This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Aurum vel Sol Pharm. Paris. Gold: a yellow metal, extremely ductile; above nineteen times heavier than water; fusible in a low white heat; fixt and indestructible in the fire; not soluble by any of the simple acids, in the com -mon ways of making solutions; easily dissolving in a mixture of the nitrous and marine acids, called aqua regis, into a yellow liquor which stains the skin purple.
Essential oils, shaken with this solution, imbibe the gold from the acid, and carrying it up to the surface, keep it there for a time dissolved; but gradually throw it off again, on standing for some hours, in form of bright yellow films, to the sides of the glass. The ether or spiritus vim aethereus takes up the gold more readily and completely, and keeps it permanently dissolved, Rectified spirit of wine mingles uniformly with the acid solution; but on standing for some days, the gold separates from the mixture, and rises in films to the surface. A piece of tin, placed in the solution largely diluted with water, changes it red or purple, and throws down a precipitate of the same colour. By the appearances resulting from these additions, very minute portions of gold, dissolved in acid liquors, may with certainty be discovered.
This metal is found chiefly native: in small granules or filaments; intermingled among earths, or bedded in stones; in the mines of the Spanifh West-Indies, among the sands of some of the African coasts and of some European rivers, and blended with the ores of some other metals. According to the nature of these admixtures, and their degree of union with the gold, the extraction of the metal is differently effected; by ablution with water; by amalgamation with mercury; by bringing the whole matter, that contains the gold, into fusion by fire, with the addition of proper fluxes.
Gold was introduced into medicine by the Arabians, and held to be one of the greatest cordials and comforters of the nerves. As it apparently can have no medicinal effect in its gross state, not being dissoluble by any fluid that can exist in the bodies of animals; the chemists have attempted to subtilize and resolve it, and to extract what they called an anima or sulphur from it. But as no means have been discovered of separating the component parts of this metal, their tinctures and aurum potabiles either contained none of the gold, or were no other than diluted solutions of its whole sub-stance. That the aurum potabile of the faculty of Paris, reckoned one of the belt of the preparations of this kind, (made by shaking some oil of rosemary with a solution of gold in aqua regis, and afterwards digesting the oil for a month in rectified spirit of wine) retains none of the gold, is obvious from the characters of this metal above laid down.
Tinct. auri feu aurum potabile Ph. Paris.
Solutions of gold in aqua regis are corrosive: so far diluted, as that they can be taken with safety, they are, according to Hoffman, purgative: the dry matter left upon infpiffating them, is a strong caustic. The purple precipitate, made by adding pure tin to the solution, is said to be diaphoretic: a precipitate made by alkalies is strongly purgative and emetic. This last precipitate washed from the adhering saline matter by repeated affusions of water, purges more moderately, though rarely without gripes, and sometimes operates by sweat: it has been given, from half a grain to five or six grains, in fevers, and in convulsive and other disorders arising from, or supported by, crudities in the first passages: but as its operation is extremely variable, as it has often produced dangerous symp-toms(a), and as its best effects are no other than what may be obtained from medicines of known safety, it is now, in this country, entirely in difuse; being regarded only as a matter of curiosity, on account of its property of exploding violently when heated or strongly rubbed*(b).
Some have amalgamated gold with pure quicksilver, and set the compound to calcine, as directed in page 151, for the calcination of mercury by itself, till it was converted into a red powder: others have melted the gold with twice its weight or more of martial regulus of antimony, and exposed the powdered mixture, in a glass vessel, to a moderate heat, till the powder became purple. That these kinds of preparations have very considerable medicinal virtues, is not to be questioned; but that those virtues have any dependence upon the gold, is scarcely to be presumed: all that can be rationally expected from this ingredient, is, to ob-tund the activity of the mercurial calx, and of the not fully calcined antimonial metal. When gold is thus divided by the admixture of other metallic bodies, and in some degree calcined along with them, it proves dissoluble in one of the mineral acids which would not touch it before, to wit, spirit of salt; but the acids of the vegetable and the animal kingdom, it still refills as permanently as fine gold in the mass.
(a) Ludovici, Pharm. moderno seculo applicanda, diss. i. oper. p. 102. Stahl, Digram. de proexeucriseos dignitate, sect. viii. Hoffman, Philosopyhia corp. human. morbos. par. ii. cap, viii. § 13.
* (b) Aurum fulminans is still in use in Germany. A late writer (M. A. Plenciz.) recommends it in every case where a sure and safe laxative is wanted; alledging that it does not act with the violence many practitioners have asserted.
Aurum ful-minans Ph. Paris.