(A. Cunn., Herb.) Yellow Box.

Systematic. - Generally a fair-sized tree. Bark persistent, smooth, and buff-coloured, or sometimes rugged towards the base; of a rich yellow colour on the inner side. Abnormal leaves oval, or ovate-lanceolate, thin, variable in size; venation faintly marked, lateral veins parallel, distant, intramarginal vein much removed from the edge. Normal leaves lanceolate to ovate-lanceolate, under 6 inches long; venation not well marked except the intramarginal vein, which is removed from the edge, and is so distinct at the base as to give a trinerved appearance to the leaf; dry a pale yellow colour. Peduncles short, axillary, slender, with about six flowers in the umbel. Calyx scarcely 2 lines in diameter, conical, on a pedicel of about 2 lines; operculum short, hemispherical, obtuse.

Fruit.- Mostly hemispherical, but occasionally pyri-form; rim thin, sometimes with a constriction immediately below it; valves not exserted; under 3 lines in diameter.

The fruits, with the strongly-marked rim which sometimes becomss detached, much resemble E. Black-burniana and E. Laseroni, whilst the other form approaches in shape E. odorata or E. paniculata.

Habitat.- -Tableland from Queensland into Victoria.

REMARKS. -The common name "Yellow Box" appears to be uniformly applied to this tree, both in New South Wales and Victoria. It derives its vernacular name from (1) the yellowish appearance of the inner surface of the bark; (2) the timber, which is hard, close, interlocked, and pale yellow coloured, and very durable. It is highly prized as fuel. It is a very distinct species, and no better example could be quoted of specific characters of the Genus than is illustrated in this widely-distributed Eucalyptus, for its botanical characters show little variation, whatever the environment may be.

ESSENTIAL OIL. - Leaves and terminal branchlets for distillation were obtained from Rylstone, N.S.W., in April, 1898. The yield of oil was 0.87 per cent. The crude oil was red in colour, and had an odour resembling the cineol-pinene oils generally. The presence of volatile aldehydes was also shown. The oil was rich in cineol, and when rectified was almost colourless, and, as a cineol-pinene oil, of very fair quality, although the specific gravity was remarkably low, and in this did not reach the standard for specific gravity (0.91) as laid down by the British Pharmacopoeia. This low specific gravity of the oil from this species is perhaps partly due to the time of the ye?r when distilled, and also to the presence of a small quantity of phellandrcne present in the oil. This species is probably one of the links that connect the phellandrene-bearing oils with those belonging to the more pronounced cineol-pinene groups. That this tendency is in the direction of the phellandrene group of Eucalyptus oils, is indicated by the removal of the marginal vein far from the edge of the leaves, a character which shows affinity with those species giving phellandrene-bearing oils. The variation in specific gravity of Eucalyptus oils is largely governed by the amount of high-boiling constituents present, and for this reason the specific gravity of the oil of any one species varies slightly at different times of the year. Pinene was present in the oil of this species, and from the results, as well as on theoretical grounds, it would appear that the oil consisted very largely of cineol and pinene, with a small quantity of phellandrene.

The crude oil had specific gravity at 150 C. = 0.9046; rotation aD + 6.50; refractive index at 20° = 1.4649, and was soluble in 6 volumes 70 per cent, alcohol. The saponification number for the esters and free acid was 7.2.

On rectification 2 per cent. distilled below 1620 C. (corr.). Between 162-1830, 83 per cent, distilled; between 183-2550, 8 per cent, came over, and between 255-2700, 4 per cent, distilled. These fractions gave the following results: -

The cineol, determined by the phosphoric acid method in the large fraction, was 60 per cent. (O.M.), indicating about 52 per cent in the original oil.

The above results being unusual for an oil so rich in cineol, a second distillation was made, but in this instance the rectification was carried to 1900 C. The large fraction represented 88 per cent. of the original oil. It had a specific gravity of 0.9019 at 150 C, and optical rotation aD + 7.1°. The cineol determined by the phosphoric acid method was 59 per cent. (O.M.), a mean of closely agreeing results.

Material of this species was also obtained from Condobolin, N.S.W., in March, 1901. It had specific gravity = 0.9042, contained similar constituents to the above, and was soluble in 6 volumes 70 per cent. alcohol.

Material of this species for distillation was also obtained from Barber's Creek, N.S.W., in June, 1898. This is the cold time of the year in Australia, and consequently the oil contained less pinene and had a higher specific gravity. The yield of oil was also less. The ester content was somewhat high in this sample, and phellandrene could not be detected, indicating a diminution of that constituent at this time of the year. The specific gravity of the crude oil was 0.9321; and optical rotation aD + 5.0°. The fraction (81 per cent, distilling below 1830 C.) had specific gravity = 0.9143; and optical rotation aD + 6.6°. The saponification number for the esters and free acid was 21.96. The cineol, determined by the phosphoric acid method in the rectified oil, was 60 per cent. (O.M.). The crude oil formed a clear solution with 1 1/2 volumes 70 per cent, alcohol.