PURPOSE: To obtain data equal to that of a square cell by eliminating birefringence by a method wherein a sample is dissolved directly in a cylindrical spectroscopic cell whose inside diameter is set at a specific multiple of the width of incident light, the sample is irradiated with visible rays or UV rays and a quantity of transmitted light is measured.

CONSTITUTION: As a material for a cylindrical cell, any material which transmits visible rays or ultraviolet rays such as a glass, a quartz glass, an organic glass, a plastic glass or the like may be used. It is desirable that the inside diameter of the cylindrical cell is set at six times or higher the width of incident light and that its thickness is set at about 1 to 5mm although it is not specified especially. A solvent is put into the cylindrical cell. A sample is fed directly, and it is then measured by such as photometric titration or the like after it has been stirred with a stirrer or the like and dissolved or while being stirred. As compared with a square cell, the cylindrical cell can measure the absorbance of a chemical liquid whose permeability is strong, it can follow up a high-speed reaction, and it can be adapted to the automation of an absorbance measurement.