The first member of the paraffins (probably belonging to the aliphatic series) occurring in the Eucalypts was isolated from the crude oil of E. acervula, Hook.f., the "Red Gum" of Tasmania. This substance was first described in a paper published by us in the Proc. Roy. Soc, Tasmania, October, 1912. This paraffin is a saturated hydrocarbon, and probably belongs to the CnH2n + 2 group. It resembles in appearance, odour on ignition, chemical behaviour, and general characters, the paraffin derived from mineral oils, generally known as " paraffin wax."

When finally purified, the stearoptene was perfectly white, of a paraffin-like nature, and without odour; on burning, the odour was identical with that of ordinary paraffin when similarly heated and ignited. The melting point was 55 to 560 C, determined by the capillary tube method in water, and in other ways.

Under the microscope it was seen to be crystalline, and when melted and allowed to slowly cool, the crystals polarised in colours. They were not very symmetrical however, but vermiform, often tending to the shape of the letter S. When dissolved in carbon tetrachloride, and bromide added, the colour was not removed; it was thus a saturated substance. Concentrated sulphuric acid had no action upon it in the cold, nor did the usual oxidising mixture of potassium bichromate and sulphuric acid act upon it in the cold, and only slightly on continued boiling. Concentrated nitric acid appeared to have no action in the cold, and it was but slowly attacked on boiling, acting in this respect similarly to the ordinary paraffins. A solution of potassium permanganate in the cold had no action on it after many days.

Although the paraffin was isolated from the oil of E. acervula, from material collected from two different localities in Tasmania, yet the melting point for both samples was identical. The melting point, 55 to 560 C, cannot, however, be taken as that of Eucalyptus paraffins generally, and the corresponding stearoptene isolated from the oil of E. Smithii, melted at 640 C. (See paper Roy. Soc, N.S.W., July, 1913.)

It is thought that these paraffins probably consist of two or more homo-logues, and this is suggested from the results obtained with the oil of E. acervula, which apparently contained a second paraffin, liquid at ordinary temperatures. The higher melting point of the stearoptene from E. Smithii, over that from E. acervula, is perhaps one distinguishing feature between the oils of the different groups.

The aliphatic paraffins cannot be considered as very rare constituents in essential oils, as their presence has been shown in those of more than a dozen different plants. Essential oils containing paraffin in greatest amount are Rose oil and Chamomile oil, and in these the stearoptene is often so abundant that the oil congeals on cooling. The paraffin recorded from Neroli oil melts at exactly the same temperature as that from the oil of E. acervula, while that in Chamomile oil only differs by one degree. No less than eight paraffins have been recorded from other essential oils, the melting points of which are within one degree of that isolated from the oil of E. Smithii.

It is perhaps worthy of remark that the first paraffin isolated from the Eucalypts was from the oil of a species (E. acervula) which contains a considerable amount of geraniol, a constituent also present in Rose oil. On the other hand the oil of E. Macarthuri, which has a very large amount of geraniol, does not appear to contain it. That the paraffin was derived from the leaf oils of E. acervula and E. Smithii is evident from the fact that these species were not in bloom when the oil was distilled.

Methods of Preparation. - Portions of the crude oils of two consignments of E. acervula were dissolved in a large excess of 80 per cent. alcohol, when a copious, flocculent substance separated. The precipitate was filtered off, using a hardened filter, washed with alcohol, and the solid fat-like substance melted on the water bath to separate adhering water and alcohol. The amount of crude material thus obtained from the oil of one sample was equal to 076 per cent., and from the other 0.82 per cent. This method, however, was somewhat wasteful. The crude oil was then distilled, when the portion boiling above 280° C. became semi-solid when cold; this was boiled in alcohol, filtered hot, cooled, and the process repeated. After standing some time the precipitate was filtered off and boiled in acetic ether, which was found to be a good solvent for the purpose, as the paraffin was little soluble in the cold. On cooling, the substance separated, most of the impurities remaining in solution. The semi-crystalline paraffin was then boiled in alcohol, a little animal charcoal added, and filtered hot. It was finally dissolved in chloroform and precipitated by the addition of alcohol. When thus obtained it differed in no respect from the corresponding material precipitated directly from the crude oil by alcohol.

The paraffin was separated from the oil of E. Smithii by steam distilling the oil until the greater portion had come over, and treating the residue with cold 80 per cent. alcohol, when the paraffin was precipitated. It was then purified in a similar manner to that of E. acervula.