(R.T.B., Proc. Linn. Soc, N.S.W., 1898, p. 417, t. XI.) A Stringybark.

Systematic. - A tree attaining a height of from 60 to 100 feet or higher, and a diameter up to 5 feet. Bark dark or black on the outside, fibrous, and longer in the fibre than that of E. IŠvopinea. Branches smooth for a considerable distance down, but this feature varies. Leaves almost identical with those of E. lŠvopinea of this work, and resembling also those of E. obliqua, L'Her. Abnormal leaves broad, rounded at the base, and very acuminate, opposite or nearly so, on a short petiole, the venation well defined, the intramarginal vein being much removed from the edge. Normal leaves lanceolate, falcate, acuminate, often very oblique, shining on both sides, rather thick, the intramarginal vein removed from the edge. Umbels axillary with about eight flowers, peduncle flattened. Calyx tube obconical, stalklet 4 to 6 lines long. Buds longer and larger than those of E. IŠvopinea; operculum hemispherical, shortly acuminate. Anthers reniform, connected above by a prominent connective, valves opening by longitudinal slits. Ovary flat-roofed.

Fruit. - Hemispherical; rim truncate or rounded, occasionally slightly domed, rarely countersunk like E. pilularis, which they closely resemble in shape in some forms; valves slightly exserted ; 4 to 6 lines in diameter.

Habitat. - Originally described from material obtained from Barber's Creek, mostly in the gullies. It, however, extends south as far as Monga, N.S.W.

17 Eucalyptus dextropinea 40

REMARKS.-The fruits and timber are characteristic of this species, and show it to differ distinctly from E. Muellcriana, A. W. Howitt. It is one of the few " Stringvbarks " that has a " sapwood "- a good specific difference. From its specific name it may be thought that the optical character is the only feature that differentiates this tree from its congener, E. IŠvopinea, R.T.B., but such is not the case, and its specific rank, as shown by the above description, is founded on well-defined morphological and other features, as well as on its chemical constituents.

ESSENTIAL OIL. - Leaves and terminal branchlets for distillation were obtained from Barber's Creek, N.S.W., in July, 1898. The yield of oil was 0.85 per cent. The crude oil was red in colour, and had a turpentine-like odour. The presence of volatile aldehydes was not at all pronounced, as it was difficult to even detect them by the odour. Phellandrene was quite absent, and cineol almost entirely so, as it could only be detected in the portion boiling at the most favourable temperature. The oil consisted very largely of a highly dextro-rotatory pinene, and a fair amount of esters. The oil of this species produces a very good turpentine, quite equal to the commercial article.

The crude oil had specific gravity at 150 C. = 0.8778; refractive index at 200 = 1.4684, and was insoluble in 10 volumes 80 per cent. alcohol. The saponification number for the esters and free acid was 22.9.

On rectification about 1 per cent. distilled below 156° C. (corr.). Between 156-162°, 62 per cent. distilled, and between 162-172°, 25 per cent. came over. These fractions gave the following results :-

First fraction, sp. gr. at 150 C.

=

0.8691 ;

rotation aD

+

34.40o

Second

,,

,,

,,

=

0.8759 ;

,,

+

32.46°.

Material of this species for distillation was also obtained in August, 1898, from Currawang Creek, near Braidwood, N.S.W., many miles from the first locality. The oil differed in no respects from the first sample. The yield of oil was 0.83 per cent. The crude oil had sp. gr. at 15° = 0.8758. On redistillation 63 per cent. came over between 156-162°, and 25 per cent. between 162-172°. The specific gravity of the first fraction was 0.860, and of the second 0.8725. The rotation of the first fraction was aD + 32.83°, and of the second aD + 31.7°.

The principal ester in the oil of this species is geranyl-acetate, and in a sample of the oil distilled from material collected at Tallong, N.S.W., in October, 1911, half the total esters in the oil was saponified in the cold with two hours' contact.

The oils from Barber's Creek and Currawang Creek were mixed and preserved in the dark, and in October, 1919, twenty-one years afterwards, the sample was analysed. Very little alteration had taken place in the oil during that period. Between 156-162°, 60 per cent. distilled, and between 162-1726 25 cent. came over. The crude oil and the two fractions gave the following results: -

Plate XVII.

17 Eucalyptus dextropinea 41

W. Marshall, del.

Eucalyptus Dextropinea. R.T.B. A Stringybark

Crude oil, sp. gr. at 150 C.

=

0.8840; rotation aD + 31.0°; refractive index at 200 - 1.4689.

First fraction,

,,

,,

=

0.8670; rotation aD + 31.25°; refractive index at 20° = 1.4651.

Second

,,

"

,,

=

0.8741; rotation aD + 29.80°; refractive index at 20° = 1.4658.

The cineol was determined by the resorcinol method in the oil distilling below 172°. When calculated for the crude oil the result was 6 per cent. The saponification number for the esters and free acid in the crude oil was 17.7. In the cold, with two hours' contact, it was 12 ; after acetylating, the saponification number had increased to 41.3, and in the cold with two hours' contact it was 22, thus showing the presence of some free geraniol.

For further investigation of the terpene, see the article on the "Pinenes of Eucalyptus Oils." For the corresponding laevo-rotatory pinene see under E. IŠvopinea.