Thus Americanum, B.P. Frankincense.
Frankincense (Terebinthinum, U.S.P. Turpentine) is a concrete oleoresin scraped from the trunks of Pinus palustris, Miller (N.O. Coniferae), and P. Taeda, Linn. When, during the production of turpentine, the flow of the oleoresin gradually ceases, the last portions suffer loss of volatile oil, and solidify before reaching the cavity in which the turpentine collects. This solidified oleoresin constitutes gum thus. When fresh, the oleoresin occurs in soft, pale yellow, opaque, tough nodules, with a marked terebinthinate odour, becoming, on keeping, darker, harder, and more translucent.
Constituents.—It consists of varying quantities of oil of turpentine, together with the resin acids peculiar to colophony.
Uses.—The oleoresin is used in the preparation of plasters (e.g., Emplastrum Picis), and has properties resembling those of resin.