把装有稀蔗糖溶液、底端封以半透膜的管子竖直放入装有纯水的大池子中，达到平衡时糖水液面高于池中的纯水 液面.如果此时在管子的中部再加一半透膜，构成双半透膜-溶液系统，管子顶部会不会有纯水冒出且其液面高于池中液面呢? 热力学分析表明:对于蔗糖水浓度随高度变化的平衡溶液，不会;对于浓度不随高度变化的均匀溶液，会! 但是后者并不违背 热力学第二定律.

The pipe filled with 3% sugar solution and closed by the semipermeable membrane at its bottom is inserted into a large pool filled with pure water. For the semipermeable membrane-solution system，the solution level will be about 22 meters higher than the pure water level. A double semipermeable membrane-solution system is structured by the pipe added another semipermeable membrane in the middle (such as 10 m from the bottom). Is there the level of pure water in the pipe higher than the level of the water in the pool? Thermodynamic analysis shows that which is not possible for the case of the equilibrium solution and will be possible for the uniform solution. But the latter case does not violate the second law of thermodynamics.