176 E. HURST, H. G. SMITH AND J. READ. 
A CONTRIBUTION TO THE CHEMISTRY OF THE 
PHELLANDRENEKS. 
By Eric Hurst, HENRY GEORGE SMITH, and JOHN READ. 
[Read before the Royal Society of N. S. Wales, November 1, 1922 | 
In the course of his well-known investigations on the 
phellandrenes, Wallach established the complete chemical 
and physical identity of the dextro-gyrate phellandrene of 
elemi oil with the dextro-gyrate phellandrene of bitter 
fennel oil. Further, the levo-gyrate phellandrene of the 
essential oil of the so-called Hucalyptus amygdalina was 
characterised by him as the optical antipode of the first- 
named phellandrene. These phellandrenes were accord- 
ingly named d-a-phellandrene and I-«-phellandrene, respect- 
ively, whilst the dextro-gyrate phellandrene of water fennel 
oil was named d-f£-phellandrene (Annalen, 1904, 336, 9; 
**Terpene und Campher,’’ 1914, 486). 
The characterisation of these very closely related ter- 
penes was accomplished largely by a study of their nitrites: 
these are well defined crystalline derivatives, easily 
obtained by the action of nitrous anhydride upon solutions 
of the hydrocarbons in light petroleum at 0°. Schreiner 
(Pharm. Arch., 1901, 90; Chem. Soc. Abstracts, 1901, 80, i, 
600) showed that the I-«-phellandrene of eucalyptus oils 
yielded in this way a mixture of two nitrites having distinct 
melting points and optical rotatory powers. In confirming 
Schreiner’s observation, Wallacb isolated an ¢-nitrite, 
melting at 113—114° and a /-nitrite, melting at 105°, from 
the levo-gyrate o-phellandrene of eucalyptus oil. The 
melting point recorded by Schreiner for the less soluble 
a-nitrite was, however, 120—121°; so that a considerable 
