(F.v.M. with E. sideroxylon in Trans. Vic. Inst., I, 33, 1855.)

White Gum

Systematic.-A moderately sized tree seldom exceeding 20 to 30 feet, with a smooth bark. Bark deciduous, whilst in young trees it is yellow or reddish in colour. Abnormal leaves ovate to ovate-lanceolate, sessile or shortly petiolate, often glaucous. Normal leaves ovate-lanceolate to narrow lanceolate, often thickish; intramarginal vein removed from the edge; venation oblique, sometimes 6 inches long and under 1/2 inch wide. Buds usually two to three each on a slender pedicel about 5 lines in length, as long or longer than the common axillary peduncle. Calyx tube broadly conical, or semi-ovate; operculum almost the same length as calyx tube, sometimes shorter, acuminate.

Fruit. Truncate or hemispherical, semi-ovate; rim countersunk after the primary one has become detached; valves not exserted; about 5 lines long and 4 lines broad.

Morphologists have failed to distinguish these from E. sideroxylon, so that the two trees were often confounded by systematists from herbarium material. The hemispherical forms come closely to those of E. pilularis.

Habitat. Victoria and South Australia.

REMARKS. The systematic position of this species seems now to l>c firmly established, owing principally to the perspicacity of Dr. Woolls. He describes (ally, Proc . Linn. Soc. N.S.W., vol. xi, 1886, p. 859, the differences between this species and its congener E. sideroxylon with which, on moq>hological grounds, it had been confounded in the past. The two are quite distinct in most physical characters, except the fruits, which are uncommonly alike.

ESSENTIAL OIL. - Material consisting of the leaves and terminal branch-lets was forwarded for distillation from the Kingscote end of Kangaroo Island, in June, 1911. This species grows somewhat plentifully on Kangaroo Island, and is stated to have both red and white flowers. It seems to be generally known throughout the island as " Blue Gum."

The leaves, after steam distillation, were quite red in colour, resembling in this respect those of the "Red Mallee," and a few other species. The yield of oil was 0.78 per cent. The crude oil was reddish in colour, due to the influence of iron from the still acting on the phenols. The odour was that given by oils belonging to the cineol-pinene class, and volatile aldehydes were pronounced. No indication was given for the aldehyde aromadendral. Phellandrene does not occur in the oil of this species. The terpenes present were pinene and limonene; probably cymene occurs also. A fairly large fraction was obtained boiling above 260o, which consisted principally of the sesquiterpene. The amount of esters was small.

The crude oil had specific gravity at 15o C. = 0.8987; rotation aD + 9.2°, refractive index at 20o - 1.4711; and required 1 volume of 80 per cent. alcohol to form a clear solution. The saponification number for the esters and free acid was 3.8.

On rectification a few drops of acid water, together with some aldehydes, came over below 165o C. (corr.). Between 165-172o, 34 per cent, distilled; between 172-225o, 50 per cent, came over, and between 225-276o, 13 per cent. distilled. These fractions gave the following results :-

The cineol was determined by the resorcinol method in the rectified portion and calculated for the crude oil; the result from two closely-agreeing determinations was 32 per cent. By the rapid phosphoric acid method the amount was 27 per cent. in the crude oil.

The Terpenes. - When the cineol in the oil of the first two fractions was combined with phosphoric acid in excess, the terpenes separated from the thick jelly formed, and could be poured from the cineol phosphate. After agitating with 50 per cent. solution of resorcinol, the separated liquid, after well washing and drying, had specific gravity at 15o = 0.8641; rotation aD + 11.8°; refractive index at 20° = 1.4756.

The oil was tinged yellow, had an odour resembling that of cymene, and was very mobile. The terpenes were redistilled, when 50 per cent. came over between 157-167o (corr.) and 34 per cent. between 167-172o. These two fractions gave the following results :-

The nitrosochloride was readily formed with the first fraction, and this, when purified, melted at 104o C. It was thus evident that the chief terpene in the oil of this species was dextro-rotatory pinene.

The specific gravity and refractive index suggested that the other terpene was limonene or dipentene, and probably cymene was present also. The oil of this species is thus shown to contain a predominance of terpenes, and to have little value for commercial purposes.

The results obtained with the oil of this species were published by us in the Trans. Roy. Soc, South Australia, 1916.