Related entry: Betula
Oil of Birch Tar, Rectified. Oleum Betulae Empyreumaticum Rectifactum. N. F. IV. Rectified Oil of Birch Tar. Rectified Empyroligneous Oil of Birch. Oleum Rusci Rectificatum.—"The pyroligneous oil obtained by the dry distillation of the bark and wood of Betula alba Linné (Fam. Betulaceae), rectified by steam distillation." N. F.
Under this name the National Formulary IV has introduced this oil of tar from the birch. It is, however, not certain whether the rectification has removed some of the valuable constituents. (See Betula.)
It is described as follows:
"Rectified Oil of Birch Tar is a limpid, dark brown liquid having a penetrating, empyreumatic odor resembling that of Russian leather.
"It yields clear solution with 3 volumes of dehydrated alcohol, and with ether, chloroform, glacial acetic acid, amyl alcohol, oil of turpentine, benzene, or carbon disulphide. When mixed with 3 volumes of alcohol or purified petroleum benzin, the solution is not more than slightly turbid but a decided turbidity is produced when mixed with the same volume of methyl alcohol.
"Specific gravity: 0.886 to 0.950 at 25° C. (77° F.).
The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.