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.
Canada turpentine is an oleo-resin obtained by incision from the balsam fir, Abies balsdmea, Miller, and the hemlock spruce, A. canadensis (Linne), Miller (N.O. Conifeoe), trees widely distributed over the northern United States and Canada, extending to Hudson's Bay. The drug, which has long been known, is collected in Lower Canada, especially in the province of Quebec.
The tree contains schizogenous oleo-resin ducts, as most Coniferous trees do, but they are restricted to the bark, none occurring normally in the wood. In addition, however, to these secretion ducts, cavities are formed which fill with oleo-resin and produce blisters on the smooth trunk of the tree. From these blisters the oleo-resin is obtained by puncturing them with the pointed spout of a can which serves to receive the turpentine.
Canada turpentine is a clear, transparent liquid, about as viscid as honey, and of a pale yellow or greenish yellow colour, often exhibiting a slight greenish fluorescence. By keeping it becomes more viscid, and finally it gradually dries to a hard resin which remains transparent and shows little disposition to crystallise, a quality that renders it particularly valuable as a medium in which to preserve microscopical preparations. It has an agreeable balsamic odour and a rather bitter and acrid taste. It is completely soluble in chloroform, benzene, and ether, but only partially in alcohol.
Canada turpentine consists approximately of 16 to 24 per cent, of volatile oil mixed with from 70 to 80 per cent, of resin.
The volatile oil consists chiefly of l-pinene.
Of the resin about 20 per cent, is composed of an indifferent resene, canado-resene, which is remarkable for its insolubility in alcohol. A further 20 per cent, of the resin is amorphous canadinic acid. The remaining 60 per cent, consists of two amorphous resin acids, a- and β-canadinolic acids, associated with 0.5 per cent, of crystalline canadolic acid.
The bitter principle, which is soluble in water, has not yet been isolated.
Canada turpentine is extensively used as a microscopic mountant. For this purpose the resin, obtained by heating the turpentine until the volatile oil is driven off, is dissolved in xylol, or some other suitable solvent. It is also used for cementing lenses.
Oregon balsam is a similar oleo-resin obtained from Abies Menziesii, Lindley, on the Pacific slope; it is thinner than Canada balsam and yields a sticky film on evaporation.