(Hooker, Ic. PL, t., 619.) Spotted Gum.

Systematic. - A tall tree, with a long clean trunk. Bark smooth, somewhat shining, whitish or sometimes reddish-grey, mottled by bluish-white or brown-reddish spots, indicating the places or rudiments of patches of older bark, hence the vernacular name. Abnormal leaves sometimes 1 foot long and 3 inches broad, thick, pale on the under side, venation similar to that of the normal leaves, which are long, lanceolate, slightly falcate, from 4 to 6 inches long; venation distinct, fine, oblique, parallel; intramarginal vein close to the edge, somewhat obscured. Flowers in axillary or terminal panicles, on pedicels 2 to 3 lines long. Calyx oblong or cylindrical, 3 to 4 lines in diameter; outer operculum hemispherical but depressed, either with or without a small point.

Fruit. - Urn-shaped; rim thin, sunk; valves inserted ; about 1/2 inch long.

It is almost similar in shape to that of E. citriodora, and uncommonly resembles the smaller fruited form of the " Bloodwood " species.

Habitat. - Coastal Districts, and Tableland from Clyde- River, N.S.W., into Queensland.

REMARKS.- One of the best known trees, in the coast district of these States. The common term " Spotted Gum " is a little confusing, as several other species with a smooth bark are known by that name. The Queensland tree E. citriodora was at one time placed as a variety of E. maculata, but the analogy is only in the shape of the fruits. The two otherwise are quite distinct. The chief economic of E. maculata is its timber, which is largely used locally for coachbuilding. It is a splendid bending wood.

ESSENTIAL OIL. - Leaves and terminal branchlets for distillation were obtained from Currawang Creek, N.S.W., in July, 1898. The yield of oil was 0.23 per cent. The crude oil was of a light orange-brown colour, and had a turpentine-like odour, with an aromatic secondary one. A somewhat large amount of pinene was present, but phellandrene was absent. Cineol occurs in fair' amount. The third fraction consisted largely of the sesquiterpene. The predominance of the terpenes accounts for the comparative insolubility of the oil in alcohol, it requiring 1 volume of 80 per cent. alcohol to form a clear solution. The aldehyde citronellal does not appear to occur in the oil of this species even in traces, so that in cases where this aldehyde has been recorded for the oil of E. maculata, that of E. citriodora had been worked upon.

The crude oil had specific gravity at 15° C. = 0.9201; rotation aD, + 7.7°; refractive index at 20o = 1.4804. The saponification number for the esters and free acid was 9.5.

On rectification, 2 per cent. distilled below 166o C. (corr.). Between 166-183o, 43 per cent. distilled; between 183-260o, 22 per cent. came over, and between 260-2800, 27 per cent. distilled. The last fraction consisted very largely of the sesquiterpene. The fractions gave the following results :-

the cineol was determined by the phosphoric acid method in the first fraction. The result was 39 per cent., which represents about 18 per cent. in the crude oil (O.MA____________

To test the constancy of the oil products of this species material was obtained from Woodburn, in the north-east corner of New South Wales, the previous consignment having come from the south-eastern portion of that State. The oil was distilled in September, 1901, so that more than three years separate the two distillations. There was a close agreement between the two samples of oil, the physical and chemical characters being in accord. The higher specific gravity of the Currawang Creek sample was due to a larger amount of the sesquiterpene. Pinene was present in quantity, but phellandrene was absent. The cineol determined by the phosphoric acid method gave 20 per cent. (O.M.). The specific gravity of the crude oil at 15° C. = 0.8959 ; optical rotation aD + 5.1°. The saponification number of the esters was 6.5. The crude oil required 4 volumes 80 per cent. alcohol to form a clear solution.

The sample from Woodburn had been stored in the dark, and in August, 1919, was again analysed. But little change had taken place in the crude oil during the eighteen years it had been kept. The crude oil and the fraction gave the following results. 60 per cent, distilled below 190° C: -

The cineol was determined by the resorcinol method in the fraction, and calculated for the crude oil; the result was 25 per cent. By the rapid phosphoric acid method it was 21 per cent. when calculated for the crude oil.