Physical Chemistry of Essential Oils. 



1. The influence of temperatuie change on tlie density, refrac- 

 tive index, and rotation of a nunil)er of terpenes and allied sub- 

 stances has been studied. 



2. In the cases of density and refractive index the temperature 

 coefficients all lie close together, while the divergences from a linear 

 relation are slight. 



3. Laevo-phellandrene, as obtained from the oil of Eucalyptus 

 dives, is in all its relations somewhat abnormal, and the suggestion 

 is made that it may form associated molecules at the lower tempera- 

 tures. 



The thanks of the author are due to Dr. Heber Green for the 

 interest he has shown in this research. 



