JAlap is the Root of a Plant of four or five Foot high, according to what the Sieur Rousseau and Father Plumier has said of it: The Jalap we now sell is brought to us from New Spain, to which Monsieur Tournefort has not long since given the Name of Solanum Mexicanum magno Flore, Semine rugoso, Jalap existimatum, which signifies the Nightshade of America, with the large Flower, and wrinkled Seed, which is believ'd to be a Species of the Jalap.
Father Plumier will have the said Nightshade to be the Belle de Nuit, because it entirely resembles that which we call in Latin Mirabilis Peruviana. This Plant is very common in our Gardens, and describ'd by Mr. Evelyn by the same Name, and because it only flowers in the Night, it is call'd Belle de Nuit, or the Beauty of the Night.
The Jalap sold in the Shops is brought from the West Indies, but great Quantities of it come from the Maderas, where it grows very common, without Culture. It is reckon'd an excellent Purger of serous and watry Humours, but must be given with Caution, according to the Age and Strength of the Patient, because it works very vigorously, if given in Substance; the ordinary Dose is from a Scruple to a Dram; but that is too large a Quantity for English Constitutions; for if it be good, it will operate sufficiently from half a Scruple to two Scruples, which will answer in the strongest Constitutions.
The Resin or Magistery of Jalap is made with Spirit of Wine, and precipitated with Water, from whence proceeds a liquid Resin, white and gluey, almost like Turpentine, which after it is dried in the Shade, looks like common Resin. It has a fine Smell, like Scammony, and if rightly prepared, when thoroughly dry, is transparent and so brittle, that it will crumble betwixt the Fingers. This is more valuable than the Jalap itself; by reason it is much more efficacious, and can be easier administer'd. The Dose is about five or six Grains, either by itself taken in the Yolk of an Egg, or added in Bolus, Pills, or the like, to make other Physick work quicker and brisker. After the Resin, you may make an Extract by pouring on fresh Spirits of Wine, which will be of a brown Colour, and of the Consistence of Honey, this has the same Effects with the former, but in a less Degree.
Jalap, Jalapium, Gialapa, Gelapo, &c. is a grey Root, full of Resin, which is brought from the West Indies, cut into thin Slices and dried. The Plant which grows from it when in the Ground, is according to Father Plumier and Monsieur Tournefort, a Species of the Belle de Nuit, which the latter calls Jalap officinarum fructu rugoso, the Jalap of the Shops with the wrinkled Fruit. The Stalk grows four or five Foot high; the Leaves are very like those of Ground Ivy, but they are not so thick; the Flower is red as Scarlet, and sometimes changes to yellow and white, very agreeable to the Eye. This Flower blows in the Night, and closes again at the Approach of the Sun, and therefore is call'd Belle de Nuit, or the Night Beauty. Chuse such Jalap as is in the thickest Pieces, streak'd with resinous Veins, hard to be broke with the Hands, but easy to pound in the Mortar; of a grey Colour, the Taste a little acrid; it contains a great deal of Oil and Salt in it: Purges all Humours very well, but chiefly the watry, and therefore is useful in Dropsies, Gout, Rheumatisms, and for Obstructions. All the Names belonging to this Root are taken from the Indians. There are two Sorts of this Jalap, to wit, a whitish, and a blackish or dark brown, which being broke shines a little. This blackish sort is much to be preferr'd, being resinous, and heavier than the other; the whitish has little Resin in it, and therefore not so good, and still less so, if Worm-eaten. It was unknown to the Ancients, not being long since we had it from the West Indies.