Hydrargyri Oxidum Rubrum (Hydrarg. Oxid. Rub.), Red Mercuric Oxide, U.S.P. (Red Precipitate).—HgO.
Heavy, orange-red scales or powder, odorless and with a somewhat metallic taste. Almost insoluble in water; insoluble in alcohol, readily dissolved by nitric acid.
Action and Uses: Occasionally used externally in the form of an ointment and as a parasiticide. Without advantage over yellow oxide.
Unguentum Hydrargyri Oxidi Rubri (Ung. Hydrarg. Oxid. Rub.), Ointment of Red Mercuric Oxide, N.F.—Red mercuric oxide (10%) in water, hydrous wool fat and petrolatum.
*Hydrargyri Salicylas (Hydrarg. Salicyl.), Mercuric Salicylate, U.S.P. (Mercuric Subsalicylate).—Contains Hg (about 57%).
White or nearly white, odorless, tasteless powder. Nearly insoluble in water or alcohol. Dissolved by solutions of the fixed alkalies or their carbonates.
Action and Uses: Used as antisyphilitic especially by intramuscular injection of oily suspensions; also as local antiseptic.
Dosage: 0.004 Gm. or 1/15 grain (U.S.P.). By intramuscular injection, 0.6 Cc. or 10 minims of a 10 per cent. suspension in liquid petrolatum once in four days.
*Hydrargyrum (Hydrarg.), Mercury, U.S.P. (Quicksilver).—Hg.
Shining, silver-white, odorless, tasteless metal, liquid at ordinary temperatures. Insoluble in the ordinary solvents.