(R.T.B., Proc. Linn. Soc., N.S.W., 1899, p. 294, t. XXI.) Slaty Gum.

Systematic. - A tall tree, with a smooth bark. The foliage, branchlets, buds, and fruits, glaucous. Abnormal leaves broadly lanceolate, 6 inches long, and over 3 inches wide, on a petiole over 1 inch long, very obtuse, glaucous on both sides; venation distinct. Normal leaves mostly short, oblong-lanceolate, very obtuse, rarely acuminate, occasionally reddish in colour; venation fairly distinct, lateral veins not quite so marked, intramarginal vein close to the edge. Peduncles axillary, but mostly in large terminal corymbs, exceeding the leaves. Buds on young trees, 3 lines long, 1 1/2 lines in diameter, sessile or on short pedicels; operculum hemispherical, obtuse; on mature trees, 4 to 5 lines long, 1 line in diameter; calyx tube tapering into a filiform pedicel; operculum conical, acute.

Fruit. - Small, on a slender or almost filiform pedicel, turbinate; rim thin, capsule sunk; valves not exserted; mostly 1 line in diameter and under 2 lines long.

In shape they are not unlike E. crebra, but are always glaucous.

Habitat. - Murrumbo, Goulburn River, and northward, Jerry's Plains and Singleton, and Mountains west of Went-worth, New South Wales.

REMARKS. - This is a well-marked species, and in the field could never be confounded with any other Eucalyptus. The fruits resemble those of the narrow-leaved "Ironbark," E. crebra, and the leaves of those of E. ovalifolia, the Rylstone " Red Box," but it differs from them in every other specific character. The late Dr. Woolls was very emphatic that this tree should be regarded as quite distinct from E. polyanthemos, with which species it had previously been confused. E. polyanthemos has a "Box" bark and other characters which are sufficient to differentiate it from E. Dawsoni. It is also distinct from E. ovalifolia.

ESSENTIAL OIL. - Leaves and terminal branchlets for distillation were obtained from Bylong, N.S.W., in October, 1898. The yield of oil was 0.18 per cent. The crude oil was of an orange-brown colour, and notably of a viscous nature. This viscosity was due to the presence of an extra amount of the sesquiterpene and higher-boiling bodies. The oil oxidised somewhat readily on exposure, drying much in the same way as does boiled linseed oil. The first fraction consisted largely,of phellandrene, but only a very small quantity of cineol could be detected. Esters were not very pronounced, so that the oil was largely a terpene one, although a considerable amount of liquid eudesmol was present.

The crude oil had specific gravity at 15° C. = 0.9418; refractive index at 200 = 1.5077, and was soluble in 2 volumes 80 per cent. alcohol. The light did not pass well. The saponification number for the esters and free acid was 13.3.

On rectification, 1 per cent, distilled below 1720 C. (corr.). Between 172-2040, 32 per cent, distilled; between 204-2550, only a few drops came over, and between 255-2750, 38 per cent, distilled. These fractions gave the following results: -

This sample of oil had been stored in the dark, and in September, 1919, twenty-one years after, was again analysed. The lrotation of the lower boiling portion had diminished considerably, and the specific gravity had increased a little, otherwise not much alteration had taken place during this long period. 20 per cent, distilled below 190° C. The crude oil and the rectified portion gave the following results: -

The cineol was determined by the resorcinol method in the rectified portion; when calculated for the crude oil, the result was 5 per cent.