. c. of metallic gold; it is an orange-yellow powder, odorless, saline metallic taste, deliquescent in damp air, soluble in water; alcohol or ether dissolves the gold chloride leaving the sodium chloride. Tests: 1. Aqueous solution (1 in 100) slightly acid, + silver nitrate T. S. - white precipitate, insoluble in nitric acid, but soluble in ammonia water. 2. Fragment in non-luminous flame - intensely yellow. Impurities: Free hydrochloric acid, metallic substances. Should be kept in well-stoppered, amber-colored vials. Dose, gr. 1/20 - 1/4 (.003-.016 Gm.); supposed to be an important agent in the "Keeley cure," associated with hypodermics of atropine, strychnine, etc.
Preparation. - (Unoff.): Liquor Auri et Arseni Bromidi - arsenic trioxide .25 Gm., brom. auric acid .325, bromine .4, dist. water q. s. 100. Dose, eiij-5 (.2-.3 Ml. (Cc.)).
Properties and Uses. - Action similar to that of mercury, used for syphilis, scrofula, sclerosis of the spine, liver, and kidneys, hypochondriasis, asthma, dysmenorrhoea, migraine, epilepsy, chorea, hysteria, consumption, habitual inebriety. Externally - caustic, like AgNO3, for lupoid, cancerous, and other ulcers. In addition to the double chloride, the bromide, iodide, and oxide also are used in doses of gr. 1/20-¼ (.003-016 Gm.), after meals; also the powdered metal may be given in doses gr. 1/6-1 (.01-06 Gm.).