Hemlock spruce bark is obtained from the trunk and branches of Tsuga canadensis, Carr (Pinus canadensis, Linn.), (N.O. Coniferae), a large tree indigenous to eastern North America, from which most of the outer bark has been removed. The dried bark occurs in pieces of varying size about 5 millimetres thick. The outer surface is usually composed of the remains of the outer bark, and is often of a dull pinkish colour; inner surface striated and yellowish-brown. Fracture fibrous, a smoothed section exhibiting under the lens numerous, scattered groups of sclerenchymatous cells. Odour, slight; taste, strongly astringent.
Constituents.—The chief constituent of hemlock spruce bark is from 8 to 15 per cent. of tannin, but the bark also contains a little resin and volatile oil. The tannin appears to be identical with that of oak bark, and an extract of the bark is used in tanning. A substance resembling Burgundy pitch exudes from the trunk and hardens on the bark; it is known as hemlock or Canada pitch, and used for similar purposes, having rubefacient properties similar to those of Burgundy pitch. It is separated from the bark by boiling with water, and consists of resin with a trace of volatile oil. Hemlock or spruce needle oil contains l-pinene, l-bornyl acetate, and sesquiterpenes.
Action and Uses.—Hemlock spruce bark is used as an astringent in catarrhal diseases of the mucous membranes. A liquid extract is prepared, which is employed as an injection in leucorrhoea, and is given internally in diarrhoea.
- Extractum Pini Canadensis Liquidum, B.P.C.—LIQUID EXTRACT OF HEMLOCK SPRUCE BARK, 1 in 1.
- Used as an astringent injection in leucorrhoea and gonorrhoea, diluted with 10 parts of water. Zinc sulphate may be added to increase the astringency. A colourless variety (distilled) is also obtainable in commerce. Dose.—1 to 4 mils (15 to 60 minims).
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.