Glycyrrhiza glabra. Liquorice.
Nat. Ord. — Fabaceae, or Leguminosae. Sex. Syst. — Diadelphia Decandria.
Description. — The liquorice plant has a perennial, cylindrical root, running to a considerable length and depth, grayish-brown externally, yellow internally, succulent, tough, pliable, rapid in its growth, and furnished with scattered fibers. The stems are erect, herbaceous, smooth, striated, with few branches, of a dull, glaucous-gray color, and growing two or three feet in night. The leaves are alternate, unequally pinnate ; the leaflets are generally about thirteen, one terminal, ovate, somewhat retuse, petiolate, of a yellowish-green color, and viscid on their under surface ; stipules inconspicuous. The flowers are small, bluish or purplish, and are arranged in axillary, erect spikes, shorter than the leaves, and supported on long peduncles. The calyx is persistent, tubular, bilabiate, and five-toothed. The corolla consists of an ovate, lanceolate, obtuse, erect vexillum, two oblong alae, and a two-parted, straight carina. The stamens are diadelphous ; the anthers simple and rounded. The ovary is short, with a subulate style and blunt stigma. The legumes are oblong, smooth, compressed, acute, and one-celled, containing two or three small, reniform seeds.
History. — This plant is a native of the south of Europe and Asia, and is cultivated in England, France, and Germany. The root is imported chiefly from Messina and Palermo in Sicily, and some considerable from Spain. The root is the officinal part; when dry it is in long pieces, varying in thickness from a few lines to more than an inch, wrinkled longitudinally, grayish-brown on the surface, so dense as to sink in water, yellow, fibrous, and tough in its substance, without odor, and of a strong, peculiar, sweet, mucilaginous taste, and sometimes with a slight degree of acrimony. Its powder is brownish-yellow, or pale-yellow, if made of decorticated root. It must be kept in a dry place, or it will spoil. Its active part is soluble both in water, and in alcohol. A concentrated watery solution is acidulous. The best pieces are those not decayed or worm-eaten, with an internal bright-yellow color, and distinct layers. Analysis has found in it, Glycyrrhizin or Glycion; agedoïte, a crystallizable principle identical with asparagin ; starch ; albumen ; a brown acrid resin ; a brown azotized extractive matter ; lignin ; salts of lime and magnesia, with phosphoric, sulphuric and malic acids.
Glycyrrhizin may be obtained by subjecting a strong cold infusion of the root to ebullition, in order to separate the albumen ; then filtering, precipitating with acetic acid, and washing the precipitate with cold water to remove any adhering acid. By solution in alcohol, and evaporation by a very gentle heat, it may be still further purified. It is a peculiar, transparent, yellow substance, of a sweet taste, hardly soluble in cold water, very soluble in boiling water, but forming a jelly with it on cooling, precipitated from its aqueous solution by acids, readily soluble in cold alcohol, does not undergo vinous fermentation, yields no oxalic acid by the action of the nitric, and is, therefore, distinct from sugar. In combination with the alkalies it retains its sweetness. Carbon, hydrogen, and oxygen are its elementary constituents.
An extract of sugar of liquorice, (Extractum Glycyrrhizae), comes from Spain, Italy, and Sicily, in the form of hard, black cylinders, which is prepared by inspissating the decoction in copper kettles, till the mass is thick enough to become firm on cooling. The finest kind comes from Italy, and is stamped with the maker's name, "Solazzi." Water slowly dissolves from three-fifths to eleven-twelfths of it, alcohol only about one-eighth, and acquires an acrid taste, while the residuum is purely sweet, and entirely soluble in water.
The crude extract of liquorice is in cylindrical rolls, somewhat flattened, about five or six inches in length, by an inch in diameter, and often covered with bay leaves. The best kind is very black, dry, brittle, having a shining fracture, and a peculiar, sweet taste, and is nearly completely soluble in water. It frequently contains impurities, and should be purified previous to internal administration. A good extract, but less hard and brittle than the foreign, and more soluble in water, is prepared in New York.
To purify liquorice, the crude extract is dissolved in water without boiling, the solution strained, and evaporated to the proper consistence. Sometimes gum, glue, or starch is added during the process. Before the extract becomes perfectly dried it is rolled into long cylindrical pieces about the thickness of a pipe-stem, and is called Refined Liquorice. If the water be boiled during the purification, much of the impurity may be taken up, as well as the acrid oleo- resinous substance of the liquorice, which is not desirable.
The Glycyrrhiza Lepidota, which grows in Missouri, possesses the taste of liquorice to a considerable degree.
Properties and Uses. — Liquorice is a demulcent and expectorant, and is very useful in catarrhal affections, cough, and irritations of mucous membranes, allaying irritation of the urinary organs, and the pain in diarrhea. The decoction is the best form of administration, which may be given alone, or in combination with other agents. Before being used, it should always be deprived of its acrid bark. Long boiling extracts the acrid resinous principle ; hence, in making a decoction, for the purpose of sweetening diet-drinks, or covering the taste of nauseous drugs, it should be boiled for only a few minutes. Probably, upon this acrid principle depends its virtues in chronic bronchial affections. The powdered root is also employed to give due solidity to pills, and to prevent their adhesion to each other ; the extract, for imparting the proper viscidity to them. The extract held in the mouth, and allowed slowly to dissolve, is very useful in allaying cough. An excellent troche or lozenge very useful in ordinary cough, may be made by combining together, six parts of refined liquorice, two parts of benzoic acid, four parts of pulverized alum, and half a part of pulverized opium. Dissolve the liquorice in water, and evaporate to the proper consistence, then add the powders with a few drops of oil of anise, and divide into three or six grain lozenges.
Off. Prep. — Confectio Sennae; Decoctum Glycyrrhizae ; Extractum Glycyrrhizae ; Tinctura Aloes.