ALMONDS, VOLATILE OIL OF, better known as BENZALDEHYDE Or OIL OF BITTER ALMONDS, C,11X110. The cake which is left after the expression of the fixed oil from hitter almonds contains, among other matters, two substances called, respectively, amygdalin, and emulsin or synaptase. When the cake is bruised and made into a paste with water, the synaptase acts as a ferment upon the amygdalin, splitting it up into the volatile oil of almonds, hydrocyanic (prussic) acid, and grape-sugar. The oil is not originally present in the bitter almonds; in fact, the latter do not contain a trace of the oil ready formed, so that the oil is purely the product of the fer mentation of amygdalin. This action takes place very rapidly, and is complete in twenty-four hours. The paste having been placed in a retort, heat is very cautiously applied, to prevent the lumping and frothing to which the almond infu sion is liable. In the distillation, the hydrocy anic acid and the volatile oil unite in an unstable compound which passes over into the receiver, along with much water. The crude oil thus obtained decomposes gradually, the prussic acid being set free, and on this account it is very poisonous, many fatal cases having occurred from its willful, accidental, or careless use. The
crude oil may be purified and freed from prussic acid by means of ferrous chloride and lime. The volatile oil is the aldehyde of hen zoie acid into which substance it gradually changes when exposed to the air in a moist state. It is colorless, has an agreeable odor, and an acrid, bitter taste. It is soluble in water to the extent of 1 part in 300 parts of water, but mixes in all proportions with alcohol and ether. It is a highly refractive liquid, of specific gravity 1.05 at 15° C.; it boils at 179° C. At present it is usually prepared by boiling ben zyl chloride with an aqueous solution of lead nitrate. The crude product thus obtained is shaken with a solution of acid sodium sulphite, which forms a crystalline compound with ben zaldehyde, while the impurities remain in solu tion. Pure benzaldehyde is obtained from the crystalline compound by the action of dilute acids. The oil is used by the confectioner and the perfumer, and is employed on a large scale in the manufacture of benzoic and cinnamic acids and of various dyes.