Canada Balsam

Canada Balsam is a kind of Turpentine (q.v.) obtained from the Balsam Fir or Balm of Gilead Fir (Abies or Pinus balsamea), a native of Canada and the northern parts of the United States (see FIR). It exists in the tree in vesicles between the bark and the wood, and is obtained by making incisions. It is a transparent liquid, almost colourless, and with an agreeable odour and acrid taste. It pours readily out of a vessel or bottle, and shortly dries up, and becomes solid. When fresh, it is of the consistence of thin honey, but becomes viscid, and at last solid by age. It consists mainly of a resin dissolved in an essential oil, and its composition is approximately: Essential oil, 24 parts; resin, soluble in boiling alcohol, 60; resin, soluble only in ether, 16. Canada balsam was formerly employed in medicine as a stimulant for the cure of mucous discharges, and as a detergent application to ulcers, but it is now rarely used as a remedy. The balsam is much valued for a variety of purposes in the arts—as an ingredient in varnishes, in mounting objects for the microscope, in Photography (q.v.), and by opticians as a cement, particularly for connecting the parts of achromatic lenses to the exclusion of moisture and dust. Its value for optical purposes is very great, and depends not only on its perfect transparency, but on its possessing a refractive power nearly equal to that of glass. See BALSAM.