This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
Haematoxylon. - Synonym. - Logwood. The heart-wood of Haematoxylon campechianum Linne (nat. ord. Leguminosae).
Central America; naturalized in the West Indies.
Heavy, hard, externally purplish-black, internally brownish-red, and marked with irregular, concentric circles, splitting irregularly; odor faint, agreeable; taste sweetish, astringent. When chewed, it colors the saliva dark pink. Logwood is generally met with in the form of small chips or coarse powder of a dark brownish-red color, often with a greenish lustre. Resembling Logwood. - Red Saunders, which is more dense and less astringent.
The chief constituents are - (1) Tannic Acid. Haematoxylin, C16H14O6, 12 per cent. Occurring in sweet, colorless crystals, which become dark-red on exposure to light. Solutions of it are used to stain histological specimens. (3) Haemalein, C16H12O6, a product of oxidation of the former, having a green, metallic lustre.
In virtue of its tannic acid, logwood is a powerful astringent, and for this purpose is used to control diarrhoea of all sorts. It may be combined with other astringents, as chalk and with opium to check peristalsis. It does not easily produce constipation. It colors the urine and faeces dark red. One disadvan tage of it is that it stains linen, if it comes in contact with it.