NEW AROMATIC ALDEHYDE OCCURRING IN EUCALYPTUS OILS. 289 



So far as the Eucalypts of New South Wales are concerned, it 

 is now fairly well known in which particular species any con- 

 stituent occurs in greatest amount. This fact was taken advantage 

 of in the preparation of this aldehyde. Our researches had shown 

 that this aldehyde occurs probably in greatest amount in the oil 

 obtained from E. hemiphloia. Our sample of E. hemiphloia had 

 been obtained from Emu Plains. But as this species grows in 

 abundance at JBelmore, in the neighbourhood of Sydney, and this 

 locality is easy of access, fresh material was obtained from there, 

 with the result that the oil was found to be practically identical 

 with that obtained a year previous from Emu Plains. 



It is well known that the oil of E. cneroifolia of South Australia 

 is rich in eucalyptol. In the fraction of the oil of E. hemiphloia 

 distilling below 183° C. (representing 73 per cent, of crude oil) 24 

 per cent, of eucalyptol was found, while the same fraction of the 

 oil of E. albens contained 37 per cent, of eucalyptol. Our results 

 indicate that in the majority of instances the maximum amount 

 of eucalyptol in Eucalyptus oil is reached during the fall of the 

 year and towards the winter months, but that as the spring 

 advances and the trees become more vigorous in growth, the 

 minimum amount of eucalyptol is present, while the yield of oil 

 obtainable from the leaves is greater, the tendency being for the 

 constituents to form eucalyptol as the year advances. 



When the pure aldehyde was treated with an alkaline solution 

 of potassium permanganate, oxidation took place rapidly with the 

 generation of a considerable amount of heat. One of the products 

 thus formed was apparently eucalyptol, and although (owing to 

 want of sufficient material) it has not yet been isolated so that its 

 physical characters might be determined, yet, from its charac- 

 teristic odour and pungency I have no doubt but that eucalyptol 

 is formed when the aldehyde is thus treated. Several determin- 

 ations were made and always with the same result. When the 

 oxidation was carried out with potassium bichromate in sulphuric 

 acid, the acid formed was quite different from that obtained by 

 potassium permanganate ; eucalyptol was not formed by this 



