NEW AROMATIC ALDEHYDE OCCURRING IN EUCALYPTUS OILS. 287 



colourless and often water-white, especially when rectified; they 

 usually also contain very little eucalyptol. 



Now oils rich in this aldehyde do not appear to contain phellan- 

 drene, as it is not found in the oils of the "boxes" above mentioned, 

 but it does not follow that phellandrene is always absent in the 

 oils of species which contain this aldehyde, in minute quantity, 

 because in several both these constituents have been found together. 

 Phellandrene is a most unsatisfactory constituent when only 

 occurring in small quantity in the oil of any species of Eucalyptus 

 at certain times of the year; as at other times of the year no 

 phellandrene can be detected in the oil. It appears to be very 

 unstable, and this fact must always be taken into consideration. 



The oils from the "boxes" above named, although containing 

 no phellandrene, and but little pinene, were all lsevorotatory, 

 showing that the rotation must be due to the presence of some 

 substance having a high boiling point, and as the principal con- 

 stituent in the higher fractions appeared to be this aldehyde, it 

 was assumed that the rotation must be due to that substance, and 

 this has been proved to be the case. 



The optical rotations in a 100 mm. tube for the oil of E. hemi- 

 phloia, obtained in September, were as follows : — 



Crudeoil = -6-8° 



Fraction boiling below 183° = - 3'2 



Fraction 183 - 215° C = - 10'3 



Fraction 215-230° C = - 250 



The optical rotations in a 100 mm. tube for the oil of E. albens, 

 obtained in June, were as follows : — 



Crudeoil = -6*5° 



Fraction boiling below 1 83° C = -5-6 



Fraction 183 - 225° C = -6-0 



Fraction 225 - 255° C = - 14'6 



Corresponding results were also obtained from the oils of 

 several other species. 



The reason why the oil of E. cnerifolia of South Australia is 

 lsevorotatory is now explained, it is due to the presence of this 



