Logwood
Botanical: Haematoxylon Campeachianum (LINN.)
Family: N.O. Leguminosae
---Synonyms---Haematoxylon Lignum. Lignum Campechianum. Lignum Coeruleum. Peachwood. Bois de Campechey de Sang or d'Inde. Bloodwood.
---Part Used---The heart-wood, or duramen, unfermented.
---Habitat---Tropical America, especially the shores of the Gulf of Campeachy. Naturalized in West Indies and elsewhere.
---Description---The name of the genus comes from the Greek and refers to the blood-red colour of the heart-wood. Haematoxylon Campeachianum is a crookedly-branched, small tree, the branches spiny and the bark rough and dark. The leaves have four pairs of small, smooth leaflets, each in the shape of a heart with the points towards the short stem. The flowers, small and yellow, with five petals, grow in axillary racemes.
The tree was introduced into Jamaica and other countries in 1715 and has been grown in England since 1730.
The average yearly import of logwood into the United Kingdom is about 50,000 tons, the four kinds recognized in the market, in order of value, being Campeachy, Honduras, St. Domingo and Jamaica.
The trees are felled in their eleventh year, the red heartwood, in 3-foot logs, being exported.
The principal value of logwood is in dyeing violet, blue, grey and black. For dyeing, the wood is chipped and fermented, thus rendering it unsuitable for medicinal use.
The many disputes and difficulties that arose over the rights of growing and cutting logwood are a matter of history. It is used also as a microscopical stain. The odour is faint and pleasant, the taste astringent and sweetish. It gives a reddish-violet tinge to water made alkaline with a solution of sodium hydroxide.
---Constituents---A volatile oil, an oily or resinous matter, two brown substances, quercitin, tannin, a nitrogenous substance, free acetic acid, salts, and the colouring principle Haematoxylin or Haematin (not the haematin of the blood). The crystals are colourless, requiring oxygen from the air and an alkaline base to produce red, blue, and purple.
Haematein, produced by extraction of two equivalents of hydrogen, is found in dark violet crystalline scales, showing the rich, green colour often to be seen outside chips of logwood for dyeing purposes.
---Medicinal Action and Uses---A mild astringent, especially useful in the weakness ofthe bowels following cholera infantum. It may be used in chronic diarrhoea and dysentery, in haemorrhages from uterus, lungs, or bowels, is agreeable to take, and suitable whether or not there is fever. It imparts a blood-red colour to urine and stools. It is incompatible with chalk or limewater. The patient should be warned of these two characteristics.
In large doses haematoxylin can produce fatal gastro-enteritis in lower animals.
The infusion, internally, combined with a spray or lotion, is said to have cured obstinate cases of foetid polypus in the nose.
---Preparations and Dosages---Decoction, 2 to 4 fluid ounces. Decoction, B.P. 1895, 1/2 to 2 OZ. Solid extract, B.P. 1885, 10 to 30 grains. Solid extract, U.S.P., 2 to 5 grains.
---Other Species---
'BASTARD LOGWOOD' from Acacia Berteriana and other species, contains no haematoxylin. It does not form a violet colour with alkalies, but yields a pure, yellowish-grey dye.
BRAZIL WOOD, a product of Caesalpinia, is distinguished by forming a red colour with alkalis. It is now used only as a dye.
WEST INDIAN LOGWOOD is Ceanothus Chloroxylon.
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