(R.T.B., Proc. Linn. Soc, N.S.W., 1900, p. 305, t. XVI.) Silver-topped Mountain Ash.

Systematic. - A very tall tree, occurring on the top of mountain ranges in the south-east corner of New South Wales, also Victoria, and Tasmania. Bark stringy, reddish, extending well up the trunk. Abnormal leaves large, broadly lanceolate, oblique; venation prominent, spreading, intramarginal vein removed from the edge. Normal leaves comparatively large, often 9 inches long and 2 inches broad, lanceolate, acuminate; venation prominent, lateral veins spreading, intramarginal vein removed from the edge. Peduncles axillary, about 6 lines long, slightly compressed, bearing from six to ten flowers. Buds clavate, 6 to 7 lines long; calyx tube short, merging into a pedicel 3 to 4 lines long; operculum hemispherical, obtuse.

Fruit. - Pyriform; rim thick, truncate or countersunk; valves small, not exserted; about 4 lines long and 3 lines broad.

The fruits are uncommonly like those of E. Sieberiana and E. obliqua.

Habitat. - Delegate Mountain, lower sides of Snowy Mountains, New South Wales; Victoria; Tasmania.

REMARKS. - It is difficult, from herbarium specimens to differentiate this species from E. Sieberiana, F.v.M., and E. obliqua, L'Her. The leaves are also similar to those of E. Iævopinea, R.T.B., but in the fruits and in its economic products it is quite distinct from that species. The buds are very similar to those of E.Sieberiana, F.v.M.. but the timber, bark, and oil show it not to be that species, and the same may be said of E. obliqua. Maiden (Vict. Nat., vol. XVIII, p. 124) places this species as E. dives, Schau., from which Eucalyptus we find it differs in abnormal leaves, mature leaves, bark, timber, and the presence of an aroma in its leaves which is entirely absent from the true E. dives; he later places it with E. gigantea, Hooker's name for E. obliqua. We have fully discussed the claims of this species to specific rank in our "Eucalypts of Tasmania, and their Essential Oils," Roy. Soc. Tas., 1912, and where we show it is not E. gigantea. It can always be determined in the herbarium by the perfume emanating from the leaves when the box in which the material is contained is opened.

ESSENTIAL OIL. - Material for distillation was collected in July, 1908, at Mt. Wellington, Tasmania, at an altitude of about 2,500 feet above sea-level. The principal constituent in the oil of this species was phellandrene, and both cineol and pinene were almost absent. The peppermint constituent, piperitone, was present in small amount. The results obtained with the oil of this species from Tasmania are in remarkable agreement with those of the oil of this species from Delegate Mountain, southern New South Wales, collected in February, 1899 (results of which were published in the first edition of this work), although the distance separating these localities is great. The difference in the time of the year when the material was collected naturally influences the physical characters somewhat, because the principal terpene common in the oil of Eucalyptus species is usually present in greatest amount during the early summer months.

The yield of oil from leaves and terminal branchlets was 1.88 per cent. The crude oil was of a lemon-yellow colour. It had specific gravity at 150 C. = 0.8664; rotation aD - 48.4°; refractive index at 20° = 1.4846, and was insoluble in 10 volumes 80 per cent. alcohol. The saponification number for the esters and free acid was 3.1.

On rectification, the usual amount of acid water and volatile aldehydes came over below 1720 C. (corr.), at which temperature the oil commenced to distil. Between 172-1830 C, 65 per cent. distilled; between 183-2340, 12 per cent., and between 234-2700, 16 per cent. These fractions gave the following results: -

The low specific gravity of the high-boiling constituents of the oil of this species is worthy of remark, and is quite unusual for a first distillation.

The following tabulated results with the two oils show how closely they agree: -

It is thus seen that the characteristic features of the one oil are also shown with the other, and as the botanical material was quite in agreement it is evident that this species is common to both Tasmania and Eastern Australia.

Material of the "Gum-topped Stringybark " for distillation, was collected at Strickland, Tasmania, in August, 1912. The oil was found to agree in all respects with those recorded above. It contained the same constituents, practi-cally in the same amounts, and the physical characters of the oils agree most closely. The specific gravity at 150 = 0.8596; rotation aD - 47.4°; refractive index at 200 = 1.4812, and was insoluble in 10 volumes 80 per cent, alcohol. The saponification number of esters and free acid was 3.2. The yield of oil was 1.3 per cent., which is somewhat less than is usual with this species; but the time of the year probably accounts for this.

Material of the "Gum-topped Stringybark," growing at Lake Sorell, Tasmania, was sent for distillation in August, 1912. The trees were those originally mentioned by Mr. Stephens as growing at this locality. These trees are undoubtedly Eucalyptus Delegatensis, and the oil agreed with those from the "Gum-topped Stringybark," growing at Strickland, and Mt. Wellington, in Tasmania, and from the New South Wales trees of this species. The same constituents were present and in practically the same proportions, while the physical characters agree most closely. The specific gravity of the crude oil at 150 C. = 0.8676; rotation aD - 477°; refractive index at 20° = 1.4819, and was insoluble in 10 volumes 80 per cent, alcohol. The comparative constancy in the characters of the oil of this Eucalyptus species is thus conclusively shown.

The results obtained with the Tasmanian material were published by us in the Proc. Roy. Soc, Tasmania, October, 1912.

The sample from Delegate Mountain was stored in the dark, and in November, 1919, was again analysed. Very little alteration had taken place during the twenty years the oil had been kept, except that the specific gravity had increased somewhat, and the optical rotation diminished about 27 degrees. This diminution in rotation is not wholly due to the phellandrene, because the loss on the rectified portion was only 10 degrees. It is evident that the alteration of the piperitone is largely responsible for the less rotation. 64 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 3 per cent. of that constituent.

Plate LXXIV.

Eucalyptus Delegatensis, R.T.B. Southern Mountain Ash