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OCCURRENCE OF TERPENE TERPINENE. 
On THE OCCURRENCH oF THE TERPENE TERPINENE 
IN THE OIL oF Eucalyptus megacarpa. 
By HENRY G. SMITH, F.C.S. 
[Read before the Royal Society of N.S. Wales, December 4, 1918. ] 
TERPINENE was first recognised as a definite terpene by 
Wallach,! and has, so far, been detected only in a very few 
essential oils. It was first discovered by Weber? in carda- 
mom oil, and has been recorded as occurring in marjoram 
oil, dill oil, coriander oil, and a few others. Terpinene is 
thus rarely found existing naturally, and Gildemeister and 
Hofimann® have stated “that it may appear doubtful 
whether this terpene is really found in nature or whether 
it is formed by the influence of heat during the distillation 
from other compounds contained in the respective oils.”’ 
This opinion cannot now be supported in reference to 
Hucalyptus oils, because if true the terpene would without 
doubt, have been detected in them before this, seeing that 
the oils of such a large number of species have now been 
determined. It must, therefore, be considered as a natur- 
- ally occurring terpene in some Kucalyptus oils. 
Terpinene is formed artificially by the action of alcoholic 
sulphuric acid on many of the terpenes and terpene deriva- 
tives, ordinary turpentine (pinene) being well adapted for 
the purpose. It may also be prepared by similar means 
from terpineol, geraniol, dihydrocarveol and cineol. This 
formation is interesting in this connection as, besides cineol 
and the terpenes pinene and limonene, geraniol appears 
to be present also as an ester in the oil of Eucalyptus 
megacarpa. 
1 Ann. Chem., (230) 254 and 260. 2 Ann. Chem., 238, (1887) 107. 
* «The Volatile Oils,” p. 119 (English translation, 1900). 
Hu—December 4, 1918. 
