72 H. G. SMITH. 



On the AMYL ESTER of EUDESMIC ACID, occurring in 

 EUCALYPTUS OILS. 



By Henry G. Smith, p.c.s., Assistant Curator, Technological 

 Museum, Sydney. 



[Read before the Royal Society of N. 8. Wales, Jane 6, 1900.'] 



In a paper by Mr. R. T. Baker and myself " On the Stringy bark 

 Trees of New South Wales," read before this Society, July 1898, 

 we show that an ester must be present in the oil of Eucalyptus 

 macrorhyncha. We had several times detected the presence of 

 esters in other Eucalyptus oils but always in too minute quantities 

 to allow them to be isolated with any success. 



The investigation into the constituents of these oils, now being 

 undertaken on material obtained from undoubted species, enables 

 the statement to be made, that most probably esters are present 

 in all Eucalyptus oils, and it is to be supposed, therefore, that to 

 these the characteristic odour of Eucalyptus oil is largely due. 



There is an organic connection between the constituents of the 

 oils of the genus Eucalyptus, and it appears almost certain that 

 most if not all of those constituents occurring in minute quantities 

 in the oils of some species, are present in larger amount in the oils 

 of other species. It is certainly so with the two pinenes present 

 in these oils, with lsevo-phellandrene, 1 with eudesmol, with (^cumin- 

 aldehyde, with eucalyptol and with other constituents which have 

 been isolated during this research ; the chemistry of these, how- 

 ever, is not yet completed. 



The ester that forms the subject of this paper has been detected 

 in several oils in increasing amount. The oil of the "Black Gum" 



1 Investigation of the oils of most of the New South Wales species of 

 Eucalyptus points to the fact that dextro-phellandrene does not occur in 

 these oils. 



