206 H. G. SMITH. 



on redistillation, no less than 77 per cent, below 165° 0., (see 

 table), whereas in the polymerised oil only 7 per. cent, was obtained 

 below 165° C, or tabulating the results : — 



160° 0. to 162° 



C. 



= 3 per cent. 



162 „ 165 





= 7 



165 „ 167 





= 25 



167 „ 172 





= 58 



172 „ 178 





= 64 



The fraction obtained between 165° 0. and 178° C. was found 

 to have been reduced in rotatory power by about half. Originally 

 the rotation for the whole fraction on the first distillation was 

 + 66-5° in a 200 mm. tube. After polymerisation of the oil the 

 rotation in the same tube was + 32*3°. Evidently the polymeri- 

 sation had not been complete. 



From the results of the above determinations it is apparent 

 that these Eucalyptus pinenes are chemically identical with tere- 

 benthene and australene, and only differ from them by having 

 greater rotation. We thus arrive at the conclusion that the 

 pinenes from the oils of the Eucalypts (N.O. Myrtacese), appear 

 identical with those obtained from Pinus (N.O. Coniferse). 



As the Eucalyptus pinenes lend themselves so readily to poly- 

 merisation by acid, and as the crude oils from all the Eucalypts 

 contain organic acids in some form, it is probable that certain 

 constituents found in Eucalyptus oils are the result of a process 

 of natural polymerisation of these pinenes in the oil cells of the 

 leaf. It may be that eventually structural differences in the 

 molecule may be determined between the Eucalyptus pinenes and 

 those obtained from the Coniferse, as indicated by the natural 

 alteration products. Further research may decide this, but it 

 does not appear that we shall receive much assistance from the 

 preparation from these pinenes of known chemical compounds, 

 because they, so far, have proved themselves identical with those 

 obtained from the pinenes from the Coniferse. 



