The convex side of a curved crystal will diffract a continuous range of x‐ray wavelengths simultaneously. Thus, it is useful for spectral analysis of flash x‐ray tubes or plasmas where there is not sufficient time to scan through the spectrum with a spectrometer. It is also convenient for detecting impurities in x‐ray targets and could be used for x‐ray spectrochemical analysis. The choice of analyzing crystal, the particular diffracting planes, and the orientation of the bending axis allows a considerable versatility in intensity and dispersion including the recording of two or three separate spectra in a single exposure.