154 R. B. Dreiv and E. I. Rosenhlum . 



The System cineol-ciiral. 



The Fhellandrene Comj)lex. 



We hoped by these methods to obtain from the rotation of a 

 Eucalyptus oil an indication of the amount of phellandrene it 

 contained, and a series of l-pliellandiene-cineol mixtures were 

 made up. The preparation of the phellandrene has been else- 

 where^ described, and its constants were — 

 a = -68.35° 

 tx^,= .8454 



8.,5= 1.4747 



The results were rather surprising, for we found that if the 

 measurements be taken immediately after mixing, the density and 

 rotation agree closely with the calculated values, and the refrac- 

 tive index exactly, but the mixtures are unstable, rapidly decreas- 

 ing in rotation, and increasing in density and refractive index. 



This change goes on most rapidly in the presence of light and 

 oxygen, more slowly in the dark, and not at all, as far as we were 

 able to make out, in the absence of oxygen. 



Phellandrene itself rapidly changes under similar conditions, 

 attaining equilibrium when its rotation is about -|-3o. We hope 

 to discuss this matter more fully in a future paper. 



The System l-phellandkene — cineol. 



1.4579 



.9202 



R. Barr.v Drew. Australian Association for the Advancement of Science. Report 1913. 



