X-ray L absorption edges and corresponding emission lines for elements Sb(51) to Sa(62).---The three $L$ absorption edges and certain adjacent emission lines of the same element were photographed for series of ten elements from antimony to samarium. Thus a direct measurement of the distances on the photographic plates from the $L{\ensuremath{\beta}}_{2}$ line to the ${L}_{\mathrm{III}}$ edge, from $L{\ensuremath{\gamma}}_{1}$ to ${L}_{\mathrm{II}}$, and from $L{\ensuremath{\gamma}}_{4}$ to ${L}_{I}$ made possible the determination of the ${N}_{\mathrm{IV}}$, ${N}_{V}$, and ${O}_{II\ensuremath{-}III}$ energy levels respectively. In certain cases the edge and line were obtained on separate plates having the same reference line. The method seems to be an advantageous one in cases in which the energy of the desired level is so small that a slight error in the wave-length of either absorption edge or emission line would make a considerable error when computations are based upon determinations of these by different investigators. Particulars are given concerning the making of absorbing screens containing free antimony, tellurium and iodine. With these screens the ${L}_{I}$ absorption edges for Sb(51), Te(52), and I(53) were found at 2631.7, 2503.9 and 2383.9 x-units; ${L}_{\mathrm{II}}$ edges at 2821.9, 2679.3 and 2547.5 x-units; and ${L}_{\mathrm{III}}$ edges at 2990.7, 2845.7 and 2713.9 x-units, respectively.Variation with atomic number of the values of the ${N}_{\mathrm{IV}}$, ${N}_{V}$ and ${O}_{II\ensuremath{-}III}$ energy levels.---The ${N}_{\mathrm{IV}}$ and ${N}_{V}$ levels, which form a relativity doublet, are very close together in the case of the lower elements studied and show a slightly greater separation for the higher elements. All the curves showing the variation of energy level with atomic number show a distinct bend at lanthanum (57) as is to be expected according to the existing theory, for the next element, cerium, marks the beginning of the rare earth group. The ${O}_{II\ensuremath{-}III}$ curve for antimony, tellurium and iodine runs nearly horizontal, and as this level represents the outermost occupied orbit in these elements, the values obtained should be related to the ionizing potential. The values so computed are of the proper relative order of magnitude but are somewhat lower than the values obtained by other methods. This would indicate that the beginning of the absorption edge represents transitions to optical orbits rather than to infinity.