238. Haematoxylon, N. F.—Haematoxylon. Logwood.
The heart-wood of Haematox'ylon campechia'num Linné. Usually found in commerce in the form of deep, brownish-red chips.—When the surface has a greenish metallic luster, the wood has undergone fermentation and should be rejected. Odor slight; taste sweetish, astringent.
CONSTITUENTS.—Haematoxylin, C16H14O6, sweet, colorless crystals, giving to the wood its characteristic colors by the combined action of the oxygen of the air and the alkaline bases existing in the wood; it is readily soluble in hot water and alcohol, sparingly in cold water; by the action of ammonia and oxygen in the air dark purple scales of haematein, C16H12O6, are formed, often observable as the fine greenish hue upon logwood chips. This principle gives a blue color with alkalies. Haematoxylon also contains tannin, fat, resin, and a trace of volatile oil. With an alkali haematoxylon gives a purple color, brazil-wood a red color, and red saunders is not affected.
Preparation of Haematoxylin.—To ethereal extract add water and allow to crystallize; add a little H2SO3 or sulphite to prevent oxidation. Yellowish prisms of sweetish taste, violet-blue, with alkalies. Soluble in alcohol and water. Sunlight causes a red color.
ACTION AND USES.—A mild astringent. Dose: 30 to 60 gr. (2 to 4 Gm.), in decoction or extract. A solution of haematoxylon as a staining fluid in microscopy is one of the most useful, as it stains both lignified and cellulose tissue, but not suberin or cutin. It is also one of the very best nuclear stains.
PREPARATION: Ext. Haematoxyli, N.F. Dose, 1 Gm. (15 gr.).