The figures quoted are those published by one of us in the Journal of the Society of Chemical Industry, August, 1918, in a paper prepared to illustrate the value of the Refractometer for determinative purposes, but they may be equally well applied in the present connection.

(1) Eucalyptus Polybractea (a species distilled in both New South Wales and Victoria).

It will be seen that only two oils listed were laevo-rotatory. This is due to the influence of a small quantity of the optically active aromatic aldehyde aromadendral, and indicates that the distillation of the leaves had been extended beyond the usual time. This laevo.rotation is not due to the presence of phellandrene, as that terpene does not occur in any of the oils of this group.

The oil of E. polybractca is one of the richest in cineol, and in the particular cases listed above, that constituent was always in the neighbourhood of 80 per cent.

The solubility was always high; only from i.i to 1.2 volumes 70 per cent. alcohol being required to form a clear solution.

(2) Eucalyptus Austral1ana, "First hour oil." " NARROW LEAF " OR " BLACK PEPPERMINT." (A species distilled in New South Wales.)

In the first edition of this work (page 170, under E. amygdalina) it was shown that by fractional separation during the primary distillation, the oil which came over during the first hour contained the greater portion of the cineol. It is only within the last six or seven years, however, that this mode of procedure has been adopted in commercial distillation, but during that time considerable quantities of a high-class water-white cineol oil have been distilled from E. Australiana in this way. The product so separated is known commercially as "First hour oil," and' is sold for pharmaceutical purposes, the portion distilling later, which contains terpineol and geraniol, being employed in other branches of industry.

Although this "First hour oil" is thus collected empirically, yet it is remarkable how closely the results agree; the oil has a pleasant odour, contains about 70 per cent. of cineol, and will no doubt be in great demand when it becomes better known. Its solubility in alcohol is quite equal to that of the oil of E. polybractea.

(3) Eucalyptus Dives. A "Broad-Leaf Peppermint."

(A species distilled in both New South Wales and Victoria.)

This oil may be considered as the type of the extreme phellandrene Eucalyptus oils, and although inclined to alter its physical characters by age to a greater extent than those of the cineol-pinene class, yet, when freshly distilled, a relative constancy is noticeable, similarly with the oils of the other species of Eucalyptus. The exceedingly high optical rotation is chiefly due to the phellandrene, although the piperitone it contains is also lævo-rotatory; scarcely more than 5 per cent. of cineol is present at any time.

Much of the oil of this species has been forwarded to Europe as the product of E. amygdalina. Although regrettable, yet this misnaming was, to a certain extent, excusable, because E. dives was classified for a long time as a variety of E. amygdalina, and varietal names soon appear to lose their identity.

The oil of E. dives is considered the best of all essential oils for mineral' separation by a flotation process, and considerable quantities have been used in Australia for the separation of metallic sulphides. When it was decided to use Eucalyptus oil for this purpose at Broken Hill, the first contract was for the supply of the oil of this species.

The tendency is now among some distillers in New South Wales to treat the leaves of E. dives for several hours. This extended distillation naturally results in the oil having a higher specific gravity, a less rotation, and to contain a greater proportion of Piperitone than the product of, say, a three 01 four hours' distillation; this is shown in the table above, but for flotation work both are of equal value. For Piperitone production extended distillation gives better returns.

Results illustrating this constancy in chemical characters with other species have been tabulated, and will be found distributed throughout this work; but after all this is only what might be expected, considering the extent of the genus; and from our work on the Tasmanian species it was shown that a large proportion of those Eucalypts growing on the island were identical with trees of the same species on the mainland. It is evident, therefore, that both the botanical and chemical characters must have been stabilised long before Tasmania was separated from Australia, and it is not difficult to accept similar conclusions for practically the whole of the species in the genus.