BENZOIN, in chemistry, a gum called gum Benjamin ; is brought from the East Indies in brittle masses of unequal degrees of purity, and varying in colour from yel low to white. It has but little taste ; but if previously dissolved, it is rather pun gent and aromatic. Its smell is grateful when rubbed or warmed, and when the heat is increased the resin melts, a white and most fragrant vapour rises, which is easily condensed on the surrounding bo dies into beautiful shining saline needles. These are what are denominated benzoic acid. Benzoin is very soluble in alcohol, but separates on the addition of water. It is one of the most important balsams in modern chemistry, which are consider ed as resins naturally united with that vo latile crystallizable acid which has just been mentioned, and which is the same in all natural balsams. The benzoic acid may be prepared either by sublimation or by digestion : that obtained by sublima tion is remarkably light, feathery, and elastic. When pure, it is quite white ; for the yellowness is owing to its admix ture with oil. This acid is contained in
styrax and balsam of Tolu, giving them the characters of true balsams. It is like wise met with, but more sparingly, in se veral fragrant barks, resins, and other vegetable matters. It generally appears in its proper character when these sub stances are moderately heated ; or it may be extracted with lime. Benzoic acid, or, as it is called in the shops, flowers of Benjamin, is the chief ingredient of the celebrated "pomade divine," of which, according to Dr. Beddoes, the composi tion is as follows : oz. steeped in water ten Beef marrow 12 days, and afterwards in rose-water 24 hours.
Flowers of Ben jamir ' of each i an ounce.
Pounded storax Florentine orris Cinnamon Clove and nutmeg * ditto.
The whole to be put in an earthen vessel, closely covered down to keep in the fumes, and being suspended in water made to boil three hours. After which the whole is to be strained and put in bottles.