The time of year also appears to have some influence on the ester formation in the oil of E. Macarthuri, but to a less extent than the age of the leaf material, so that the oil distilled commercially from cultivated plants of this species should show a high ester content, perhaps, as an average, not less than 5 per cent. in excess of that found in the leaf oil collected from old trees growing naturally,

Free acetic acid always occurs in the oils of this species, and phenols are also present, so that the crude oil is usually red in colour, particularly if the digester and worm of the still had been constructed of iron.

Determination of the Ester. - The ester was determined by heating on the water bath, under reflex condenser, with 20 c.c. semi-normal alcoholic potash, and titrating with semi-normal sulphuric acid in the usual way. The following figures give the results obtained with an oil containing the least amount of ester we have so far experienced with the oil of this species: -

As the ester was wholly geranyl-ace-tate, with a molecular weight 196, the percentage of ester was 60.34.

To determine the free acid a portion of the oil was agitated with dilute aqueous sodium hydrate, washed and dried.

1.945 gram, neutral oil required 0.3332 gram. KOH ... S.N. = 171.3.

The result from this is 59.95 per cent. of ester, and free acid showing a saponification number 1.1, or an ester value of 0.39 per cent. It is not permissible to attempt the determination of the free acid by alcoholic potash in the usual way, as the saponification of the ester commences at once, and with two hours' contact the whole is saponified. This is shown by the following result obtained with the neutral oil as above.

In this case only one and a half hours elapsed after the addition of the alcoholic potash before titration.

1.65 gram, required 0.2828 gram, potash ... S.N. = 171.4.

This result is equal to 59.99 per cent., and shows that the ester was entirely saponified during that time.

The Free Alcohol. - The acetylation of the free alcohol in the above sample was carried out in the usual manner, by boiling for one hour and a half with acetic anhydride and anhydrous sodium acetate, adding water, and finally washing until the oil was neutral. By cold saponification with two hours' contact: - 1.5066 gram, required 0.3164 gram. KOH ... S.N. = 210.

This gives an ester value of 73.5, calculated as geranyl-acetate. As 59.99 per cent. of ester was originally present, this represents 13.51 per cent. of ester formed by the free geraniol present. The free geraniol in the oil was thus 10.6 per cent. and the ratio combined geraniol/total geraniol = 81-100.

Corresponding duplicate determinations were obtained in each case.

It thus appears that other esters found in Eucalyptus oils were practically absent in that of this species, and all our results support this conclusion. At any rate, they can only occur in very small quantity at any time.

The Geraniol. - The pure alcohol was prepared by saponifying the oil in the cold and then combining it with dry calcium chloride. The compound C10Hl8O, CaCl2 was then ground up with benzene, freed from liquid by means of the pump, and finally washed with dry ether. It was then decomposed by water, the oil washed, and finally steam-distilled.

The resulting product was colourless, had a rose-like odour, was inactive, had specific gravity 0.885, and boiled at 224-2250 C. (uncorr.).

A portion was oxidised by using potassium bichromate and sulphuric acid in the usual way and the product combined with sodium bisulphite, the crystalline mass purified and decomposed. The separated oil had an odour of citral and formed the citryl-/3-naphthocinchoninic acid melting at 199-2000 C.

The Acid of the Ester. - The aqueous portions remaining from the saponifications were mixed together, the whole evaporated almost to dryness, and distilled with dilute sulphuric acid, adding fresh quantities of water until the volatile acid had all come over. A portion of the distillate was exactly neutralised with barium hydrate solution, evaporated to dryness, heated in air oven to render the salt anhydrous, and finally igniting with sulphuric acid. 0.828 grams gave 0754 grams barium sulphate = 91.06 per cent. A second determination gave corresponding results.

Barium acetate theoretically gives 91.37 per cent. barium sulphate, a result which indicates that a very small amount of another volatile acid than acetic was present in the oil as ester. When the barium salt was first decomposed the odour suggested valeric acid as well as acetic, and as valeric acid ester is a common constituent in Eucalyptus oils, it may thus occur in traces in the oil of E. Macarthuri.

The remainder of the distillate was exactly neutralised with sodium hydrate and evaporated to crystallising; well-formed crystals of sodium acetate were thus obtained.