The second quality, which was introduced into commerce is great quantities a few years ago, by the name of stalk jalap, is now more scarce, and obtained from the Ipomoea orazabensis of Pelletan, a plant growing without cultivation in the neighbourhood of the Mexican town of Orizaba.  The root, as met with in the trade, consists of pieces varying from one to three inches in length, and 11/2 to two inches in diameter.  They are of a higher color than the first-named root, and of decidedly fibrous structure.  The chief constituents of both varieties is a peculiar resin, of which they contain about 10 per cent.

Scammony.—­The root of Convolvulus Scammonia, another plant of the same family, affords, when cut, a gummy resinous exudation or milky juice, which soon concretes and forms scammony.  The plant grows abundantly in Greece, the Grecian Islands, and various parts of the Levant.  It is imported from Aleppo in drums, weighing from 75 to 125 lbs. each, and from Smyrna in compact cakes like wax packed in chests.  In 1839, the quantity on which duty (2s. 6d. per lb.) was paid amounted to 8,581 lbs.  The duty received for scammony, in 1842, was L607.  A spurious kind is prepared from Calystegia (Convolvulus) sepium, a native of Australia, and several plants of the Asclepiadacae order.

Dr. Russell ("Med.  Obs. and Inqui.”) thus describes the mode of procuring scammony:—­

Having cleared away the earth from the upper part of the root, the peasants cut off the top in an oblique direction, about two inches below where the stalks spring from it.  Under the most depending part of the slope they affix a shell, or some other convenient receptacle, into which the milky juice flows.  It is then left about twelve hours, which time is sufficient for the drawing off of the whole juice; this, however, is in small quantities, each root affording but a few drachms.  This milky juice from the several roots is put together, often into the leg of an old boot, for want of some more proper vessel, when in a little time it grows hard, and is the genuine scammony.  Various substances are often added to scammony while yet soft.  Those with which it is most usually adulterated are wheat flour, ashes, or fine sand and chalk.

Liquorice.—­The plant which yields the liquorice root of commerce is Glycirrhiza glabra or Liquiritia officinalis.  It is a native of Italy and the southern parts of Europe, but has been occasionally cultivated with success in Britain, especially at Pontefract, in Yorkshire, and at Mitcham, in Surrey.  The plant is a perennial, with pale blue flowers.  It grows well in a deep, light, sandy loam, and is readily increased by slips from the roots with eyes.  The root, which is the only valuable part, is long, slender, fibrous, of a yellow color, and when grown in England is fit for use at the end of three years.  The sweet, subacid, mucilaginous juice is much esteemed as a pectoral.  It owes its sweetness to a peculiar principle called glycrin or glycirrhiza, which appears also to be present in the root and leaves of other papilionaceous plants, as G. echinata and glandulifera, Trifoliwm alpinum, and the wild liquorice of the West Indies, Abrus precatorius, a pretty climber.