In a paper on Eucalyptus Australiana and its essential oil, read by us before the Royal Society of New South Wales, December, 1915, it was shown that a considerable quantity of a high-boiling aromatic alcohol was present in the oil of this species, and that it was concentrated to a considerable extent in that portion of the oil which came over during the second and third hours of distillation, and analysis showed that between 30 and 40 per cent. of the third hour oil consisted of this alcohol. Considerable work has now been undertaken with this alcohol, and it has been isolated from the oils of several species, with the result that it is now shown to be terpineol, and to exist in Eucalyptus oils in both the dextro- and lævo-rotatory modifications.

Voiry had shown in 1888 that terpineol and its esters occurred in the oil of E. globulus (Compt. Rend. 106, 1888, 1419).

Dextro-rotatory terpineol has now been isolated from the oils of some of the earlier members of the genus, viz., E. diversicolor and E. carnea; and the lævo-rotatory terpineol from the oils of E. Australiana and E. phellandra. The terpineol isolated from the oil of the latter species had a higher lævo-rotation than had that of the former. It may be supposed, therefore, that terpineol - similarly with geraniol - runs through the whole genus, occurring in larger or smaller amounts in the oils of the several species, sometimes in the free condition, and as terpinyl-acetate or terpinyl-butyrate.

The alcohol has so far been found to occur in the liquid form, but was crystallised when subjected to considerable cold for a sufficiently long period. The solid form when purified melted at near 35° C , and had the characteristic lilac odour of terpineol.

In the first edition of this work the oil of E. phellandra (known at that time as a form of E. amygdalina), although containing only about 30-40 per cent. of cineol, was shown to be exceedingly soluble in 70 per cent, alcohol. This peculiarity for an oil in which phellandrene occurs in some quantity is now known to be chiefly due to the presence of the terpineol. The species E. Australiana was not discovered until many years later.

When the crude oil of either E. Australiana or E. phellandra was treated with phosphoric acid on a watch glass and the cake of cineol phosphate allowed to remain in the open for two or three days, crystals eventually appeared in the.

otherwise liquefied mass. These crystals were shown to be terpin hydrate, and had evidently been formed by the action of the phosphoric acid on the terpineol.

When the crude oil of E. Australians was determined quantitatively for cineol, and the cake of cineol-phosphate decomposed in the ordinary way, crystals often occurred in the separated cineol. They were sometimes present in such quantity as to render the junction of the liquids indistinct and correct reading difficult. These crystals were also found to be terpin hydrate, and had evidently been formed by the action of the phosphoric acid on the terpinol. Not being soluble in the petroleum ether, the crystals remained with the cineol phosphate.

H. J. Prins (Chem. Weekblad, 1917, 14, pp. 630-631) has shown that a good yield of terpin hydrate can be obtained by agitating terpineol with 80 per cent, phosphoric acid at 30° C.

This reaction with the oils of E. Australiana and E. phellandra is apparently one distinguishing feature between them and other Eucalyptus oils on the market, while the presence of the phellandrene distinguishes the oil of the latter species from that of the former.

(a) Terpineol From The Oil Of E. Australiana

This was isolated from the "second hour" oil of E. Australiana, distilled for us by Mr. Gough, of Youri, New South Wales, in November, 1919. The crude oil had the following characters: - Specific gravity at 15° C. = 0.90815 rotation aD - 2.0° C.; refractive index at 200 = 1.4704, and was soluble in 1 1/2 volumes 70 per cent. alcohol. The saponification number for the esters, by heating 1 1/2 hours, was 5.2; after acetylation it was 76.9 by heating, and 24.5 in the cold with two hours' contact. The cineol was determined by both the resorcinol and the rapid phosphoric acid methods in the portion boiling below 1900; when calculated for the original oil the result was 42 per cent. by resorcinol, and 25 per cent. by phosphoric acid.

4,000 c.c. of the oil were then distilled, when 65 per cent, came over below 1900 C. This fraction and the portion boiling above 1900 gave the following results: -

By repeated fractionation of the portion boiling above 1900 C. at 10 millimetres pressure, the following fractions were finally obtained (temperatures uncorrected): -

The lower boiling fraction and the residue were discarded. The second fraction, 100-1010 C. at 10 millimetres, gave the following results: -

Both the nitrosochloride and the urethane were readily formed and in good quantity. These results indicate that the alcohol was terpineol and that the lævo.rotatory modification predominated to a small extent in the oil of this species.

The portion boiling between 101-1100 C. was again fractionated at 10 millimetres, when 30 c.c. were obtained boiling between 108-1100 C. This fraction had a distinct odour of geraniol. The specific gravity at 150 = 0.9316; rotation aD - 1.5°; refractive index at 200 = 1.4841, and yielded a good amount of a urethane, melting at 1120. It is thus evident that a considerable amount of terpineol was also present in this portion. That it also contained geraniol was shown by the formation of citral on oxidation.

That geraniol is a common constituent in the oil of E. Australiana is also suggested from the frequent presence of citral in the natural oil, and we have isolated this aldehyde in a pure condition from the oil of this species distilled from material growing in the Burraga district of New South Wales.