Next to turpentine oil, the oils of sassafras, wintergreen and birch bark are among the first oils obtained by distillation in the United States. The similarity in odor and taste of birch bark oil with true oil of wintergreen from Gaultheria procumbens was known before 1818.5) The chemical identity of the principal constituent of both, however, was demonstrated by Wm. Procter Jr.6) of Philadelphia in 1843. As the demand for wintergreen oil increased and since wintergreen leaves were not as readily collected, sweet birch bark was distilled indiscriminatly with wintergreen leaves or even distilled alone as substitute7) so that the commercial natural oil is at present obtained almost exclusively from the bark of Betula lenta, L.
1) Dymock, Warden and Hooper, Pharmacographia indica. Part. VI, p. 188.
2) Schimmel's Bericht October 1887, 34.
3) Chem. Ztg. 1*2 (1888), 1338.
4) Journ. f. prakt. Chem. II. 39 (1889), 349.
5) Bigelovv, American Medical Botany. Boston 1818. Vol.2, pp.28 and241.
6) Americ. Journ. Pharm. 15 (1843), 241.
7) Betula lenta and Gaultheria procumbens grow together in the wooded mountainous regions of the North Atlantic states. In a report on the wintergreen oil industry, Kennedy of Pottsville, Pa. (Americ. Journ. Pharm. 54 , p. 49) called attention to the fact that the cost of collection of birch bark was but 17 of that of wintergreen leaves; also that the yield of oil from the bark was about 0.25 p. c, whereas that from wintergreen was 0.80 p. c. According to these figures the cost of production of the oil from birch bark is but half as great as that of wintergreen leaves.