Two methods are described for the approximate estimation of amino acids and other substances which may be separated on 1 and 2 dimensional paper chromatograms. The 1st procedure is based upon the observation that the area of the spot times its max. color density is proportional to the concn. of the material on the chromatogram. The 2d procedure is dependent on the observation that the concn. of a substance on a paper chromatogram is proportional to the max. color density of the spot as detd. by means of a photoelectric densitometer.