AbstractA method is described for the estimation of relative intensities of weak diagram lines from the microphotometer records of x‐ray emission spectra registered on photographic films. The method is based on first correlating the experimentally determined relative intensities of two intense diagram lines with the theoretically calculated relative intensities. The experimental relative intensities of weak diagram lines are then interpolated to yield the corrected experimental relative intensities. These interpolated experimental relative intensities are found to be in good agreement with the theoretical relative intensities. The method has been applied to some recently reported weak lines in the L‐emission spectra of the rare earth57La to6