The dose of scammony is from grs. v. to grs. xvj.; whether it be given in powder, or as a bolus, or in the form of mixture, triturated with almonds, gum, or extract of liquorice, and water.

Officinal preparations.-Confectio Scammonii, L. Electuarium Scammonii, D. Pulvis Scammonii comp. L. E. Extractum Colo-cynthidis comp. L. D.

2. Ipomcea Jalapa. Officinal. Jalapa, Lond. Convolvuli Jalapae radix, Edin. Dub. Jalap root.

Syn. Jalap (F.), Jalappenharz (G), Jalapparot (Swed.), Scialappa (I.), Jalapa (S.).

The plant yielding jalap is a native of America, taking its name from Xalappa, a city of Mexico. The researches of Dr. Redman Coxe, of Philadelphia, have ascertained that it is an Ipomoea: Dr. Coxe has named it Ipomoea Jalapa.1 It grows in a dry sandy soil, and flowers in August and September. The tuber is perennial, of an irregular egg-shape, externally of a dark brown colour, internally white, and, when fresh, abounding with a milky juice. It sends up many twining, round, twisted stems, of a light brown hue, which extend upwards of twenty feet, with smooth petiolated leaves, of a bright green colour, varying in shape, the upper being cordate, the lower angular, nearly hastate, oblong and pointed. The under surface of all the leaves is prominent and veined; and all are supported on foot-stalks the length of the leaf. The flowers are borne on axillary peduncles that send off two or three pedicels, each bearing a large, funnel-shaped, entire, plaited flower, of a lilac purple colour : with a calyx composed of five oval, concave, obtuse, pale green leaves, without bractes.

The anthers are white, large, on long slender filaments; the style is longer than the filaments, the stigma capitate and simple, and the germen oval.2

The root of this plant, which is the jalap of the shops, was first brought to Europe about the year 1609 or 1610.3 The best comes from Vera Cruz in transverse slices, and also in egg-shaped, pointed, entire tubers, covered with a very thin, wrinkled, brown cuticle. That which is sliced is more liable to be adulterated, which is said to be sometimes done with slices of briony root; but the fraud is easily discovered by the spongy texture and whiter colour of the latter, and its burning less readily when applied to the flame of a candle,

1 It is said to have been cultivated in England by Mr. Miller in 1668; and that a few years ago two specimens were in vigorous growth in Kew gardens, slips of the original plant introduced there by Mons. Thouin in 1778; but that these were the true jalap is doubtful.

A root of Ipomoea Macrorhiza, supposed to be the true jalap, was carried by Michaux, junior, in 1803, from the Botanic gardens of Charlestown to Paris, and planted there in the garden of the Museum of Natural History, where it now grows : it weighed 47 pounds and three quarters.-Memoires de l'Institut, torn. vi. 387.

2 Observations on the jalap plant, by John Redman Coxe, M. D., p. 9. I take this opportunity of publicly thanking Dr. Coxe for his polite attention in sending me a live tuber of the true jalap plant. It is remarkable that the College of Physicians should have referred to a MS. of Professor Don, in the present edition of the London Pharmacopoeia, when Dr. Coxe's pamphlet has been before the profession since 1830.

3 Baukin Prodromus, 135.

Qualities.-Good jalap root has a sweetish, heavy odour when broken, and a sweetish, slightly pungent taste. It is heavy, compact, and hard, with a shining resinous fracture, which shows the internal part of a yellowish grey colour, interspersed with deep brown concentric circles. It is pulverulent, affording a powder of a pale brownish-yellow colour. Both water and alcohol, separately, extract a part; and when mixed, take up the whole of the active constituents of jalap, Ether dissolves three parts of ten submitted to its action; and affords, when evaporated over water, a transparent insipid resin, and some extractive; but, according to Cadet, the ether takes up only a soft resin, and leaves a hard resin. Hence jalap appears to contain a soft and a hard resin, starch, extractive, and ligneous matter.1 M. Henry gives the following as the result of his examination of several specimens of jalap found in France:-~

Extract.

Resin.

Residue.

Jalap leger, -

75

60

270

sain, -

140

48

210

pique, -

125

72

200

Medical properties and uses-Jalap is a stimulant cathartic, acting briskly on the bowels; and although occasionally griping severely, yet safe and efficacious, It is used in the same cases as scammony, whenever it is required effectually to evacuate the intestines; and as a hydragogue purgative it is supposed to possess singular efficacy. It has been asserted that it proves hurtful in hypochondriasis, bilious habits, and fevers, except of the intermittent kind; but Dr. Hamilton used it in all these instances, in typhus, and the exanthemata, with the best effects.2 The watery extract purges moderately without griping, and is therefore well adapted for children; but the alcoholic scarcely at all purges, although it occasions the most violent tormina and gripings. It is frequently triturated with hard sugar, which renders its powder finer, and increases its activity; and with other cathartics, especially sulphate of potassa, by which the action of both is reciprocally improved. In dropsical affections, the bitartrate of potassa is a useful addition; and in the cachexias and worms it may be united with calomel, the operation of which it greatly quickens.

1 Mr. Hume supposed he had discovered a peculiar principle in jalap, which he termed Jalapine; but his experiments require to be confirmed,-Lond. Med, & Phys. Journal, April 1824.

2 Observations, etc. on Purgative Medicines, 8vo. passim.

The dose is from grs. x. to 3 ss. in powder, pills, or bolus; with a drop or two of essential oil to prevent griping.

Officinal preparations.-Pulv. Jalapce comp. L. E. Pulvis Scant" monii comp. L. Extractum Jalapae, L. E. D. Tinctura Jalapae, L. E. D. Tinct. Sennae comp. E.