Purification of the 3, 5-xylenol+2, 5-xylenol and the 2, 5-xylenol+naphthalene systems was attempted by normal freezing. They are simple eutectic-forming organic mixtures. Experimental conditions such as lowering rate of sample, diameter of a glass tube, temperature of cooling section, and stirring rate of liquid sample were examined. The experimental results showed that a good separation was achieved under the conditions of sufficiently small lowering rates with sufficient stirring of the liquid sample. The difference of the diameter of the glass tube and temperature of cooling section did not affect on separation efficiency. When xylenol was a main component, the crystal grew like dendrite. On the other hand, the crystal grew like grain when naphthalene was a main component. Best separation was observed for the system in which 2, 5-xylenol was a main component and naphthalene was contained as an impurity component. Furthermore, concentration profiles for impurity in the solid were correlated by a model of trapping of mother liquid with the effect of adsorption of impurity on solid surface.
