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Brea Gum.—This substance, which has been proposed as a substitute for gum arabic, is believed to be derived from Caesalpinia praecox, a Brazilian tree. It occurs in stalactitic pieces or oval reddish-yellow tears, isolated or agglomerated. It forms with water a viscous, pale reddish-yellow mucilage, of acid reaction, which may be partially decolorized by heating with a few drops of hydrochloric acid. It is said to contain 77 per cent. of arabin.