Densitometric Measurements of the K -α Line of Carbon

(BY CABLE.) DENSITOMETRIC measurements of the K- line of carbon in three orders obtained with a grating having twelve hundred lines. per millimetre show distinct, clearly measurable separation of components in the second and third orders, wave-lengths checking in different orders and on different plates. There are four principal components in the main line at 44.2 A., 42.0 A., 45.4 A., and 46.15 A. The relative intensities of the components apparently depend on conditions of excitation, some of the longer components becoming more prominent at higher driving potentials, thus explaining the divergence of wave-length values obtained by other observers in the third order. Some of these components apparently have a doublet structure.