Uses—Stick liquorice is sucked as a remedy for coughs, and by children as a sweetmeat. It is also used in lozenges, and in some pharmacopœias is admitted as the raw material from which to prepare soft extract of liquorice.
The block liquorice, of which a large quantity is imported, is chiefly used in the manufacture of tobacco for smoking and chewing.
OLEUM ARACHIS.
Ground-nut oil, Earth-nut oil, Pea-nut oil, Arachis oil; F. Huile d’Arachide ou de Pistache de terre; G. Erdnussöl.
Botanical Origin—Arachis hypogæa L., a diffuse herbaceous annual plant, having stems a foot or two long, and solitary axillary flowers with an extremely long filiform calyx-tube. After the flower withers, the torus supporting the ovary becomes elongated as a rigid stalk, which bends down to the ground and forces into it the young pod, which matures its seeds some inches below the surface. The ripe pod is oblong, cylindrical, about an inch in length, indehiscent, reticulated, and contains one or two, or exceptionally even four irregularly ovoid seeds.
The plant is cultivated for the sake of its nutritious oily seeds in all tropical and subtropical countries, but especially on the west coast of Africa. It is unknown in the wild state. De Candolle[738] regards it as a native of Brazil, to which region the other species of the genus exclusively belong. But the opinion of one of us[739] is strongly in favour of the plant being indigenous to Tropical Africa, and so is that also of Schweinfurth. Arachis is one of the most universally cultivated plants throughout Tropical Africa, from Senegambia to lake Tanganyika. In Europe it has not proved remunerative.
History—The first writer to notice Ground-Nut appears to be Fernandez de Oviedo y Valdes, who lived in Hayti from a.d. 1513 to 1525; he mentions in his Cronica de las Indias[740] that the Indians cultivated very much the fruit Mani, a name still used for Arachis in Cuba and in South America. A little later, Monardes,[741] described a nameless subterraneous fruit, found about the river Maranon and held in great esteem by both Indians and Spaniards. But before, the French colonists sent in 1555 by Admiral Coligny to the Brazilian coast had become acquainted with the “Mandobi,” which Jean de Léry[742] described quite unmistakably. Good accounts and figures of it were given in the following century by Johannes de Laet (1625),[743] and by Marcgraf,[744] who calls it by its Brazilian name of Mundubi. It is enumerated by Stisser among the rare plants cultivated by him at Helmstedt (Brunswick), about the year 1697.[745]
It is only in very recent times that the value of the Ground-Nut has been recognized in Europe. Jaubert, a French colonist at Gorée near Cape Verde, first suggested about 1840 its importation as an oil-seed into Marseilles, where it now constitutes one of the most important articles of trade.[746]
Description—The fat oil of Arachis, as obtained by pressure without heat, is almost colourless, of an agreeable faint odour and a bland taste resembling that of olive oil. An inferior oil is obtained by warming the seeds before pressing them. The best oil has a sp. gr. of about 0·918; it becomes turbid at 3° C., concretes at -3° to -4°, and hardens at -7°. On exposure to air it is but slowly altered, being one of the non-drying oils. At length it thickens considerably, and assumes even in closed vessels a disagreeable rancid smell and taste.
Chemical Composition—The oil consists of the glycerides of four different fatty acids. The common Oleic Acid, C₁₈H₃₄O₂, that is to say its glycerin compound, is the chief constituent of Arachis oil. Hypogæic Acid, C₁₆H₃₀O₂, has been pointed out by Gössmann and Scheven (1854) as a new acid, whereas it is thought by other chemists to agree with one of the fatty acids obtained from whale oil. The melting point of this acid from Arachis oil is 34-35° C. The third acid afforded by the oil is ordinary Palmitic Acid, C₁₆H₃₂O₂, with a fusing point of 62° C. Arachic Acid, C₂₀H₄₀O₂, the fourth constituent, has also been met with among the fatty acids of butter and olive oil, and, according to Oudemans (1866), in the tallow of Nephelium lappaceum L., an Indian plant of the order Sapindaceæ.