372 A COMPENDIUM OF 
which when freshly distilled is without color, 
but on standing assumes a brown-red tinge. 
Odor fragrant; taste pungent and aromatic, 
and of neutral reaction. The oil has a greater 
specific gravity than any in the list, being about 
1.094. The hydrocarbon Safrene composes 
about nine-tenths of the whole; the balance is 
Safrol, an oxydised compound, which is capable 
of crystallizing in six-sided prisms. The oil is 
used only as an external remedy, in form of 
liniments; rotating power very feeble, slightly 
dextrogyre. 
Oleum Sinapis, Mustard Oil. Obtained 
from the Sinapis Nigra.—Natural order Cruci- 
fere, There are two oils existing in the Black 
Mustard seeds, fixed and volatile; the latter is 
obtained after the expression of the former, 
then the seeds are mixed with water and dis- 
tilled. This very volatile substance, which 
seems to awaken in all its pungency in contact 
with water, is usually colorless, or of a pale 
straw color; specific gravity, 1.018; boiling at 
298° F. The odor is powerfully pungent; it 
has an intensely acrid, burning taste, and when 
applied to the skin, blisters at once. The oil 
forms, with alkaline solutions, sulphocyanates. 
The activity of the volatile oil is due, it is said, 
to the myrosin (a ferment) coming in contact 
with sinigrin (myronate of potassium) under 
the influence of water. The White Mustard 
seeds yield compounds of entirely a different 
nature, and the chemistry of the two are inter- 
esting (see Dispensatory). The volatile oil of 
mustard has been made artificially by treating 
