a thin ferous humour, occasionally oozing out of the glands about the mouth and throat.

RHIZOMA RHUBARBI; a genus of the monogyne order, belonging to the cannandia class of plants. There are five species, viz. 1. The rhaponticum, or common rhubarb, hath a large, thick, fleshy, branching, deeply-striking root, yellowish within; crowned by very large, roundish, heart-shaped smooth leaves, on thick, slightly-furrowed foot-stalks: and an upright strong stem, two or three feet high, adorned with leaves singly, and terminated by thick close spikes of white flowers. It grows in Thrace and Scythia, but has been long in the English garden. Its root affords a gentle purge. It is however of inferior quality to some of the following sorts; but the plant being astringent, its young stalks in spring, being cut and peeled, are used for tarts. 2. The palmatum, palmated-leaved true, Chinese rhubarb; hath a thick fleshy root, yellow within; crowned with a very large palmated leaves, being deeply divided into acuminate segments, expanded like an open hand; upright stems, five or six feet high or more, terminated by large spikes of flowers. This is now proved to be the true foreign rhubarb, the purgative quality of which is well known. 3. The compactum, or Tartarian rhubarb, hath a large, fleshy, branched root, yellow within; crowned by very large heart-shaped somewhat lobated, sharply indented, smooth leaves; and an upright large stem, five or six feet high, garnished with leaves singly, and branching above; having all the branches terminated by nodding panicles of white flowers. This has been supposed to be the true rhubarb; which, however, though of su- RHEUM

Perior quality to some sorts, is accounted inferior to the rheum palmatum. 4. The undulatum, undulated or waved-leaved Chinese rhubarb, hath a thick, branchy, deep-striking root, yellow within; crowned with large oblong, undulate, somewhat hairy leaves, having equal foot-stalks, and an upright firm stem, four feet high; garnished with leaves singly, and terminated by long loose spikes of white flowers. 5. The Arabian ribs, or currant rhubarb of Mount Lebanon, hath a thick fleshy root, very broad leaves, full of granulated protuberances, and with equal foot-stalks; and upright firm stems, three or four feet high, terminated by spikes of flowers, succeeded by berry-like seeds, being surrounded by a purple pulp. All these plants are perennial in root, and the leaves and stalks are annual. The roots being thick, fleshy, generally divided, strike deep into the ground; of a brownish colour without, and yellow within: the leaves rise in the spring, generally come up in a large head folded together, gradually expanding themselves, having thick foot-stalks; and grow from one to two feet high, or more, in length and breadth, spreading all round; amidst them rise the flower-stems, which are garnished at each joint by one leaf, and are of strong and expeditious growth, attaining their full height in June, when they flower; and are succeeded by large triangular seeds, ripening in August. Some plants of each sort merit culture in gardens for variety; they will effect a singularity with their luxuriant foliage, spikes, and flowers. And as medical plants, they demand culture both for private and public use.

They are propagated by seeds sowed in autumn soon after they are ripe, or early in the spring, in any open bed of light deep earth; remarking, those intended for medical use should generally be sowed where they are to remain, that the roots, being not disturbed by removal, may grow large. Scatter the seeds thinly, either by broad-cast all over the surface, and raked well in; or in shallow drills a foot and half distance, covering them near an inch deep. The plants will rise in the spring, but not flower till the second or third year; when they, however, are come up two or three inches high, thin them to eight or ten inches, and clear out all weeds; though thus designed always to stand should afterwards be hoed out to a foot and a half or two feet distance: observing, if any are required for the pleasure ground, &c. for variety, they should be transplanted where they are to remain in autumn, when their leaves decay, or early in spring before they shoot: the others remaining where sowed, must have the ground kept clean between them; and in autumn when the leaves and stalks decay, cut them down, and slightly dig the ground between the rows of plants, repeating the same work every year. The roots remaining, they increase in size annually; and in the second or third year many of them will shoot up stalks, flower, and perfect seeds; and in three or four years the roots will be arrived to a large size; though older roots are generally preferable for medical use.

Two sorts of rhubarb are met with in the shops. The first is imported from Turkey and Russia, in roundish pieces freed from the bark, with a hole thro' the middle of each: they are externally of a yellowish colour, and on cutting appear variegated with lively reddish streaks. The other, which is less esteemed, comes immediately from the East-Indies, in length pieces, harder, heavier, and more compact than the foregoing. The first sort, unless kept very dry, is apt to grow mouldy and worm-eaten; the second is less subject to these inconveniences. Some of the more industrious artificers fail to fill up the worm-holes with certain mixtures, and to colour the outside of the damaged pieces with powder of the finer sorts of rhubarb, and sometimes with cheaper materials: this is often so nicely done, as effectually to impose upon the buyer, unless he very carefully examines each piece. The marks of good rhubarb are, that it be firm and solid, but not flinty; that it be easily pulverizable, and appear, when powdered, of a fine bright yellow colour; that, upon being chewed, it impart to the spittle a saffron tinge, without proving slimy or mucilaginous in the mouth. Its taste is tubercid, bitterish, and somewhat astringent; the smell lightly aromatic.

Rhubarb is a mild cathartic, which operates without violence or irritation, and may be given with safety even to pregnant women and children. Besides its purgative quality, it is celebrated for an astringent one, by which it strengthens the tone of the stomach and intestines, and proves useful in diarrhoeas and disorders proceeding from a laxity of the fibres. Rhubarb in infusion operates more powerfully as a cathartic than any of the preparations of it. Watery tinctures purge more than the spirituous ones; whilst the latter contain in greater perfection the aromatics, astringent, and corroborating virtues of the rhubarb. The dose, when intended as a purgative, is from a scruple to a dram or more.

The Turkey rhubarb is, among us, universally preferred to the East-India sort, though this last is for some purposes at least equal to the other; it is manifestly more astringent, but has somewhat less of an aromatic flavour. Tinctures drawn from both with rectified spirit, have nearly the same taste; on distilling off the menstruum, the extract left from the tincture of the East-India rhubarb proved considerably the strongest.

Of late, rhubarb has been cultivated in this country with tolerable success, and is found not to be inferior for medical purposes to the foreign.