Hence, while fenchene may not be regarded as one of the constituents of turpentine oil, the presence of camphene can be assumed with relative certainty. The presence of the laevo-gyrate modification of .camphene has been demonstrated by Schimmel &{ Co1) in the following manner. By treating fraction 160 to 161° of American turpentine oil (sp. gr. 0,869; D+1°16') with glacial acetic acid and sulphuric acid according to Bertram's method2) isobornyl acetate was obtained. Upon saponification this yielded isoborneol (m. p. of phenylurethane, 138°). Inasmuch as special experiments demonstrated that neither a-pinene, regenerated from its nitrosochloride, nor -pinene yield iso-borneol when treated according to this method, its formation is attributable to camphene.

The occurrence of cymene supposed by Tilden3) has not yet been proven, neither the presence of limonene in the last fractions of turpentine oil4).

Whether firpene, found by Frankforter and Frary5) in the oil of the Western fir6), is to be regarded as a constituent of normal turpentine oil is doubtful. According to elementary analysis and molecular weight determination, firpene corresponds to the formula C10H16. It differs from pinene in its odor, also in its physical and chemical properties. Its constants are as follows: b.p. 152 to 153,5°; d20 o0,8598; [a]D - 47,2°; nD20 o1,47299. Firpene hydrochloride melts at 130 to 131°, hence has the same melting point as pinene hydrochloride. However it is more volatile and more readily soluble, also has a somewhat different odor. Its principal difference, however, lies in its totally different behavior toward chlorine. Whereas pinene hydrochloride shows no tendency to form a dichloride, firpene hydrochloride readily yields such a compound. .Firpene hydrobromide melts at 102°, pinene hydrobromide at 90°.

1) Report of Schimmel & Co. October 1897, 62.

2) Journ. f. prakt. Chem. II. 49 (1894), 1.

3) Berl. Berichte 12 (1879), 1131.

4) Ahlstrom & Aschan, Berl. Berichte 39 (1906), 1446.

5) Journ. Americ. chem. Soc. 28 (1906), 1461.

6) What species is meant by this designation could not be ascertained. A. L. Brower refers to "western yellow pine" apparently as identical with "long-leaf pine" [Oil, Paint and Drug Reporter 75 (1909), No. 18, p.28f.]. C. Mohr (The timber pines of the Southern U.S.Washington 1897) does not give this synonym.

Toward nitrosyl chloride pinene and firpene behave differently. As is well known, the former yields a well crystallized nitrosochloride without difficultly. From firpene, however, no crystallizable nitrosochloride could be obtained.

Influence of Air and Light on Turpentine Oil. It is a well-known phenomenon that turpentine oil changes rapidly when allowed to stand in open vessels, more particularly in the presence of water. The oil becomes thick, an increase takes place in the specific gravity, index of refraction and boiling point, the optical rotation diminishes, the solubility in 90 p. c. alcohol increases, the originally neutral oil becomes acid and resinifies. Technically it is said to become "rancid"1). Formerly such an oil was designated as being ozonized because it acts strongly as an oxidizing agent.

All of these changes are attributable to slow oxidation by means of atmospheric oxygen. Schonbein2) assumed that the oil became charged with ozone by changing atmospheric oxygen to its active modification. Later it was demonstrated by Kingzett:), d......0,871 1,009

1) After having stood for 7 weeks in stoppered flask partly filled with air, the specific gravity of a normal American turpentine oil had changed from 0,867 to 0,897. It had become soluble in 3,5 vols. of 90 p. c. alcohol whereas originally it required 6 vols. to produce a clear solution.

The specific gravity of another sample of American oil, after prolonged standing, had increased to 0,913 and was soluble in 3 vols. of 90 p.c. alcohol.

After having stood four years in a well stoppered, but not completely filled flask, a French oil revealed the following changes: Original normal oil. The same after four years.

D...... - 29° 55' - 19° 18'

Whereas the original normal oil required 20 vols. of 80 p. c. alcohol to produce a clear solution, the oxidized oil was soluble in 1 vol. of 80 p. c. alcohol, and in all proportions in 90 p.c. alcohol. Compare p. 16, footnote 2.

2) Liebig's Annalen 102 (1857), 133.

3) Journ. chem. Soc. 27 (1874), 511. - Pharmaceutical Journ. III. 5(1874), 84. - Ibidem 6 (1875), 225. - Ibidem 7 (1876), 261. - Ibidem 9 (1879), 772 and 811. - Ibidem 20 (1890), 868. - Chem. News 69 (1894), 143; comp. also Robbins, Pharmaceutical Journ. III. 9 (1879), 748, 792, 872.

Bardsky1) and Papasogli2) that such an oil contains no ozone3) but hydrogen peroxide.

As was first shown by Loew4), other substances than hydrogen peroxide are contained in turpentine oil oxidized in the presence of moisture. Oxidized turpentine oil liberates iodine from potassium iodide, a property not revealed by hydrogen peroxide. As was already assumed by Kingzett5), this action is attributable to traces of organic peroxides. In the presence of water, these finally yield hydrogen peroxide, peroxide hydrates presumably being formed as intermediate products.