 Other methods of separation involve introducing an additional agent, called an "entrainer", that will affect the volatility of one of the azeotrope constituents more than another.When an entrainer is added to a binary azeotrope to form a ternary azeotrope, and the resulting mixture distilled, the method is called azeotropic distillation.The best known example is adding benzene or cyclohexane to the water/ethanol azeotrope.