464 H. G. SMITH. 
On THE BUTYL ESTER or BUTYRIC ACID occURRING 
IN SOME HUCALYPTUS OILS. 
By HENRY G. SMITH, F.C.S. 
Assistant Curator of the Technological Museum, Sydney. 
[Read before the Royal Society of N. 8S. Wales, December 2, 1914. | 
IN a paper by the Curator (Mr. R. T. Baker, F.L.S.) and 
myself, read before the British Association for the Advance- 
ment of Science when that body met in Sydney in August 
last, the announcement was made that a previously unde- 
scribed ester, with a low refractive index, occurred in 
some quantity in the oil of Eucalyptus Perriniana, collected 
both in Tasmania and in New South Wales, and that the 
presence of this ester in such quantity was one of the dis- 
tinguishing features for this species when compared with 
the closely related one, EH. Gunnii. Considerable work 
was done on these species with material collected at both 
localities, and it is evident from the results that these two 
EKucalypts are not identical. 
It is the purpose of this paper to record the chemical 
results obtained with this ester, which is evidently a con- 
stant constituent in the oils of a certain class of Kucalypts, 
although in most cases occurring but in small amount. 
This is another instance of the peculiarity, so pronounced 
with chemical constituents in the genus Hucalyptus, namely 
a progressive increase throughout a whole series of closely 
agreeing forms until the maximum is reached in one of 
them. Not only is this the case with the oils, but with 
the exudations and other secretions also, the sequence 
running through a whole group being sometimes remark- 
ably complete. 
