A CONTRIBUTION TO THE CHEMISTRY OF THE PHELLANDRENES. 177 
discrepancy exists between the two temperatures quoted 
for the melting point of this substance. 
Wallach states (loc. cit., p. 16) that although mixtures 
of the a- and £-nitrite show little change in melting point, 
as compared with the pure substances, it is nevertheless 
easy to discriminate between the two individual substances 
and their mixtures by observations of optical rotatory 
power. According to Wallach, the 4-nitrite of l-4-phellan- 
drene (from eucalyptus oil) in chloroform solution gave 
[a], +142°6° and [a], +135°93°, whilst Schreiner obtained 
the value [«], +123°5°. Similarly, for the corresponding 
B-nitrite Wallach recorded the values [«]) —40°817° and 
[a], —40°287°, whilst Schreiner obtained [«], —36° for a 
preparation melting at 100—101°. Values closely corres- 
ponding in magnitude were recorded for the two nitrites 
prepared from the d-c-phellandrene of bitter fennel oil, the 
sense of the optical rotation being, of course, reversed. 
The extremely important role of the nitrites, in a study of 
the chemistry of the phellandrenes, need not be elaborated 
further for the purposes of the present paper. 
During investigations on components of the essential oil 
of Eucalyptus dives we were led to prepare specimens of 
the nitrites of the l-a-phellandrene of which this oil is so 
notable a source. As a consequence, it was found possible 
to isolate without difficulty specimens of [-phellandrene 
a-nitrite melting at 121—122°, with decomposition. Such 
specimens, when dissolved in chloroform to form solutions 
of the approximate concentration indicated by Wallach, 
and submitted without delay to polarimetric examination, 
yielded results agreeing satisfactorily with the values 
quoted above. It was noticed, however, that the originally 
colourless solutions became pale yellow and finally brown, 
or reddish-brown, when kept. Polarimetric examination 
showed that the change in colour was in all instances 
L—October 4, 1922. 
