35° A COMPENDIUM OF 
As arule, with few exceptions, only one vol- 
atile oil is obtained from the plant. The orange 
tree yields one oil from the fruit, another from 
the flower (Neroli), and again another from the 
unripe fruit and leaves. Volatile oils are di- 
vided by chemists into non oxygenated (as co- 
paiba and turpentine, which are exclusively 
composed of C,, H,,). Oxygenated oils in- 
clude the greater part of the aromatic oils and 
the sulphuretted, or those oils containing sul- 
phur, as the mustard and horseradish, C, H; 
N.S. 
The volatile oils are capable of rotating the 
plane of polarization either to the right or left 
hand. An exception to the rule is the Ameri- 
can and French oil of turpentine; the former 
rotates the plane of polarization to the right, 
whilst the latter turns to the left. This means 
of distinguishing one turpentine from another 
is not always a feasible one, even when you can 
command the instrument called the polariscope. 
The volatile oils are made up of two principles, 
termed oleopten and stearopten, the former 4 
true hydrocarbon, lighter than water and very 
volatile, and the latter a solid, resembling cam- 
phor in general character, and, as a rule, heav- 
ier than water, containing oxygen with an aver- 
age specific gravity of about 0.95. The colors 
of the volatile oils are said to be due to the 
