Physical Chemistrt/ of Essential Oils. 



159 



Molecular Kefkactive Power n-lld.M 



Molecular Eefractions at 20° 



a. Found [w^ - l/(n2 + 2)rf . M formulaj 



b. Calculated from Atomic liefractionsi 



Substance. 

 1-phellandrene 

 d-pinene 

 1-pinene 

 pinene 

 d-limonene 

 cineol 

 eugenol 

 safrol 

 terpineol 

 citral 



of atomic refractions, and these have been used to calculate the 

 theoretical molecular refractions. As will be seen, these are in 

 excellent agreement with the experimental values in some cases, but 

 in others, as in that of citral, where the constants of the sample 

 showed it to be of quite satisfactory purity, the large divergence is 

 difficult to account for. In the cases of eugenol, safrol, and ter- 

 pineol, it may be due in part to the unknown influence of ring 

 formation. 



The value for phellandrene lends some support to Wallach's 

 formula for that terpene, in that it indicates two double Ijonds. 



(3) The Rotation. 



Considerable attention has been devoted to the influence of tem- 

 perature on rotation, and from the work of a number of chemists 

 it appears that the rotation of solids dissolved in non-active sol- 



1 Eis^nlohr. Zeit. Physik. Chem., 1911, 



