ACTION AND USES: Externally as a caustic, antiseptic and germicide; internally as an astringent. DOSAGE: 0.01 Gm. or 1/6 grain (U.S.P.), diluted or in kaolin pills. The concentrations of solutions for local use vary from 0.01 to 10 per cent., according to the sensitiveness of the surface and the degree of action desired. Distilled water should be used in making the solutions. _*Argenti Nitras Fusus (Arg. Nit. Fus.), Molded Silver Nitrate, U.S.P._ (Fused Silver Nitrate, Lunar Caustic).--AgNO{3} toughened by the addition of a small proportion of silver chloride. White, hard pencils or cones. =Argenti Oxidum (Arg. Oxid.), Silver Oxide, U.S.P.=--Ag{2}O. A heavy, odorless, brownish-black powder with a metallic taste. Only slightly soluble in water; insoluble in alcohol. ACTION AND USES: Astringent in gastric ulcer. Probably inefficient. DOSAGE: 0.06 Gm. or 1 grain (U.S.P.). =Arnica (Arnic.), Arnica, U.S.P.= (Arnica Flowers). ACTION AND USES: Feeble rubefacient. Still used externally to some extent in the form of a tincture mixed with water as an evaporating lotion. The chief active ingredient of the tincture is probably its alcohol. _Fluidextractum Arnicae (Fldext. Arnic.), Fluidextract of Arnica, N.F._--Arnica (100%). Absolute alcohol content about 40 per cent. _Tinctura Arnicae (Tr. Arnic.), Tincture of Arnica, U.S.P._--Arnica (20%) in diluted alcohol. Absolute alcohol content about 46 per cent. =Arseni Iodidum (Arsen. Iod.), Arsenous Iodide, U.S.P.= (Arsenic Iodide).--AsI{3}. An orange-red, odorless powder. Soluble in water (1:12) with partial decomposition; soluble in alcohol. ACTION AND USES: Similar to those of arsenic trioxide, over which it has no advantage. DOSAGE: 0.005 Gm. or 1/12 grain (U.S.P.). _*Liquor Arseni et Hydrargyri Iodidi (Liq. Arsen. et Hydrarg. Iod.), Solution of Arsenous and Mercuric Iodide, U.S.P._ (Donovan's Solution).--Arsenous iodide and red mercuric iodide (each 1%) in water. DOSAGE: 0.1 Cc. or 1-1/2 minims (U.S.P.). =*Arseni Trioxidum (Arsen. Triox.), Arsenic Trioxide, U.S.P.= (Arsenous Acid, Arsenous Oxide, White Arsenic).--As{2}O{3}. Amorphous, glassy masses or white, crystalline masses or powder. Slowly soluble in water (about 1:100), slightly soluble in alcohol and ether and freely soluble in glycerine. Readily dissolved by hydrochloric acid or by alkaline solutions. ACTION AND USES: Believed to modify nutrition. Used as tonic in anemias, nervous diseases, etc., in skin diseases and in some forms of malaria. Externally, a mild escharotic, but the danger of poisoning prevents its general use. Likely to produce nephritis. A very common poison. DOSAGE: 0.002 Gm. or 1/30 grain (U.S.P.), in pills or solutions.