Practically all crude Eucalyptus oils contain phenols, more particularly if the original distillations have been at all extended.

The actual amount in the oils of most species is, however, very small, and consequently phenols are not usually found in Eucalyptus oils of commerce, for the reason that these have in most cases been rectified by steam distillation before placing on the market, or else the original distillations have not been continued for a sufficiently long period.

The greatest quantity of crude phenols we have yet obtained from the oil of any species of Eucalyptus was 2 per cent., from that of E. Risdoni. In most species, however, the amount does not exceed 0.5 per cent., whilst in some of them probably less than 1/10 of that small quantity is present.

Two phenols are found in Eucalyptus oils, one of which is now described for the first time. They have been named tasmanol and australol. The former of these is liquid and occurs in greatest amount in the cineol-phellandrene Eucalyptus oils derived from such species as E. linearis, E. Risdoni, etc. Its presence is indicated by the very red colour of these crude oils when they have been distilled from iron vessels. This group of trees is more extensively developed in Tasmania than in Australia, and for that reason the name tasmanol was chosen for the liquid phenol.

Australol is a beautifully crystallised phenol and occurs in greatest amount in the oils of the typical "Boxes," as E. hemiphloia, E. Woollsiana, etc. It is also present in the more pronounced cineol oils, derived from species of the "Gum" group. These two Eucalyptus groups (the "Gums" and the "Boxes ") are extensively developed on the mainland of Australia, whilst the "Boxes" do not occur in Tasmania. The name australol has thus been chosen for the crystallised phenol, as it is principally derived from the oils of the mainland species.

Our experience indicates that both these phenols occur together, one or the other predominating in the oils of species belonging to certain groups. They may thus be somewhat closely related bodies.

It seems highly probable that the yellow colour of certain rectified cineol-beaing Eucalyptus oils is due to the influence of the crystallised phenol, particularly as it is more pronounced in those species yielding yellow-tinted oils, and when gently oxidised becomes of a bright yellow colour. This is particularly noticeable' when the alcoholic solution is treated with ferric chloride.

Eucalyptus oils in which tasmanol is the pronounced phenol are water-white when rectified, this being traceable, perhaps, to the presence of the methoxy group in tasmanol, as australol has not this grouping. Eucalyptus oils containing over 70 per cent. of cineol thus occur in two forms - (a) the water-white oil from E. Australiana, and (b) the yellow-tinted oils from such Eucalypts as E. polybractea, E. globulus, etc.

The announcement of the occurrence of phenols in Eucalyptus oils was made by Professor R. Robinson and one of us, in a paper published by the Royal Society of New South Wales, in January, 1915. The paper deals with tasmanol, but also mentions the occurrence of a second phenolic body. Professor Robinson now resides in England, so that the further investigation of these phenols has devolved upon us.

The phenols were removed from the crude oils in the usual manner by shaking with dilute aqueous sodium hydrate, washing the aqueous solution with ether to remove adhering oil, acidifying and extracting with ether. The residue, which contains small amounts of acetic and butyric acids, was washed with dilute sodium bicarbonate, extracted with ether, the ether removed, and the phenols distilled.

The product from the oil of E. linearis was utilised for the earlier determination of tasmanol, whilst that for the later investigation was obtained from the oil of E. Risdoni.

For the work on australol the oil of E. hemiphloia was utilised.