/-rt-Pinene has been found in coriander oil, lemon oil, cumin oil, American peppermint oil, and oil of Levant wormseed.

a-Pinene has frequently been found in other oils, but its optical rotation has not been recorded. Thus in Venetian turpentine oil, in the pine tar oil from Finland, in the oil from the leaves and twigs of Larix americana, in Thuja oil, in juniper oil, in the oil from the resin of Callitris verrucosa, in matico oil, in pilea oil, in the oil from Canada snake-root, in boldo leaf oil, in cinnamon root oil, in the oil from Pichurim beans (?), in sassafras oil, the oil from sassafras leaves, in the oils from laurel leaves, massoy bark and Japanese pepper (?), in the oils of bergamot and lemon, in several elemi oils, in oil of myrrh, in the oil from the berries of Schinus molle, in the oils from the following species of Eucalyptus, viz., acmenoides, affinis, aggregata, albens, amygdalina, angophoroides, apiculata, Baeuerleni, bicolor, Bosistoana, Bridgesiana, Cambagei, camphor a, capi-tellata, cinerea, cneorifolia, conica, cordata, corymbosa, crebra, dealbata, dives, dumosa, eugenioides, eximia, fastigiata, Flet-cher/, fraxinoides, Globulus, goniocalyx, gracilis, hemilampra, hemiphloia, intermedia, intertexta, lactea, Iongifolia, Lueh-manniana, Macarthuri, macrorrhyncha, maculata, maculosa, Maideni, melanophloia, melliodora, microcorys, microtheca, Morrisii, nova-anglica, odorata, oleosa, ovalifolia, o. var. lan-ceolata, paniculata, pendula, pilularis, polyanthema, polybractea, populifolia, propinqua, pulverulenta, punctata, p. var. didyma, quadrangulata, radiata, resin if era, Risdoni, robusta, Rossi, rostrata, r. var. boreal is, rubida, saligna, siderophloia, sider-oxylon, s. var. pal lens, Smithii, squamosa, stricta, Stuartiana, tereticornis, tessellaris, trachyphloia, umbra, viminalis, viridis and Woollsiana, in French parsley oil, rosemary oil, sage oil, in the oils of Thymus capitatus and Satureja Thymbra, in oil of spike, in golden rod oil, and in the oil of Helichrysum Stcechas(?).

In as much as a strongly active a-pinene yields little or no nitrosochloride, the formation of this substance is in reality indicative of i-pinene. Since in the above compilation of the occurrence of d- and i-pinene, the presence of pinene in more or less optically active fractions has been established by means of the nitrosochloride reaction, the presence of i-pinene should be assumed. The final determination of the presence of optically active pinene will, therefore, have to rest with the conversion of the optically active pinene into the corresponding optically active pinonic acid. Hence it becomes apparent how desirable it must be to revise the older investigations in the light of the new methods for the identification of pinene. (Comp. p. 297.) a-Pinene is one of the few terpenes that can be obtained in a relatively pure state. It is obtained by heating the solid pinene nitrosochloride with aniline in alcoholic solution.1) The a-pinene thus obtained is always optically inactive and possesses the following physical constants:

B. p. 155 to 156°; d20o) 0,858; nD21o 1,46553.2)

1) Wallach, Liebig's Annalen 252 (1889), 132; 258 (1890), 343. 2) Wallach, Liebig's Annalen 258 (1890), 344.

An a-pinene regenerated from the nitrosochloride in the laboratory of Schimmel & Co. gave the following constants:

B. p. 154,5 to 155°; d15o0,8634; aD + 0; nD20o,46644.

The inactive form was also obtained by the decomposition of pinocamphylxanthogenic acid ester.1) Gildemeister and Kohler2) obtained, upon decomposition of (d-pinocamphylxanthogenic acid ester, active (d-a-pinene, which, however, was rendered impure by the. presence of another terpene.

The strict observation of certain conditions enabled Wallach3) to prepare /-a-pinene from nopinolacetic acid.

Most oils containing pinene presumably contain mixtures of d- and /-pinene. Hence the direction of the rotation in all probability depends on the predominance of the one or the other modification. In order to prepare optically active modifications of a-pinene, it is best to start with pinene fractions possessing a high angle of rotation. It should be borne in mind, however, that this high angle of rotation may be produced by camphene. The fractions boiling below 160° are purified by fractional distillation over sodium until the boiling point and other properties correspond with those of i-a-pinene. The highest angles of rotation thus far observed are the following: for (d-a-pinene from Greek turpentine oil:

[a]D + 48,4° (b. p. 155 to 156°; d25o 0,8542; nD25o 1,4634),4) [a]D + 46,73°(b.p. 156°at760mm; d15o0,8642; nD20o 1,46565),5) for /-a-pinene from the oil of Eucalyptus laevopinea: [a]D19o - 48,63° (b.p. 157°; d 19°16o 0,8626).6)

1) Tschugaeff, Journ. russ. phys. chem. Ges. 39 (1908), 1324; Chem. Zentralbl. 1908, I. 1179.

2) Wallach-Festschrift. Gottingen 1909. p. 436.

3) Liebig's Annalen 368 (1909), 1.

4) Vezes, Bull. Soc. chim. IV. 5 (1909), 932.

5) Gildemeister and Kohler, Wallach-Festschrift Gottingen 1909. p. 434; Report of Schimmel & Co. October 1909, 69.

6) Smith, Journ. and Proceed. of the Royal Soc. of N. S. Wales 32 (1898), 195; Report of Schimmel § Co. April 1899, 24.

a-Pinene is a colorless, mobile liquid, which, like most terpenes, undergoes autoxidation upon standing by taking oxygen from the air and partly resinifies. It is readily converted into other terpenes. Thus by a higher temperature (250 to 270°) it is changed into dipentene, by moist hydrogen chloride into dipentene or its dihydrochloride, by means of alcoholic sulphuric acid into terpinolene and terpinene, presumably through the dipentene as an intermediate stage. Through the action of dry hydrogen halides a-pinene is changed to derivatives of camphor, a reaction that has become of great importance in the artifical production of camphor.