The plant contains some tannic acid, together with a resin and a bitter principle and a volatile oil. The chief constituents of the oil are Borneol, bornyl acetate and other esters, a special camphor similar to that possessed by the myrtle, cineol, pinene and camphene. It is colourless, with the odour of Rosemary and a warm camphoraceous taste. The chief adulterants of oil of Rosemary are oil of turpentine and petroleum. Rosemary yields its virtues partly to water and entirely to rectified spirits of wine.