| 摘要 |
PROBLEM TO BE SOLVED: To provide a method which easily achieves accurate measurement even relative to such a minute amount of a solvent insoluble matter that a quinoline insoluble matter is less than 0.01 mass%.SOLUTION: After a solution prepared by mixing coal tar with a solvent is supplied to a filter so as to be filtered, a lightness L in a filter medium of the filter is measured. The amount of a solvent insoluble matter corresponding to a measured value of the lightness L is obtained on the basis of a calibration curve indicating the relation between the lightness L and the coal tar whose solvent insoluble matter is known beforehand, so that the solvent insoluble matter in the coal tar is quantified. |
