GUAIACUM, LIGNUM VITÆ, or Pockwood; a genus of the monogynia order, belonging to the decandria class of plants.
Species. 1. The officinale, or common lignum vitæ used in medicine, is a native of the West India islands. There it becomes a large tree, having a hard, brittle, brownish bark, not very thick. The wood is firm, solid, ponderous, very resinous, 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 sanctum, 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 bastard lignum vitæ. 3. The Alpum 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-store, 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. Ulric Hutten says this wood was introduced into Europe in 1517; but Brassavolus says, not until 1525. It is brought from the West Indies, in large pieces, each weighing from four to five hundred weight: it is hard, compact, and so 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 has little or no smell, except when heated, 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 of guaiac, there are two kinds, one smooth, the other unequal on the surface; they are both of them weaker than the wood.
The gum, or rather resin, exudes from the tree; and is of a brown colour, partly reddish, and often greenish, brittle, having a glossy surface when broke, of a pungent taste, affecting the tongue and palate in the same manner as is said of the wood. The chief of what is brought to us is in irregular masses, of a dusky green colour. There is a sort in drops, which is the best, but is very rarely met with.
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 rasps or chips are kept a while. In choosing the gum, prefer those pieces which have slips of the bark adhering to them, and that easily separate therefrom by a quick blow.
Neumann assures us, that a composition of colophony and balsam of sulphur is imposed on the unwary for true gum guaiacum; but the cheat is easily detected by exposing it to a due degree of heat, by which the odour of the false is perceived to be quite different from that of the true.
The guaiac wood was first introduced into Europe as a remedy for the venereal disease. It is a good assistant to mercury, as it warms and stimulates, and so promotes perspiration and urine; it also proves gently purgative in a somewhat increased dose: and these seem to be its primary virtues. When the excretory glands are obstructed, the vessels lax and flaccid, the habite replete with serous humours, in many cutaneous and catarrhous disorders, some female weaknesses, in gouty complaints, and rheumatic disorders, it produces good effects. The hectic fever which sometimes follows a salivation, gives way to a decoction of the woods.
A long use of this medicine hath been observed to produce a yellowness in the skin. In thin emaciated habits and an acrimonious state of the fluids, it often does harm. It is also improper in hot bious habits, and where the fibres are very tense.
Three ounces of the wood, or four ounces of the bark, may be boiled in 4 lb. of water to 2 lb. and if a little liquorice is added at the latter end of the boiling, or when the decoction is taken from the fire, it will abate the disagreeable pungency of this medicine, which affects the throat very much in swallowing it. Of this decoction, at least half a pint should be taken in a day. Of the gum, or extract, the dose may be from gr. v. to ii. which last purges pretty much. These should be dissolved by the mediation of egg, or the mucilage of gum arabic; for otherwise they do not easily mix the juices in the stomach.
A pound of guaiacum wood, distilled over an open fire, gave 3 iiii of acid, which is called spirit, and iiii of empyreumatic oil.—An hard extract of guaiacum is accounted an excellent errhine.
The wood of this tree is so hard, that it breaks 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.