AbstractThe usefulness of the analysing crystal is generally governed by its angular dispersion and reflecting power. This is particularly so today where the increasing requirement for more speed and greater accuracy can often only be obtained by the availability of higher net intensities. Although the performance of the conventional X‐ray spectrometer is satisfactory in the middle portion of the wavelength range, it lacks dispersion at the short wavelength end and sensitivity at the long wavelength end. For this reason, there is a continuing search for crystals which offer more angular dispersion in the 0.2 to 2 Å range and better reflecting power in the 5 to 20 Å region.This paper discusses results obtained with some of the newer analysing crystals which have become available during the past couple of years. These crystals include pyrolitic graphite, rubidium acid phthalate, sorbitol hexa‐acetate, and the (420) and the (422) cuts of lithium flu