Resins They cannot be defined clearly. They can be described as mixtures of organic acids, alcohols, and esters. Physical Properties: They are amorphous, non- crystallizable, transparent, solids or semi-solids. They are insoluble in water & soluble in organic solvents. When heated they melt & burn with a sooty flame. They are produced in plants in the special type of glands. On boiling with alkalis they form resin soaps. They are nonnitrogenous. They are hard, heavier than water and nonconductive. On trituration with water they form emulsion Classification: - According to the principal components present, they can be classified as follows:- Class. Drug. Examples. 1 Acid Resin. Colophony, Myrrh. Abietic acid, Commiphoric acid. 2. Ester Resin. Benzoin, Storax. Benzyl benzoate. Benzyl cinnamate. 3. Resin alcohols. Balsam of Peru, Gurjanbalsam Peruresinotannol, Gurjuresinol. Resin Combinations: - 1 ) Oleoresins : - Homogeno