164

PROOFS OF THE PROPERTIES OF GOLD.

SECT. II.

EXPERIMENTAL PROOFS

OF

THE PROPERTIES OF GOLD.

Experiment I.

Gold is not acted on by any acid, the oxigenated muriatic andnitro-muriatic acid excepted.

Introduce some gold-leaf into any acid, no solution will beeffected by it; but if oxigenated muriatic acid, or nitro-muriaticacid, be made use of, a solution will be effected. If the gold-leaf be exposed to the action of the oxigenated muriatic acidin its gazeous state, it takes fire. (See vol. i. p. 33.)

A saturated solution of gold in these acids yields, by evapora-tion, crystals of muriate of gold, of a beautiful yellow colour,not unlike topaxes ; they consist sometimes of truncated octa-hedra, sometimes of tetrahedral prisms. When dissolved inwater they tinge the skin indelibly of a deep purple colour, andproduce the same effect upon almost all animal and vegetablebodies, and even upon marble.

Ration ale. ..The gold robs the acid of part of its oxigen, andbecomes oxidated; the oxigenated muriatic acid, or the nitro-muriatic acid, is converted into simple muriatic acid, in whichstate it is capable of dissolving the oxid of gold, and constituteswith it muriate of gold.