"Take of nitric acid, by measure, one part; muriatic acid, by measure, two parts. Mix them together in a vessel kept cool, and preserve the mixture in a cool obscure place."

Syn. Acide hydro-chloro-nitrique: Eau regale (F.).

This mixed acid exhales the odour of chlorine: it is of a golden-yellow colour, and has the property of dissolving gold and platina. On heating the mixture the colour deepens, and both chlorine and nitrous acid vapours are evolved. If the heat be long continued, the chlorine ceases to be given off, the mixture no longer acts as a solvent of gold, and is in fact a mixture of nitrous and hydrochloric acids. It is probable that at first both acids are partially decomposed, water and nitrous acid formed, and chlorine is evolved.

Medical properties and uses. - This mixed acid, when properly diluted, exerts a tonic and stimulant influence on the habit. It is, however, chiefly used in the form of a foot bath in hepatic affections; and in deficient secretion of bile. The best proportions for this bath are f. ij. of the mixed acid for each gallon of water. It produces a tingling sensation on the skin; and, augmenting the flow of the bile, it operates as a mild purgative on the bowels.

When taken internally, in an overdose, this acid acts as a virulent poison; exciting violent inflammation, and corroding the coats of the stomach. Its effects are most successfully counteracted by magnesia, albumen, and milk.