This section is from the book "A Research On The Eucalypts Especially In Regard To Their Essential Oils", by Richard T. Baker, Henry G. Smith. Also available from Amazon: A Research On The Eucalypts And Their Essential Oils.
(Sm., Bot. Nov. Holl. 41 (1793), and in Trans. Linn. Soc, iii, 284.) Forest Red Gum.
Systematic. - A tall tree with a smooth bark, although occasionally rough at the base. Abnormal leaves orbicular to broadly lanceolate, 4 inches in diameter and under 6 inches long, sometimes oblique; venation very pronounced on the under side, oblique, spreading, intramarginal vein removed from the edge Normal leaves lanceolate, measuring up to 1 foot in length and over 2 inches in width; venation distinct, spreading, oblique, intramarginal vein removed from the edge. Inflorescence either on axillary peduncles or in terminal panicles. Peduncles flattened, varying in length up to 9 lines, with seven to nine flowers in the umbel. Calyx tube hemispherical, up to 2 lines in diameter, pedicel variable in length, from under 1 line to over 3 lines; operculum conical, up to 5 or 6 lines long, acute or obtuse.
Fruit. - Pedicellate, hemispherical; rim domed; valves well exserted, acute; 2 to 4 lines in diameter.
An easily recognised fruit, with its prominently exserted valves. It more particularly resembles E. rostrata and E. Seeana, than any other species.
Habitat. - Coastal range and districts of New South Wales; Victoria; Queensland; Papua (J.H.M.).
REMARKS. - The type is well defined and widely distributed in Eastern Australia, the broad abnormal leaves, and long, conical operculum being very characteristic.
ESSENTIAL OIL. - Leaves and terminal branchlets for distillation were obtained from Barber's Creek, N.S.W., in June, 1898. The yield of oil was 0.5 per cent. The crude oil was of an orange-brown colour, and had a marked odour of aromadendral. Phellandrene does not appear to occur in the oil of this species, but pinene was present in small amount, cymene was also a constituent of the oil. Cineol was detected, but the amount did not exceed 10 per cent. in the first fraction. Esters occur in some quantity. Aromadendral was a pronounced constituent in the third fraction, from which it was isolated in a pure condition, and its chemical compounds prepared. The oil of this species was almost identical with that obtained from the variety didyma of E. punctata; it has little commercial value at present.
The crude oil had specific gravity at 150 C. = 0.9218; rotation aD - 9.4°; refractive index at 20° = 1.4877, and was soluble in 1 volume 80 per cent, alcohol. The saponification number for the esters and free acid was 26.7.
On rectification, 2 per cent. distilled below 1690 C. (corr.). Between 169-183°, 48 per cent, distilled; between 183-224°, 26 per cent. came over, and between 224-240°, 10 per cent. distilled; leaving 14 per cent. boiling above 240° C, which consisted largely of the sesquiterpene. The fractions gave the following results: -
First traction, sp. gr. at 15 C.
The light did not pass well with the third traction, but it was strongly lævo-rotatory. The figures show the presence of a considerable amount of aromadendral.
In July, 1910, material of this species was received from near Parramatta, N.S.W., forwarded for distillation by Dr. Cuthbcrt Hall. The yield of oil was 04 per cent. The crude oil was in agreement with that from Barber's Creek, and contained similar constituents in about the same amounts. Cineol did not exceed 10 per cent.
The crude oil had specific gravity at 15° C. = 0.9158; rotation aD - 11.8°; refractive index at 20° = 1.4906, and was soluble in 1 volume 80 per cent. alcohol. The slightly higher rotation was due to an increased amount of aromadendral.