(Sm., in Trans. Linn. Soc, iii, 284; B.F1., iii, 208.) Blackbutt.

Systematic. - One of the tallest trees of the Genus. Leaves thick, shining, sometimes over 6 inches long, lanceolate, falcate, oblique, drying a very pale colour; venation indistinct, lateral veins parallel, intramarginal vein removed from the edge. Flowers on axillary, flattened peduncles of about 6 lines long, mostly six in the umbel. Calyx tube slightly over 2 lines in diameter, pear-shaped, on a pedicel of from 2 to 3 lines long; operculum about 3 lines long, hemispherical or acuminate.

Fruit. - Pedicellate, semi-globose, truncate; rim sometimes contracted, thin, countersunk or broad and even domed; valves not ex-serted; about 5 lines in diameter.

These fruits are very close in form to E. dextropinea, but the rim in the latter case is generally broader and. the former mostly countersunk.

Habitat. - Coast district and Tableland, New South Wales; Victoria; Queensland.

REMARKS. - "Blackbutt" is a tree well known to timber getters and the trade, and offers no difficulties of determination either in the field or the herbarium, for in the latter it can be named from the leaves alone. The bark varies a little, sometimes being dark-coloured, compact-stringy, and at other times light reddish coloured and loosely stringy.

ESSENTIAL OIL. - Leaves and terminal branchlets for distillation were obtained from the following New South Wales localities: - Canterbury, in June, 1897; Canterbury, in August, 1898; Belmore, in November, 1898; and Currawang Creek, in November, 1898. The yields of oil from these localities varied between 0.08 and 0.18 per cent. The crude oils were of a light-amber colour, with a rank odour, difficult to define. Phellandrene was present, but cineol detected only in very small quantity (5 to 10 per cent.). Pinene was only present in small amount. The higher-boiling portion consisted largely of the sesquiterpene, and it also contained a quantity of the liquid form of eudesmol; this was shown by the increased dextro-rotation. After the oil was acetylated, it had a high saponification number, indicating the presence of free alcoholic bodies, and the saponified oil was also somewhat aromatic. This high-boiling alcohol is characteristic of the oils of several Eucalyptus species, and its presence is shown by the high rotation figures of the higher-boiling fractions. The crystallised form of eudesmol was not detected, under ordinary circumstances, in the oils of this species. The lævo-rotation of the first fraction, caused by the presence of the phellandrene, distinguishes this species from E. dextropinea. The varying amounts of phellandrene and pinene, the one lævo- and the other dextro-, cause the rotation of the oils distilled at different times of the year to be not constant, the lævo-rotation of the phellandrene, when this terpene is pronounced, overcoming the dextro-rotation of the pinene, and the phellandrene, having such a high optical rotation, becomes more active in this way than does the pinene. The eudesmol also influences the rotation to the right.

The following results were obtained with the August sample. The specific gravity of the crude oil at 150 C. = 0.8935; rotation aD + 5.8°; refractive index at 200 = 1.4904, and was not soluble in 10 volumes 80 per cent. alcohol. The saponification number for the esters and free acid was 5.9.

On rectification, 2 per cent distilled below 1720 C. (corr.). Between 172-1830,. 50 per cent, distilled; between 183-2040, 16 per cent, came over, and between 204-2800, 25 per cent, distilled. These fractions gave the following results: -

The third fraction was acetylated, when the saponification number had risen to 56.4, showing the presence of about 23 per cent, of the liquid form of eudesmol in this fraction.

Belmore and Currawang Creek are far apart, but the results obtained with the oils from those localities differed but little from the above, with the exception that the phellandrene was more pronounced in the Belmore sample, and the alcohols in that from Currawang Creek.

The general results obtained with the four samples of oil are here tabulated.

The varying effects on the rotations of Eucalyptus oils by the optically active constituents with opposite rotations is well demonstrated with those from this species, and this peculiarity is very apparent with oils having phellandrene as a pronounced constituent, when pinene is also present in quantity.

The above oils were mixed together and stored in the dark, and in August, 1919, twenty-one years afterwards, the oil was again analysed. Not much alteration had taken place during all that time, as the figures below will show, and the reaction for phellandrene was just as pronounced as formerly. 66 per cent, distilled below 1900 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 11 per cent.