Haematoxyli Lignum. Br.
"Logwood is the heart-wood of Haematoxylon campecheanum, Linn." Br. "The heart-wood of Haematoxylon campechianum Linne (Fam. Leguminosae) that has not undergone fermentation." N. F.
Haematoxylon, N. F.; Lignum Campechianum, Lignum Coeruleum; Bois de Campeche ou Bois d'Inde, Fr. Cod.; Bois de Sang, Fr.; Blauholz, Campecheholz, Blutholz, Kampeschenholz, G.
Haematoxylon campechianum is a tree of middle size, usually not more than twenty-four feet high, though, under favorable circumstances, it sometimes rises forty or fifty feet. The trunk is often very crooked, and is covered with a dark rough bark. The branches are beset with sharp spines. The sap-wood is yellowish, but the interior layers are of a deep-red color. The leaves are alternate, abruptly pinnate, and composed of three or four pairs of sessile, nearly obcordate, obliquely nerved leaflets. The flowers, which are in axillary spikes or racemes near the ends of the branches, have a brownish-purple calyx and lemon-yellow petals. They exhale an agreeable odor, said to resemble that of the jonquil.
The tree is a native of Campeche, the shores of Honduras Bay, and other parts of tropical America, and has become naturalized in Jamaica. It is cultivated in tropical America and Asia. The wood, which is the part used in medicine, is a valuable article of commerce, and largely employed in dyeing. It comes to us in logs deprived of the sap-wood and having a blackish-brown color externally. It has been estimated that about 400,000,000 pounds of log-wood are annually consumed. In 1912 Haiti exported about 83,000,000 pounds of logwood to the United States. (See A. J. P., 1912, p. 86.) According to Louis Siebold, the ground or chipped logwood of commerce is unfit for use as a medicinal agent, because it has been prepared as a dyestuff by being exposed in large moist heaps until its hematoxylin has been converted by oxidation into hematein. As a coloring agent, for commercial purposes, this fermented logwood, according to Siebold, is much superior to the natural wood. An inferior variety of logwood which contains little or no hematoxylin, but a pure yellowish-gray dye is that known as bastard logwood. According to the researches of E. S. Earl this bastard logwood is produced by a variety of the species, which, when growing, cannot be distinguished from the ordinary form. (B. D. A. J., i, 31.)
Properties.—Logwood is hard, compact, heavy, of a deep-red color, becoming purplish-black by exposure, internally brown-red, and marked with irregular, concentric circles, splitting irregularly, of a slight peculiar odor, and a sweet, somewhat astringent taste. Logwood is officially described as "Hard, heavy, dull orange to purplish-red externally and reddish-brown internally. In transverse section, alternating yellowish-brown and dark brown wavy tangential lines. In the form of chips or coarse powder, it is free from signs of fermentation, and from green metallic lustre. Slight, agreeable odor; taste sweetish, astringent. Readily imparts a reddish-violet color to water made slightly alkaline with solution of sodium hydroxide" Br.
The N. F. IV description is as follows: "Usually in small chips, reddish-brown, the freshly cut surface dark yellowish-red; a transverse section of the wood shows medullary rays which are up to four cells wide. Odor faint, agreeable; taste sweetish, astringent. Hematoxylon imparts a yellowish color to water containing a little acid, the color being changed to purple or violet-red by alkalies. The powder is reddish-brown and, when examined under the microscope, exhibits medullary ray cells in one to seven rows; wood fibers, long, with thickened walls; wood parenchyma with occasional crystals of calcium oxalate; tracheas from 0.09 to 0.17 mm. in width; walls of the cells colored brownish-red, the inner cells containing resin masses. Hematoxylon yields not more than 3.5 per cent. of ash." N. F.
Its solution affords precipitates with sulphuric, nitric, hydrochloric, and acetic acids, alum, copper sulphate, lead acetate, and ferrous sulphate, striking a bluish-black color with the last mentioned salt. Precipitates are also produced with it by lime water and gelatin. Chevreui found in logwood a volatile oil, an oleaginous or resinous matter, a brown substance the solution of which is precipitated by gelatin (tannin), another brown substance soluble in alcohol but insoluble in water or ether, a nitrogenous substance resembling gluten, free acetic acid, various salts, and a peculiar principle called haematoxylin or haematin (which must not be confused with the haematin of the blood), on which the coloring properties of the wood depend. This is obtained by digesting the aqueous extract in alcohol, evaporating the tincture until it thickens, then adding a little water, and submitting the liquid to a new but gentle evaporation. Upon allowing it to rest, hematoxylin is deposited in crystals, which may be purified by washing with alcohol and drying. Thus procured, the crystals are shining, of a yellowish-rose color, bitterish, acrid, and slightly astringent to the taste, readily soluble in boiling water, forming an orange-red solution which becomes yellow on cooling, and soluble also in alcohol and ether. According to Erdmann, who obtained hematoxylin by the process of Chevreui, substituting ether for alcohol, its crystals, when quite pure, are colorless, without a tinge of redness; its taste is sweet, like that of licorice, without bitterness or astringency; and it is not of itself a coloring substance, but affords beautiful red, blue, and purple colors, by the joint action of an alkaline base and the oxygen of the air. He obtained from logwood 9 to 12 per cent. of crystallized hematoxylin, to which he gave the formula C16H14O6. It crystallizes with 1 or with 3 molecules of water, and is readily soluble in hot water or alcohol, but sparingly in cold water or in ether. (J. Pr. Chem., xxxvi, p. 205.) By the combined action of ammonia and oxygen dark violet crystalline scales of hematein, C16H12O6 + 3H2O, are produced. They show a fine green hue, which is also very commonly observable on the surface of the logwood chips of commerce. Hematein may again be transformed into hematoxylin by means of nascent hydrogen or of sulphurous acid. Commercial extract of logwood extracted from the wood by boiling water contains both hematoxylin and hematein. Hematoxylin, in alcoholic solution, is used as an indicator in the U. S. P. IX. (See Hematoxylin Test-solution, Part III.)
Uses.—Logwood is a mild astringent, devoid of irritating properties, and well adapted to the treatment of that relaxed condition of bowels which is apt to succeed cholera infantum. It is also occasionally used with advantage in ordinary chronic diarrhea and chronic dysentery. Hematoxylin was found by Combemale (B. M. N., xxxiii, 1894) to be very feebly antiseptic, but capable in large doses of producing fatal gastro-enteritis in the lower animals. It is used not only as a dye-stuff but also as a microscopical stain.
Dose, from ten to thirty grains (0.65-1.9 Gm.).
Off. Prep.—Decoctum Haematoxyli, Br.
The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.