The flow of juice from incisions in the bark is much less than in most of the species, but at the time of late maturity a spontaneous exudation partly evaporates, hardening on the bark, which is stripped, broken in pieces, and boiled in water. The melted pitch is skimmed off and boiled for a second time. The product is of a dark reddish-brown colour, brittle, hard, opaque, almost tasteless, and with a very slight odour. It melts and softens at a low temperature.
An extract of the bark is used in tanning.
Constituents :
Besides resin, there is found a volatile oil, oil of spruce or oil of hemlock, and tannin.
Uses :
Canada Pitch is softer than Burgundy Pitch, so that even the temperature of the body makes it inconvenient to handle. It is a mild rubefacient. The liquid extract has been used as an astringent. It resembles rhatany in its action.
The volatile oil is used in veterinary liniments, and to procure abortion, but it is very dangerous for this purpose.
Hemlock or Canada Pitch Plaster can be made by melting together go parts of Canada Pitch to 10 parts of Yellow Wax, straining and stirring until it cools and thickens.
