colourless fluid; in time however it acquires a yellowish tinge, and the consistence of oil; but though by age it has been found thick like honey, yet it never became solid like other resinous fluids.

Genuine Balsam of Copaiba has a moderately agreeable smell, and a bitterish biting taste, of considerable duration in the mouth: it dissolves entirely in rectified spirit, especially if the menstruum be previously alkalized; when the solution has a very fragrant smell. Distilled with water it yields nearly half its weight of a limpid essen. tial oil; and in a strong heat, without addition, a blue oil.

This, like most other balsams, is nearly allied to the turpentines. It was formerly thought to be an efficacious remedy in various disorders, as pulmonary consumptions, coughs, scorbutic diseases, dropsies, dysenteries, nephritic complaints, internal ulcers, fluor albus, gleets, &c. but though some proofs of its good effects in certain states of many of these diseases may be adduced †, yet as it irritates and heats the system to a considerable degree, few cases occur in which this medicine can safely be given, especially in large doses. It determines powerfully to the kidneys, and impregnates their secretion with its qualities, and has therefore been supposed peculiarly suited to diseases of the urinary passages, but by stimulating these organs it is apt to produce very mischievous consequences, its use is therefore now principally confined to gleets and fluor albus.

If this medicine can be advantageously administered in pulmonary affections, it must be in the absence of fever, and where the excretion from the lungs is unattended with inflammatory congestion §.

"We sometimes find in shops, under the name of Copaiba, a thick, whitish, almost opake balsam, with a quantity of turbid watery liquor at the bottom. This sort, probably, is either adulterated by the mixture of other substances, or has been extracted, by boiling in water, from the bark or branches of the tree." Lewis, M. M. p. 132.

Sce Fuller, Pharm. extemp. p. 275. F. Hoffman, Obs. Phys. chym. p. 24. Lentin, Beobacht. einig. Krankh. 1774. p. 58. Mutis relates, that a woman in Santa Fé, who had been many years affected with a dropsy, in forty days was cured by taking balsam of copaiba, the dose of which she increased to a spoonful night and morning. Nouvelles de la Republique des lettres et des arts. 1786. n. 33. p. 374.

Hoppe has fully set forth its dangerous effects. See D. Fred. Wilh. Hoppe, apud Valentini Indiam literatam. p. 624.

§ Vide Simmons "On the Treatment of Consumptions," p. 36. sq.-Dr. Cullen says, "Whether a certain effect of balsam of copaiba is to be imputed

it may be most conveniently taken in the form of an emulsion, into which it may be brought by triturating it with almonds, or rather with a thick mucilage of gum-arabic, till they are well incorporated, and then gradually adding a proper quantity of water. The dose of the balsam should rarely exceed twenty or thirty drops.

[Ray, Woodv. Labat. Cullen.

SECTION XVIII.

Guaiacum Tree.

Guaiacum Officinale.-LINN.

THIS tree is usually known by the name of lignum vitæ. It grows to the height of forty feet, and to the circumference of four or five, sending forth several large dividing and subdividing knotted branches: the bark of the trunk is of a dark grey colour, variegated with greenish or purplish specks, but of the branches it is uniformly ash-coloured, striated, and marked with fissures; "the roots are very thick in proportion to the size of the tree, and run a great way into the ground, in a perpendicular direction:" the leaves are pin. nated, consisting of two, three, and sometimes four pair of pinnæ, with very short footstalks, smooth, shining, veined, of an inversely oval shape, and dark green colour: the flowers grow in clusters, or umbels, upon long peduncles, which spring from the divisions of the smaller branches; the calyx is of five leaves; these are concave, ob. long, obtuse, patent, unequal, and deciduous; the petals are five, elliptical, concave, spreading, and of a rich blue colour; the stamina are erect, villous, taper from the base, and are crowned with yellowish hooked antheræ; the germen is oval, angular, and in its capsular state assumes the figure we have separately described; the style is short and tapering; the stigma is simple, and pointed; the seeds are solitary, hard, and of an oblong shape.

Linnæus makes three species of the guaiacum, viz. the officinale, sanctum, and afrum; the specific difference between the two former he fixes wholly on the number of the pinne of the leaves, defining to its laxative quality, I cannot determine, but must observe, that I have learned from an empirical practitioner, that it gives relief in hæmorrhoidal affections; and I have frequently employed it with success, viz. given from twenty to thirty drops twice a day." Mat. Med. vol. ii. p. 190.

the first with two-paired leaflets, and the second with many paired leaflets; but the leaves, according to the plant we have figured, commonly consist of three, and sometimes four pair of pinæ, so that this specific description is by no means distinctly characteristic. In a medical sense, the sanctum has been generally considered sy. nonymously with the officinale, and from the investigation we have given this subject, we believe it founded in botanical truth.

This tree is a native of the West India Islands, and the warmer parts of America, and appears from the MS. of Sir Hans Sloane, in the British Museum, to have been first cultivated in this country by the Duchess of Beaufort in 1699. The wood, gum, bark, fruit, and even the flowers of this tree, have been found to possess medi. cinal qualities. The wood is brought here principally from Ja. maica, in large pieces of four or five cwt. each, and, from its hardness and beauty, is in great demand for various articles of turnery ware. It is extremely compact, and so heavy as to sink in water: the outer part is of a pale yellowish colour, the heart is of a dark blackish brown, with a greater or less admixture of green. It scarcely discovers any smell, unless heated, or while rasping, in which circumstances it yields a light aromatic one; chewed, it impresses a slight acrimony, biting the palate and fauces. Its pungency resides in a resinous matter, which is totally extracted by diges tion in rectified spirit, and partially by boiling water. The quantity of solid extract, obtained by rectified spirit, amounts to about onefourth of the weight of the wood; with water, scarcely one-sixth is obtained. 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 jagging. 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 ga thered 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. It contains more resin than the watery extract made from the wood; and more gummy matter than the spirituous extract.— The guaiacum 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. The bark contains less re

sinous matter than the wood, and is consequently a less powerful medicine, though in a recent state it is strongly cathartic. The fruit, (says a late author)" is purgative; and, for medicinal use, far excels the bark. A decoction of it has been known to cure the venereal disease, and even the yaws in its advanced stage, without the use of mercury." The flowers, or blossoms, are laxative, and in Jamaica are commonly given to children in the form of syrup, which in appearance much resembles that of violets. It is only the wood and resin of Guaiacum which are now in general medical use in Europe; and as the efficacy of the former is supposed to be derived merely from the quantity of resinous matter which it contains, they may be considered indiscriminately as the same medicine. Guaiacum was first introduced in the Materia Medica soon after the discovery of America, and previous to the proper use of mercury in the lues venerea, it was the principal remedy employed for the cure of that disease, and its great success brought it into such repute, that it is said to have been sold for seven gold crowns a pound; but notwithstanding the very numerous testimonies in its favour, it often failed in curing the patient, and was at length entirely superseded by mercury; and though it be still occasionally employed in syphilis, yet it is rather with a view to correct other vitia in the habit, than for its effects as an antivenereal.

The general virtues of guaiacum are stated by Bergius to be detergent, sudorific, diuretic, and stomachic, and its use to be in syphilis, rheumatism, tooth-ach, and cntaneous affections; and to these we may add chronic rheumatism, scrophula, and some scirrhous diseases. To Dr. Cullen guaiacum seems analogous to the nature of the balsams and turpentines, he therefore supposes it like these to be very diffusible in the system, and thereby to have a considerable power in stimulating the extreme vessels every where; and in this way he accounts for its power in chronic rheumatism, and from its passing off by the pores of the skin, he considers it, like Bergius, a probable remedy in some cutaneous disorders.

In the Philosophical Transactions for 1806, we have a very complete analysis of this substance: by distillation 100 parts yielded

Hence it is inferred that guaiacum agrees in many respects with the resins, but it differs from them, 1. in the quantity of char. coal it leaves when distilled in close vessels; 2. in the action that nitric acid has upon it; and, 3. in the changes of colour that it undergoes when its solutions are treated with nitric and oxymuriated acids. Its properties may be thus enumerated: it is a solid sub. stance resembling a resin; its colour varies, but is generally green. ish; it is readily dissolved in alcohol; alkaline solutions dissolve it with ease; most of the acids act upon it with considerable energy; if digested in water, a portion is dissolved, the water acquiring a greenish-brown colour; the liquid being evaporated, leaves a brown substance which possesses the properties of an extract, being soluble in hot water and alcohol, but scarcely at all in sulphuric ether, and forming precipitates with the muriates of alumina, tin, and silver. [Linn. Woodv. Lewis. Pantologia. Phil. Trans.

SECTION XIX.

Scammony. Jalap.

Convolvulus Scammonia. Convolvulus Jalapa.-WOODY,

THE genus Convolvulus or Bind-wind is very extensive and embraces not less than a hundred and twenty species distributed over the different quarters of the globe. Of these several are medi. cinal: but the chief are the two enumerated in the title to this section.

1. C. Scammonia. Scammony Bind-weed. This plant grows plentifully about Maraash, Antioch, Edlib, and towards Tripoli in Syria: it was first cultivated in England by Mr. Gerard, in 1597. The root is from three to four feet long, and from nine to twelve inches in circumference, covered with bark of a light grey colour;