JAVAP, a well-known purgative medicine, is the root of exogonium purga, a plant of the natural order convolvulacete. It is found in Mexico, at an elevation of about 6,000 ft. above the level of the sea, in the neighborhood of the town of Jalapa or Xalapa,, from which the name jalap is derived. It is a perennial twining plant, with large flowers and a turnip-like root, varying from the size of a hazel-nut to that of a man's fist. The roots when fresh are white and fleshy, and abound in a milky juice. They are prepared for the market by drying.—Jalap was long erroneously referred to other plants, amongst others viirabilis Jalapa, known in our flower-gardens as marvel of Peru. —The root known as male jalap or he julep, with which the true jalap of commerce is often adulterated, was recently declared by.Mr. Ilartweg to be ipomcsa batatoides. Its properties are somewhat similar to those of true jalap, but it is very inferior.
Map seems to have been first introduced into this country as a medicine about 1609.
The dried roots are brown and wrinkled externally, and of a deep yellowish-gray color internally; theit odor is faint and disagreeable, and their taste is nauseous. The active ingredient is the resinous portion, which varies from about 10 to nearly 20 per cent, and winch is composed of two distinct substances, jalapine and julapic aced. Julep resin may be distinguished from common resin by its insolubility in
volatile oils. Jalap is a valuable cathartic, but is seldom given alone. Its purgative action is increased by the addition of a little calomel, and its .hydragogne actlon by bitartrate of potash, while its tendency to produce griping is obviated by rile addition of a little ginger. It is extremely useful in those febrile affections of children which are associated with constipation; and in diseases of the brain it is a good purgative to select, in consequence of its derivative action. In the form of compound julep powder, which consists of one part of powdered jalap, two parts of bitartrate of potash, and a little ginger, it is of great service in some kinds of dropsy, in consequence of its hydragogue action.
The ordinary dose of powdered julep for an adult varies from 10 to 30 grains, a scrupic generally acting smartly and safely; for children under a year old the dose is front 2 to 5 grains. The dose of the compound powder is double that of the ordinary powder. Tne tincture qf julep, in the dose of 1 or 2 drains, is h useful addition to the ordinary black draught when it is desired to increase its activity.