ALMONDS, VOLATILE OIL OF, OR ESSENTIAL OIL OF. The cake which is left after the expression of the fixed oil from hitter A., contains, among other matters, a portion of two substances, called, respectively, arnygdalin, and emulsion or, synaptase. When the cake is bruised and made into a paste with water, the synaptase acts as a ferment upon the amygdalin, and 1 atom of the latter resolves itself into 2 atoms of volatile oil of bitter A., 1 atom hydrocyanic (prussic) acid, 1 atom of grape-sugar, 2 atoms formic acid, and 7 atoms of water. This paste is placed in a retort, and allowed to stand for 24 hours, when beat is cautiously applied and distillation carried on. The volatile oil rises in vapor, and passes over into the receiver, accompanied by much water, and contaminated with a con siderable amount of prussic acid. The oil is not originally present in the bitter A.; in fact, the latter do not contain a trace of the oil ready formed, so that the oil is purely the product of the fermentation of amygdalin, 100 parts of which yield 47 of crude oil. Commercial oil of bitter A. has a golden yellow color, but may be purified so as to be almost colorless. The crude oil is very poisonous, owing to the prussic acid dissolved therein, and many fatal cases have occurred from the willful, accidental, and careless use of the oil. It is unfortunate that the manufacturers of the volatile oil should not sub
ject the crude oil to the action of lime and an iron salt, and then re-distill, when the prus sic acid would be left fixed by the lime and iron, and the pure volatile oil be alone obtained in the receiver. As so procured, the pure oil is not a dangerous poison. The oil has an agreeable odor, an acrid, bitter taste, and burns with a smoky white flame. It is heavier than water, being of the density of 1083; is soluble in water to the extent of 1 part in 30 parts of water, mid is very soluble in alcohol and ether. Heated to 356° F., it boils, and distills over unaltered ; and, exposed to the air, it is gradually oxidized into benzoic acid. The oil Is tailed by tho chemist the hydride of benzoyle. In medicine the volatile oil is used in place of prussic acid, but is very variable in strength, being sometimes four times the strength of medicinal prussic acid. The dose is a quarter of a crop to a drop and a half in an emulsion. The cook and confectioner employ the oil for flavoring custards, etc., and the perfumer uses it for scenting toilet-soap, etc.