a novel method of separating a particular component from its liquid solution by the use of a vessel divided into a solution chamber receiving the liquid solution and a vacuum chamber by a permeable membrane having selective permeability . the method is characterized to evacuate the vacuum chamber while keeping the liquid solution out of direct contact with the permeable membrane such that the permeation of the particular component through the permeable membrane can be effected in vapor - to - vapor phase environment , which is found to give a superior separation result for the liquid solution .