The acetic Acid ester. The amount of ester occurring in the oil of this species 

 is somewhat large, and as the redistillation had demonstrated the presence of 

 acetic acid, which had been derived from the decomposition of an ester, it 

 was decided to proceed further, particularly as the amount of the free acid present 

 in the crude oil was quite small. A quantity of the crude oil was boiled for some 

 time with aqueous potash under a condenser, the aqueous portion separated, 

 evaporated down and filtered. It was then acidified with sulphuric acid, and 

 the volatile acids distilled over until all had been obtained. Qualitative tests 

 showed that acetic acid was present in quantity, but the odour of valeric acid 

 had also been detected, so that it is most probable that both acids were present. 

 (See also the article on the Valeric Acid Ester in Eucalyptus Oils.) 



The distillate was exactly neutralised with barium hydrate solution, and 

 the mixed barium salt purified and prepared in the usual manner. The amount 

 of barium was then determined as barium sulphate ; 0-4858 giam. of the 

 barium salt on ignition gave 89-3 per cent, of BaSO 4 , so that the amount of barium 

 acetate in the mixed salt was 90-85 per cent., and the barium valeriate 9-15 per 

 cent., assuming that valeric acid was the only other acid present besides acetic. 

 This result suggests that valeric acid may be present as an ester in many crude 

 Eucalyptus oils, and to be connected with the valeraldehyde which occurs so 

 frequently in certain groups. Acetic acid is the free acid occurring in Eucalyptus 

 oils, which is demonstrated in the article dealing with this subject, and it is also 

 present in the oil of E. Macarthuri, E. acervula, and other numerous species as 

 an ester in combination with geraniol. The alcohol of the ester occurring in 

 the oil of E. carnea has now been determined, and that it is not geraniol is 

 shown by the ester not saponifying in the cold when treated with alcoholic potash ; 

 it was proved to be dextro-rotatory terpineol. The portion boiling above 

 190 C. was saponified and the separated oil distilled under reduced pressure. 

 A portion was eventually obtained boiling at 99-103 C. at 10 millimetres. This 

 had specific gravity 0-93; rotation D + 60; refractive index at 20 = 1-484, 

 and gave a fair yield of phenylurethane melting at 110 C. This is further 

 evidence that terpineol was formed early in the genus, similarly with geraniol, 

 and probably continues throughout the oils of the entire group. 



17. Eucalyptus dextropinea. 



(R.T.B., Proc. Linn. Soc., N.S.W., 1898, p. 417, t. XI.) 

 A Stringybark. 



Systematic. A tree attaining a height of from 60 to 100 feet or higher, 

 and a diameter up to 5 feet. Bark dark or black on the outside, fibrous, and 

 longer in the fibre than that of E. leevopinea. Branches smooth for a considerable 

 distance down, but this feature varies. Leaves almost identical with those of 

 E. lavopinea of this work, and resembling also those of E. obliqua, L'Her. 

 Abnormal leaves broad, rounded at the base, and very acuminate, opposite or 

 nearly so, on a short petiole, the venation well defined, the intramarginal vein 

 being much removed from the edge. Normal leaves lanceolate, falcate, acuminate, 

 often very oblique, shining on both sides, rather thick, the intramarginal vein 



