part ii. Materia Meijica. — Guaiacwn officinale. 315

Qualities. — It has scarcely any odour; but the taste is verybitter and nauseous. Boiling water extracts its sensible quali-ties more perfectly than alcohol. The colour of the infusionapproaches to that of Madeira wine; it slightly reddens litmuspaper, and strikes an olive colour with a solution of sulphate ofiron without occasioning a precipitate. When sulphuric acidis added to the unstrained infusion, it emits the odour of tama-rinds ; and when the infusion is filtered and slowly evaporated,spicular crystals are formed, which appear to be tartaric acid.

Medical properties and uses. — Gratiola is cathartic, diuretic,and emetic, producing in very large doses all the effects of anirritative poison. It has been much recommended by the Ger-man physicians in dropsy; and has also been used in jaundice,and worm cases. Hufeland found it extremely efficacious invisceral obstructions, and scrophulous affections *: and we areeven told that in the Vienna hospital it has cured the most con-firmed cases of lues venerea ! *

It is given either in the form of powder, or of infusion com-bined with aromatics. The dose of the powder is grs. xv. to3 ss; that of the irifusion, made with aij. of the dried herband Oss of warm water, from f ?iv. to fjj. three times a day.

GUAIACUM. 3 Spec. Plant mild. ii. 538.CI. 10. Ord. I. Decandria Monogynia. Nat. ord. Grui'nafes, Linn.

Rotaceae, Juss.G. 819. Calyx five-parted, unequal. Petals five, inserted into the

calyx. Capsule angular, three or five-celled.Species 2. G. officinale. Officinal Guaiacum. Med. Bot. Id edit. 557.

t.200.Officinal. Guaiaci resina et lignum,- Lond. Guaiaci offici-nalis Lignum-resina, Edin. Guaiacum; lignum, gummi-resina, Dub. The wood and resin of Guaiacum.

Syn. Guyac {F-), Guajakgummi (G.), Guajaco (/.), Guayaco (S.).

This tree is a native of Jamaica, Hisjmniola, and the warmerparts of America. 4 It rises forty feet in height, and is four orfive in circumference, with many divided knotted branches.The bark of the trunk is of a dark grey colour, variegated withgreenish or purplish specks, but that of the branches is ash-coloured, with fissures. The leaves are abruptly pinnate, con-sisting of two or three pair of smooth, shining, veined, obovate,dark green leaflets, almost sessile. The flowers are peduncledin kind of umbels, which spring from the divisions of thesmaller branches. The calyx consists of five, concave, oblong,blunt, spreading, unequal, deciduous leaves; the petals arefive, of a rich blue colour, elliptical, concave and spreading.

1 Hufeland vber die Natur, &c der Scrofula.

' : Kostrewski, Dissert, dc Gratiola, p. 64.

3 The Spanish name Giuu/aco, is derived from the Caribbee. Humboldt.

• The tree was cultivated in this country by the Duchess of Beaufort, 1699.