The various types of Eucalyptus oils find employment in many ways, and new uses for them are frequently being discovered. The industry to-day has reached very fair dimensions in Australia, and the outlook for the future utilisation of these oils in new branches of manufacture is most promising.

It is not generally known, however, that among the first natural raw products exported from Australia was Eucalyptus oil. In the "Journal of a Voyage to New South Wales," by John White, Esq., Surgeon-General to the Settlement, and published in London, 1790, is this statement in the appendix, p. 227: - " The name of 'Peppermint Tree' has been given to this plant by Mr. White on account of the very great resemblance between the essential oil drawn from its leaves and that obtained from the 'Peppermint' (Mentha piperita) which grows in England. This oil was found by Mr. White to be much more efficacious in removing all cholicky complaints than that of the English 'Peppermint,' which he attributes to its being less pungent and more aromatic. A quart of the oil has been sent by him to Mr. Wilson."

The above, written by Dr. J. E. Smith (founder of the Linnean Society) shows, we think, that the credit for being the first to produce and use Eucalyptus oil therapeutically was Surgeon-General White, and to him thus belongs the honour of founding the Eucalyptus oil industry.

Mr. Maiden, however, gives the credit to Surgeon Considen, when naming a species after that gentleman, Proc. Linn. Soc, N.S.W., Vol. 29, 1904, p. 477.

In Considen's letter to Sir Joseph Banks, dated Port Jackson, 18th November, 1788, and published in the Historical Records of New South Wales, Vol. 1, part II, p. 220, is found the following paragraph in this connection: -

"This country produces a variety of flowers and shrubs totally unknown in Europe, and five or six species of wild myrtle, some of which I have sent to you dried. An infusion of the leaves of one sort is a mild and safe astringent in the treatment of dysentery. We have a large peppermint tree, which is equal, if not superior, to our English peppermint. I have sent you a specimen of it. If there is any merit in applying these and many other simples to the benefit of the poor wretches here, I certainly claim it, being the first who discovered and recommended them."

It seems to us that Considen worked on the native plants mentioned in other directions, at any rate, he makes no claim whatever for the oil, nor is the word oil mentioned in his letter. Unless further evidence is produced, it is difficult to see how Considen can be acclaimed as the founder of the Eucalyptus oil industry.

Among Sir Joseph Banks' papers, dated 17th November, 1789, reference is also made to a bottle of Eucalyptus oil which had been forwarded to him by Governor Phillip in the ship "Golden Grove," together with other exhibits, but there appears to be no evidence that Considen was interested in this. (See footnote, Records N.S.W., Vol. I, part 11, p. 283.)

(a) For Pharmaceutical Purposes. - The species from which the first sample of Eucalyptus oil had been distilled was E. piperita, and this Eucalypt gives a product consisting of phellandrene, piperitone, cineol and some minor constituents.

It is worthy of mention that the Eucalyptus oil industry was established in Australia on oils of this class. It was in 1853 that Baron von Mueller recommended the. distillation of Eucalyptus oil, and he claims this in his "Extra Tropical Plants," under E. amygdalina. In 1854 Mr. J. Bosisto established, in Victoria, the first factory for the commercial distillation of Eucalyptus oil in Australia, the species utilised being chiefly the one known at that time as E. amygdalina. The oil of that species contained phellandrene, piperitone and cineol, and in constitution had some resemblance to that of E. piperita.

As the more pronounced cineol bearing Eucalyptus oils became in request, those containing phellardrene receded in favour, and to meet this demand the "Mallee" oils came into prominence, while in Tasmania the chief species employed was E. globulus. The "Mallee" oils, being as a rule more closely related to the "Boxes," have, in most cases, distinctive properties from those of the E. globulus type, in that they contain the aldehyde aromadendral, a constituent which has been shown by Dr. Cuthbert Hall and others to have five or six times the bactericidal value of cineol.

The demand at present for medicinal oils is mostly for those having a high cineol content, and the United States Pharmacopoeia demands a minimum of 70 per cent. of that constituent; but, as can be seen from the results recorded in this work, only a comparatively few species yield oils of this character in sufficient amount to be profitable for distilling at the usual price paid for cineol oils, and for that reason the demand for those containing 70 to 80 per cent. of cineol has, for some time past, far exceeded the supply.*

The British Pharmacopceia's standard is more reasonable, only requiring 55 per cent. of cineol. For the supply of oils of this quality Australia has numerous species, as can be seen by referring to the lists under Group III, class (b), and group IV, class (a).

The question, however, is not yet settled as to whether cineol is the most valuable medicinal constituent in Eucalyptus oils, and Dr. Attfield directs attention to this uncertainty in his work on Chemistry (p. 505). Mr. E. M. Holmes (Pharm. Journ. III, 25, p. 501) says that " the chemistry is far in advance of the therapeutic and physiological knowledge of Eucalyptus oils."

In connection with this question an investigation on the bactericidal value of the several constituents of Eucalyptus oils was undertaken by Dr. Cuthbert Hall, of Parramatta, in 1904; these results were published privately.

Considerations respecting the therapeutic value of Eucalyptus oils are beyond the scope of this work, but much information may be found scattered throughout the various scientific and pharmaceutical publications.

Such a large number of constituents occur in oils of the various Eucalypts, that it may be the medicinal value of Eucalyptus oil is more largely due to the admixture of certain of these, than to that of any one individual constituent.

(b) For Mineral Separation.- A? with cineol, other constituents which contain oxygen, such as citronellal, piperitone, aromadendral, geranyl-acetate, etc, as well as the several terpenes, reach a maximum in the oils of particular species of their class, and by taking advantage of this peculiarity, and exploiting those species which contain the desired constituent in greatest abundance, these products are now, or may eventually become, articles of commerce.

* Comraerciallv pure cineol is now manufactured in Australia, and can be supplied in any reasonable quantity if it is desired to use the pure product in preference to the oils.

One very important use to which the phellandrene-piperitone Eucalyptus oils are put is in the separation of metallic sulphides from the gangue, by a flotation process. The use of Eucalyptus oil for this purpose was discovered by Mr. Henry Lavers at Broken Hill, New South Wales, and this is shown in the following claim, made by Mr. J. Ballat, the Chairman of Directors, at a meeting of Minerals Separation Ltd., held in London in December, 1910.

"In Australia a member of our staff there (Mr. Henry Lavers) discovered that certain of the Eucalyptus oils are eminently suitable for the purpose. Less than a pound of this reagent is all that is required to recover the values from a ton of ore. This reagent and process have been properly protected under patents the world over. These processes are ours, and I trust they will be profitable to us ... . and to Australia in particular, by turning part of her vast forests of Euca!yptus to profitable account." The oils from specific species for these experiments were supplied by this Museum.

Since that time very large quantities of oil have been distilled from the "Peppermint" species, both in New South Wales and Victoria, and used for flotation work. E. dives, a "Broad-leaved Peppermint," is generally recognised as yielding the best oil for this purpose, and consequently the product of this Eucalypt is in much request.

This species, together with the "Narrow leaf Peppermint" E. fihellandra, has an extensive range in the States above mentioned, and is particularly abundant at certain localities in the mountain ranges at an altitude of about 1,500 to 3,000 feet. As this particular oil is such a useful article of commerce, and contains piperitone in quantity, it should be good policy to conserve the species (E. dives) for oil production, in those localities where it grows most luxuriantly, more particularly as the "Peppermint" Eucalypts are generally found on poor soil and in mountainous country, not likely to be in much demand for agricultural purposes.

Through the kindness of Mr. A. J. Bedwell, we are able to give the following results as to the flotation efficiency of the oils of E. dives and of E. phellandra, the " Narrow leaf Peppermint." Ordinary material of E. dives was distilled by Mr. W. St. Clair, near Colombo, New South Wales, a square tank with direct firing being used, and the oil collected each hour for eight hours. After we had determined the constants, the oils were forwarded to Mr. Henry Lavers, who ascertained their values for flotation work. The results he obtained are given in column five.