196 Proceedings of the Royal Society of Victoria. 



to all the oils has been Cahours' nitrite reaction for Phellandrene 

 [Ann. der Chem. 41, p. 76), as modified by Bunge iyZeit. fur 

 Chem. 5.; Bull. Sac. Chim. 1870, pp. 272-273) and Wallach and 

 Gildemeister {A;ih. der Chem. 246, p. 282). 



The densities were taken with a pyknometer holding about 

 25 grammes of water, and in each case at 15°C., referred to water 

 at 15°C. The specific rotation was measured in a column of 

 liquid 10 cm. in length at 15°C., using the Sodium-flame; if a is 

 the angle of rotation and d the density, then the specific 

 rotation in the usual notation is 



w» - r 



The refractive index was measured at 20 "C. for the d line of 



Sodium with a spectrometer read to minutes but not to fractions 



of a minvite, the index in each case being calculated from three 



independent measurements of the angle of deviation 8 according 



to the usual formula 



. A + h 

 sm. -^ 



fx, = - where A is the angle of the prism. 



sin. — 



To obtain the specific refractive energy 



at 20' 



d ^ \ d 



being only slightly variable with temperatui-e j^ the densities at 

 20° were calculated from those determined at 15" by means of 

 the formula ^20° = ^i5°(l "" ^^) where l> is the coefficient of change 

 of density of the oil for 1°C. ; d was determined for four oils by 

 means of measui'ements of their densities at 15° and 100°C. as 

 now given. 



Table I. 



