Origin. The so-called Oregon balsam, which closely resembles the Canada balsam, was first mentioned in pharmaceutical literature in 18711). It is obtained principally from the Douglas fir, Pseudotsuga Douglasii, Carr.2) (Pseudotsuga mucronata, Sudworth; Ps. taxi folia, Carr., Tsuga Douglasii, Carr.), a conifer that is widely distributed in the Rocky Mountains and in the mountains of California and Oregon. With the exception of the darker color, Oregon balsam resembles Canada balsam in appearance. According to Rabak, the sp. gr. lies in the neighborhood of 1 (0,993 to 1,01). The balsam is slightly lasvogyrate or dextrogyrate ( - 3° to +4°). Distilled with steam it yields 22 to 25 p. c. of volatile oil. According to G. B. Frankforter3), the turpentine is liquid at 15° and solid at 0°; d20 o 9821; [a]D-8,82°; nD20o1,51745.
From the oleoresin of Pseudotsuga taxi folia, W. C. Blasdale4) obtained 9 p. c. of oil; d 0,8583; aD - 41°21'; nD 1,4754; which distilled principally between 157 and 160°.
The American firs Abies concolor, Lindl., A. nobilis, Lindl. and A. amabilis, Forb. yield similar oleoresins. According to Rabak5) the properties of the balsam of A. amabilis are: d22o 0,969; color light yellow; optically inactive; yield of oil 40 p.c.
Properties. According to Rabak, Oregon balsam oil has a pleasant turpentine-like odor and distils over principally between 150 and 160°; d 0,822 to 0,882; aD - 34 to - 40°. Frankforter observed the following constants: d20o 0,8621; [a]D - 47,2°; 47,20o; nD1,47299.
The oil of Abies amabilis has a lemon-like odor and distils between 160 and 190°; d22,0,85; aD - 12° 17'.
Composition. According to Rabak, the bulk of the Oregon balsam oil consists of /-a-pinene (m. p. of nitrosochloride 106°; of nitrosopinene 125°).
1) Rabak, Pharm. Review 22 (1904), 293.
2) The numerous synonyms of this tree are recorded by Rabak loc. cit.
3) Journ. Americ. chem. Soc. 28 (1906), 1467.
4) Journ. Americ. chem. Soc. 23 (1901), 162. - Pharm. Review 25 (1907), 363. 5) Pharm. Review 23 (1905), 46.
According to the same investigator, the oil of A. amabilis consists of several terpenes: the lower boiling fraction of a-pinene (probably /-) (m. p. of nitrolbenzylamine 121°), the higher boiling fractions probably of /-limonene (m. p. of nitrolbenzylamine 97° in place of 93°).
If the distillate of the Douglas fir (Pseudotsuga Douglasii, Carr.) is distilled with low tension steam until all of the turpentine oil has passed over, there remains a viscid, yellow oil, "fir oil", which according to Benson and Darrin 1) possesses the following constants: m. p. - 40°; [a]D20o - 37,6°; n20o. 1,4818; solubility in 70 p.c. alcohol 49:100; a. v. 1,55; S. V. 11,1; Iodine V. 185. From its composition, its behavior when fractionated, and from the ready formation of terpin hydrate when treated with 5 p. c. sulphuric acid, the authors conclude that at least one-third of the oil consists of terpineol.