The vapor-liquid equilibria (VLE) of the systems, ethanol-water, ethanol-water-ethylene glycol and ethanol-water-ethylene glycol-CaCl2, at finite concentration and normal pressure were measured. The experimental results showed that ethylene glycol with added salt was more effective than ethylene glycol without salt for separating ethanol and water by extractive distillation. A set of experimental apparatus has been established to measure the relative volatilities of C4 (including butane, 1-butene, 2-trans-butene, 2-cis-butene and 1,3-butadiene) at infinite dilution by the inert gas stripping and gas chromatography method. It is verified that adding a little salt to the! solvents can improve the relative volatilities of C4, and the effect is apparent compared with other organic solvents. Either polar or non-polar systems can be separated by extractive distillation with salt, which is a convenient method for separations to be carried out in industry.