Related entry: Resina Draconis.—Dragon's Blood - Myrrha (U. S. P.)—Myrrh

A dry gum-resin obtained from Boswellia Carterii, Birdwood, with its varieties, and several other species of Boswellia.
Nat. Ord.—Burseraceae.
SYNONYMS: Gummiresina olibanum, Thus.
ILLUSTRATION: (Boswellia Carterii) Bentley and Trimen, Med. Plants, 58.

Botanical Source and History.—The individual species of Boswellia yielding this product are not well known. Several trees, possibly distinct species, are classed as varieties of B. Carterii. The genus comprises trees having odd-pinnate leaves, with leaflets serrate, flowers small, 10-stamened, and borne in racemes, and succeeded by 3-celled, drupe-like capsules, each cell of which is 3-seeded. The trees are found in East Africa (Somali country), South Arabia, and India. (For an account of the several species consult Pharmacographia, 2d ed., pp. 133 and 139.) Olibanum is the frankincense of the ancients and was among the offerings of the Magi to the infant Savior. It constituted a large part of the incense so frequently alluded to in the Scriptures. It is collected in the Somali country by making deep incisions into the trunk of the tree from which the milky gum-resin exudes and soon concretes. The clear tears are first gathered, and the portion which has run down the side of the tree or has fallen to the ground, constitutes an inferior sort.

Description.—Olibanum is a translucent, brittle, whitish-yellow substance, in roundish, club-shaped, pear-shaped, or irregular tears, and usually covered by a whitish, farinaceous substance produced by the pieces rubbing against each other. It has a sub-acrid, terebinthinate, bitter taste, and a pleasant, resinous odor, and when burned, it produces a brilliant flame, and diffuses an agreeable aroma. It melts with difficulty, not without decomposition, becomes soft and adhesive by chewing, forms an incomplete, white emulsion when rubbed up with water, and is dissolved by alcohol to the amount of about 65 per cent. It has a specific gravity of 1.22.

Chemical Composition.—Olibanum consists chiefly of an acid resin (56 per cent), soluble in alcohol and having the formula C20H32O4 (Hlasiwetz, 1867); it yields no benzene derivatives when fused with caustic potash. When burned, it emits an agreeable odor. Water removes from it a bitter, viscid substance, little soluble in ether. Olibanum also contains gum (30 to 36 per cent), insoluble in alcohol, and resembles ordinary gum arabic. With 3 parts of water it forms a thick mucilage (Pharmacographia). Finally, olibanum contains about 3 per cent of ash, and from 4 to 7 per cent of a volatile oil. According to Kurbatow (1874), it consists chiefly of a terpene olibene (C10H16), boiling at 158° C. (316.4° F.). Flückiger found it laevo-rotatory, and Wallach (1889) identified it as l-pinene, and in addition found dipentene. Schimmel & Co. also report the occurrence of phellandrene in the oil (Gildemeister and Hoffmann, Die Aetherischen Oele, p. 641).

Action, Medical Uses, and Dosage.—Olibanum is a stimulant, producing results similar to those from the tolu and Peru balsams; it is principally used as a fumigating article, and occasionally forms an ingredient of plasters. The dose, when used internally, is from 5 to 40 grains, in emulsion.

Related Species.—Another gum-resin is obtained from an unidentified tree inhabiting the neighborhood of the Red Sea; it grows upon the bare rocks, without any other support than the very round, thick substance, of a nature between bark and wood, which is thrown out from the base of the trunk, and which adheres very firmly to the rocks. Kempthorne (1843) alludes to this species as being the tree furnishing olibanum.

Boswellia serrata, Roxburgh, is the Boswellia thurifera, Colebrooke, a leafy forest tree of the Coromandel coasts and other parts of India. Though formerly thought to furnish olibanum, this tree is not the source of that drug, but yields a soft odorous resin which slowly hardens within a period of a year, and is used only by the natives as incense.

Boswellia papyrifera, Richard, yields a transparent resin, probably destitute of gum, though thought to contain a volatile oil. It grows in western Abyssinia.

Boswellia Frereana, Birdwood, the Yegaar of the Somalis, yields a fragrant resin of a lemon odor. It contains no gum, and is employed in the East as a masticatory.

Hedwigia balsamifera.—An alcoholic extract of this plant, administered hypodermatically, proved a nerve and cardiac poison. A convulsing alkaloid is contained in it, and a resin capable of lowering the body heat and inducing paralysis (Ann. de Thérap., 1889). (See also p. 1318.)

King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.