This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
This is the inner or heart-wood of Haematoxylon Campechi-anum, a tree of medium size, growing in Campeachy and on the shores of the Bay of Honduras, in the Peninsula of Yucatan, and in Jamaica and other West India islands, into which it is said to have been introduced from the Continent.
Sensible Properties. It comes in billets of various magnitude, hard, compact, and heavy, of a red or yellowish-red colour, becoming darker and almost black by exposure, of a peculiar not disagreeable odour, and a sweet somewhat astringent taste. As kept in the shops for use, it is in small chips, or in the form of a coarse powder produced by rasping. It yields its virtues, with a deep purplish red colour, to water and alcohol.
Its chief constituents are a variety of tannic acid in small proportion, in which its astringency resides, and a peculiar colouring principle called haematoxylin, to which it owes its colouring properties and sweetness.
Chemical Reactions. The decoction of logwood produces precipitates with lime-water, acetate of lead, and alum, a deep-violet blue with the salts of sesquioxide of iron, and reddish curdy flakes with a solution of gelatin.
The effects of logwood on the system are those of a pure mild astringent, without bitterness, and without irritant properties. The colouring principle appears to be absorbed, as the urine is reddened by the internal use of the medicine.
This astringent is applicable to mild cases of diarrhoea and chronic dysentery, in which simple astringency is required, and more irritating substances might be injurious. It is especially suited to the diarrhoea of children, and has been considerably employed in that form of it which succeeds cholera infantum, after the violence of the disease has been subdued. It may be used also for the general purposes of the vegetable astringents, but is too feeble for much effect, unless in cases of the kind above referred to.
The only two forms in which it is used are those of the Decoction (Decoctum Haematoxyli, U. S.) and Extract (Extractum Haematoxyll, U. S.), both of which are officinal. In the former U. S. Pharmacopoeia, the process of which I prefer, the decoction was pre-pared by boiling an ounce of the rasped wood with two pints of water to a pint; and two drachms of bruised cinnamon might sometimes be usefully added at the end of the boiling. The dose is two or three fluid-ounces for au adult, two or three fluidrachms for a child of two years, to be repeated three or four times a day, or more frequently if required. The dose of the extract is from ten to thirty grains. It may be given in the form of pill or solution; bat, if pills are preferred, they should be taken freshly prepared; as they are said to become so hard, by long keeping, as sometimes to pass through the bowels unchanged.