During the systematic investigation of the various Eucalyptus oils recorded in this work, it was found that pinene is a most pronounced constituent in certain species, the greater portion of several of them consisting of that terpene.

The species from which it is possible to distil an oil similar in character and composition to ordinary "turpentine" were, at the time of their investigation, scientifically undescribed, and in order to distinguish the two principal pinene yielding species, it was decided to apply the names E. dextropinea and E. Icevopinea to them respectively,* so as to clearly indicate the location of either the dextro- or laevo-rotating pinene, and also to point out from which Eucalyptus species the two optically active forms of "turpentine" could be distilled. Other species, such as E. phlebophylla and E. Wilkinsoniana, might also be mentioned in this connection.

Coniferous trees from which an oleo-resinous exudation, suitable for "turpentine" production, could be derived, hardly occur in Australia, and it is only from one tree (Agathus robusta) the "Queensland Kauri," that it would be possible to prepare "turpentine" commercially,† The resinous latex of this tree contains about 14 per cent. of terpenes corresponding in composition to ordinary turpentine, but unfortunately the trees are too sparsely distributed and too few in number to enable an industry to be established in this way, even if other conditions did not operate adversely.

If it is desired, therefore, to produce Australian "turpentine" from indigenous trees, other sources of supply must be sought, and to this end we suggest the above species of Eucalyptus for this purpose. By the application of modern methods of scientific cultivation it might be possible to bring about increased production of oil in the leaves, and thus secure a greater yield of oil than is obtainable from the leaves of mature trees at the present time. The establishment of a "turpentine" distilling industry in Australia from the Eucalypts might thus be made possible. A point in its favour is that the crop of leaves would be constant and the trees not killed as obtains in America.

* In this naming of species on a chemical constituent we follow Smith in Trans. Linn. Soc, III, 286 (partly), who, soon after the foundation of Australia, named the "Sydney Peppermint," Eucalyptus piperita, on account of certain constituents in the oil, as indicated by the odour, † See Research on the Pines of Australia, Baker and Smith, p. 386. (Technical Education Series, No. 16.)

The sources of supply of commercial turpentine have for a long time been slowly decreasing, while the demand has, at the same time, risen greatly. The supply of "turpentine" in the United States is slowly being exhausted, and statistics show that the demand has increased over go per cent. during very recent years. The question is thus of considerable commercial importance, not only to Australia but to the world generally.

To meet this demand it should be possible to procure quickly and continually supplies from plants of the pinene yielding Eucalypts grown from seed, and systematically treated similarly to other crops. Probably four to five years would be ample to produce a sufficient growth of leaf, and the oil from this young material would agree in composition with that obtained from the leaves of older trees, while generally the yield would be greater. In comparison with the slow growth of Coniferous trees for "turpentine" production, the advantage is altogether with the Eucalypts.

Mature trees of E. dextropinea have already yielded us 1 per cent. of oil, over 90 per cent. of which corresponded to ordinary turpentine. The residues from the rectified oil would also be of value, particularly as a considerable proportion consists of geranyl-acetate and free geraniol.

Although it would hardly pay to undertake the manufacture of "turpentine " from mature trees of these two species, as they grow to a large size, yet, if they were cultivated it should be possible to produce turpentine cheaper than it is now being landed from America.

It appears, therefore, that it is to the Eucalypts that we must look to provide the necessary supplies of turpentine in the future. (See also the article on the Pinenes of Eucalyptus Oils.)