(H.D. & J.H.M., Proc. Linn. Soc., N.S.W., 1899, P. 614. pl. XLIX.)

Black Gum.

Systematic. - Usually small, gnarled trees, with a trunk of 12 to 18 inches or even 2 feet in diameter. Abnormal leaves quite glabrous, oval to nearly oblong, strictly opposite, up to 1 inch long, the margins undulate, mucronate, with a short point. Normal leaves lanceolate, undulate, equally green on both sides, scarcely shining, on the average probably 4 1/2 inches long and 1 inch broad; intramarginal vein considerably removed from the edge, other veins few, but conspicuous, very oblique. Buds usually four to six in the umbel; operculum and calyx tube about equal, and both tapering towards a. point, the operculum being nearly conical.

Fruit. - Hemispherical in shape, small and sometimes, owing to the shortening of the pedicels, so clustered together as to form a dense head, hence the specific name; with a well defined sharp-domed rim; three or four"-well exserted valves; not exceeding 3/16 of an inch in diameter.

Habitat. - Alluvial flats, following watercourses or depressions. Usually found in damp situations. Braidwood and Rydal, New South Wales.

REMARKS. - In the Proc. Roy. Soc, Tasmania, 1914, p. 30, J H. Maiden claims that this is identical with E. Rodwayi, a determination quite at variance with data we have obtained from each.

ESSENTIAL OIL. - Leaves and terminal branchlets for distillation were obtained from Fagan's Creek, Little River, Braidwood, N.S.W., in October, 1898. The yield of oil was small, 394 lb. of leaves and branchlets giving only 2 1/2 oz. of oil, equal to 0.04 per cent. The crude oil was light orange-brown in colour, was very mobile, and had a somewhat rank odour, with but little resemblance to ordinary Eucalyptus oil. It contained a somewhat large amount of pinene, which was dextro-rotatory; this terpene was proved by the formation of the nitrosochloride, and other tests. Cineol and phellandrene both appeared to be absent. The principal constituent was an ester, the alcohol of which was amyl-alcohol, combined with a solid acid, which has been named eudesmic acid.

The crude oil had specific gravity at 15° C. = 0.956; refractive index at 20° = 1.5005; and was insoluble in 10 volumes 80 per cent. alcohol. The saponification number for the esters and free acid was 112.2.

On rectification, 1 per cent, distilled below 1560 C. (corr.). Between 156-164°, 26 per cent, distilled; between 164-245°, 12 per cent. came over, and between 245-292°, 22 per cent. distilled. The remainder when removed from the still became crystalline on cooling. The fractions gave the following results; - .

Plate LXXIX.

W. Marshall del

Eucalyptus Aggregata, H.D. a J.H.M

Material of this species for distillation was obtained at Rydal, N.S.W., in September, 1909. The yield of oil was 0.038 per cent. The oil was in general agreement with that from Fagan's Creek, and contained a considerable amount of ester, the alcohol of which was amyl, but the solid acid did not agree with the characters obtained with eudesmic acid, ft is thus possible that two esters occur in the oil of this species. Efforts were made to decide this point, and material for distillation was collected at Rydal in January, 1920, but unfortunately, at this time of the year, sufficient oil was not present to separate from the distilled water.

The Rydal oil had specific gravity at 150 C. = 0.9474; rotation aD + 11.2°, and refractive index at 200 = 1.4977. The saponification number for the esters and free acid was 119.5.

The alcohol of the ester was separated, oxidised to valeric acid, and the silver salt of this prepared; the metallic silver thus obtained was 51.74 per cent., which is almost a theoretical result. It was thus evident that the alcohol of the ester was amyl.

The solid acid when purified was in paraffin-like leaflets and melted at 76.5° C.; by titration with a deci-normal solution of sodium hydrate, a molecular value 135.6 was obtained. It was a saturated acid, and when treated with manganese dioxide and sulphuric acid gave an odour of benyaldehyde. This evidence points to this acid being phenyl-acetic acid. Unfortunately the species produces almost the least oil of any, so that sufficient for investigation was difficult to procure.