This section is from the book "A Text Book Of Materia Medica, Being An Account Of The More Important Crude Drugs Of Vegetable And Animal Origin", by Henry G. Greenish. Also available from Amazon: A Text Book of Materia Medica : Being an Account of the More Important Crude Drugs of Vegetable and Animal Origin.
Olibanum or, as it is sometimes termed, frankincense (to be carefully distinguished from American frankincense) is a gum-resin obtained from Boswellia Carterii, Birdwood, and other species of Boswellia (N.O. Burseraceoe).
These plants are small trees that grow in southern Arabia and in Somaliland. Like the trees that yield myrrh they contain schizogenous ducts in the bark, in which an oleo-resin is secreted. The Somalis incise the bark and collect the gum-resin as soon as it has sufficiently dried. The drug is conveyed to Aden and thence to Bombay, whence it is exported to Europe.
Olibanum occurs in small tears varying from 0.5 to 3 cm. in length and usually ovoid, pear-shaped, or club-shaped, but sometimes stalactitic in form, occasionally agglutinated into small masses. They are usually of a pale yellowish colour, frequently with a greenish, bluish, or reddish tinge, semi-translucent and covered with a dull white dust, the surface of the tear being dull even after the dust has been removed. They are brittle, breaking easily between the fingers; internally they are opalescent and translucent, the fractured surface being dull and waxy.
The drug has a fragrant, balsamic odour and an aromatic, slightly bitter taste, and soften to a plastic mass when chewed. Triturated with water it yields a whitish emulsion.
The student should observe
(a) The fragrant odour,
(b) The opalescent, waxy interior of the tears.
These constituents have been further investigated, with the following results (Halbey, 1898):
Soluble in alcohol, 72 per cent.
'Boswellic acid, free .
,, „ combined
Insoluble in alcohol, 28 per cent.
Gum (arabic acid with Ca and Mg)
According to this analysis the resin consists principally of a resin acid (boswellic acid) and an indifferent resin (olibano-resene) in about equal proportions. The gum consists mainly of arabin, with which is associated a little bassorin. The volatile oil is yellowish and fragrant; it contains pinene, dipentene, and phellandrene, but the aromatic constituent is not yet known.
Olibanum is used chiefly in the manufacture of incense and as an ingredient in plasters and fumigating pastilles.