PINENES OF THE OILS OF THE GENUS EUCALYPTUS. 199 



stated that the hydrocarbon, eucalyptene, from Eucalyptus 

 globulus, is identical with dextropinene. 



In 1895 Bourchardat and Tardy 1 carried out experiments with 

 the hydrocarbon found occurring in small quantity in the oil of 

 Eucalyptus globulus, and arrived at the conclusion that it has the 

 properties of laevorotatory terebinthene found in French oil of 

 turpentine, but with an almost equal opposite rotation. They 

 give its boiling point as 156 - 157° C; its density as 0'870 at 0° C. 

 and 0*865 at 18° C; and its specific rotation at 15° C. as [a] D + 39°. 

 They give Riban's determination 2 for the specific rotation of lsevo- 

 rotatory terebenthene as - 40 "3°. It appears, therefore, from the 

 results obtained by these authors on this hydrocarbon from the 

 oil of E. globulus, and those obtained in this research on the same 

 hydrocarbon from the oil from E. dextropinea, that these dextro- 

 rotatory pinenes obtainable from members of two distinct groups 

 of Eucalypts are identical, and that the dextrorotatory pinene 

 from the whole genus Eucalyptus, is a physical isomeride of the 

 lsevorotatory pinene (terebinthene) obtained from French oil of 

 turpentine, and possibly also of the lsevorotatory pinene of the 

 Eucalypts, although this lsevo form has, so far as observed, a higher 

 specific rotation. 



As phellandrene has not yet been detected in an Eucalyptus 

 oil containing a highly dextrorotatory pinene, and as the opposite 

 highly lsevorotatory pinene has been found existing with phellan- 

 drene in several members of the Stringybark group of Eucalypts, 

 it appears that we must arrive at the conclusion that the dextro- 

 rotatory pinene is present in greater abundance in Eucalyptus oils 

 of the globulus type, and that are rich in eucalyptol, particularly 

 as those oils are usually dextrorotatory, and eucalyptol having no 

 rotation, the activity must necessarily be due to the terpenes. 

 Although it had been assumed that terpenes having right and left 

 rotation were probably present in these oils, yet, no proof had 

 previously been forthcoming that this was so, and the isolation of 



1 Compt. rend. 1895, 120, 1417-1420. 

 2 Comp. rend. 78, 788 ; 79, 314. 



