Benzoin is sparingly soluble in chloroform, only partially so in ether, and completely in alcohol. On mixing the alcoholic solution with water, the resin is separated. Petroleum-ether and benzine withdraw only benzoic acid from the dry, powdered benzoin. All varieties of benzoin dissolve in concentrated sulphuric acid to a beautiful purple colored fluid, from which benzoic acid, if present, is separated in crystals by the gradual addition of water. The establishment of the presence of cinnamic acid is best effected as follows: Boil the sample in milk of lime, filter, and treat the solution with hydrochloric acid. The precipitate thereby separated is thoroughly washed, triturated with potassium permanganate and water, and heated, whereby in the presence of cinnamic acid, oil of bitter almonds is formed from the latter, which is readily recognized by the odor. If benzoin containing benzoic acid be heated, white vapors are emitted which, on cold surfaces, deposit in very delicate, lustrous, acicular, or foliated crystals of benzoic acid, the so-called benzoin flowers (_Floris benzoes_.) Benzoic acid thus prepared possesses an agreeable, vanilla-like odor, since by heating the benzoin the greater portion of the odoriferous substance contained in it escapes. Benzoic acid separated by the wet method is odorless. Benzoin is especially used for fumigating pastilles. It is also of great importance on account of its property of preventing fats from becoming rancid, if added to them in small quantities.