Lignum Vitae, or Rockwood: A genus of the monogynia order, belonging to the decidua class of plants; and in the natural method ranking under the 14th order, Grumales. The calyx is quinquefied and unequal; the petals five, and inferted into the calyx; the capsule is angulated, and trilocular or quinquelocular.
Species. 1. The officinale, or common lignum vitae used in medicine, is a native of the West India Islands and the warmer parts of America. There it becomes a large tree, having a hard, brittle, brownish bark, not very thick. The wood is firm, solid, ponderous, very refrinous, of a blackish yellow colour in the middle, and of a hot aromatic taste. The smaller branches have an ash-coloured bark, and are garnished with leaves divided by pairs of a bright green colour. The flowers are produced in clusters at the end of the branches, and are composed of oval concave petals of a fine blue colour.
2. The fanctum, with many pairs of obtuse lobes, hath many small lobes placed along the mid rib by pairs of a darker green colour than those of the foregoing sort. The flowers are produced in loose bunches towards the end of the branches, and are of a fine blue colour, with petals fringed on the edges. This species is also a native of the West India islands, where it is called bofard lignum vitae.
3. The Afrum, with many blunt-pointed leaves, is a native of the Cape of Good Hope. The plants retain their leaves all the year, but have never yet flowered in this country.
Culture. The first species can only be propagated by seeds, which must be procured from the countries where it naturally grows. They must be sown fresh in pots, and plunged into a good hot-bed, where they will come up in six or eight weeks. While young, they may be kept in a hot-bed of tan-bark under a frame during the summer; but in autumn they must be removed into the bark-stove, where they should constantly remain. The second sort may be propagated the same way; but the third is to be propagated by layers, and will live all the winter in a good greenhouse.
Uses. The wood of the first species is of very considerable use both in medicine and in the mechanical arts. It is so compact and heavy as to sink in water. The outer part is often of a pale yellowish colour; but the heart is blacker, or of a deep brown. Sometimes it is marbled with different colours. It is so hard as to break the tools which are employed in felling it; and is therefore seldom used as firewood, but is of great use to the sugar-planters for making wheels and cogs to the sugar-mill. It is also frequently wrought into bowls, mortars, and other utensils. It is brought over hither in large pieces of four or five hundred weight each; and from its hardness and beauty is in great demand for various articles of turnery ware.
The wood, gum, bark, fruit, and even the flowers of of this tree, have been found to possess medicinal virtues; but it is only the three first, and more particularly the wood and resin, which are now in general use in Europe. The wood has little or no smell, except when heated, or while rasping, and then a slight aromatic one is perceived. When chewed, it impresses a mild acrimony, biting the palate and fauces. Its pungency resides in its resinous matter, which it gives it out in some degree to water by boiling, but spirit extracts it wholly.
Of the bark there are two kinds; one smooth, the other unequal on the surface; they are both of them weaker than the wood; though, while in a recent state, they are strongly cathartic.
The gum, or rather gummy resin, is obtained by wounding the bark in different parts of the body of the tree, or by what has been called jaggging. It exudes copiously from the wounds, though gradually; and when a quantity is found accumulated upon the several wounded trees, hardened by exposure to the sun, it is gathered and packed in small kegs for exportation. This resin is of a friable texture, of a deep greenish colour, and sometimes of a reddish hue; it has a pungent acrid taste but little or no smell, unless heated. The tree also yields a spontaneous exudation from the bark, which is called the native gum, and is brought to us in small irregular pieces, of a bright semipellucid appearance, and differs from the former in being much purer.
In the choice of the wood, that which is the freshest, most ponderous, and of the darkest colour, is the best; the largest pieces are to be preferred too; and the best method is to rasp them as wanted, for the finer parts are apt to exhale when the raspings or chips are kept a while.
In choosing the resin, prefer those pieces which have slips of the bark adhering to them, and that easily separate therefrom by a quick blow. The resin is sometimes sophisticated by the negroes with the gum of the manchinea tree; but this is easily detected by dissolving a little in spirit of wine or rum. The true gum imparts a whitish or milky tinge, but the manchinea gives a greenish cast. Mouch advises a few drops of spirit nitri dulce, to be added to the spiritsolution, and then to be diluted with water, by which the gum is to be precipitated in a blue powder; but the adulteration will appear floating in white stripe, &c.
Guaiacum was first introduced into Europe as a remedy for the venereal disease; and appears to have been used in Spain so early as 1508. The great success attending its administration before the proper use of mercury was known, brought it into such repute, that it is said to have been sold for seven old crowns a pound. It did not, however, continue to maintain its reputation; but was found generally to fail where the disease was deep rooted, and was at length superseded by mercury, to which it now only serves occasionally as an adjuvant in the decoction lignorum, of which guaiacum is the chief ingredient.
The general virtues of guaiacum are those of a warm stimulating medicine; strengthening the stomach and other viscera, and remarkably promoting the urinary and cuticular discharges; hence, in cutaneous defecations, and other disorders proceeding from obstructions of the excretory glands, and where sluggish serous humours abound, they are eminently useful; rheumatic Guaiacum, and other pains have often been relieved by them. They are also laxative. The resin is the most active of these drugs, and the efficacy of the others depends upon the quantity of this part contained in them. The resin is extracted from the wood in part by watery liquors, but much more perfectly by spirituous ones. The watery extract of this wood, kept in the shops, proves not only less in quantity, but considerably weaker than one made with spirit. This last extract is of the same quality with the native resin, and differs from that brought to us only in being purer. The gum or extracts are given from a few grains to a scruple or half a dram, which last dose proves for the most part considerably purgative. The official preparations of guaiacum are, an extract of the wood, a solution of the gum in rectified spirit of wine and a solution in volatile spirit, and an empyreumatic oil distilled from the wood. The resin dissolved in rum, or combined with water, by means of mucilage or the yolk of egg, or in form of the volatile tincture or elixir, is much employed in gout and chronic rheumatism. The tincture or elixir has been given to the extent of half an ounce twice a day, and is sometimes usefully combined with laudanum.