The L-Series in the Tungsten X-Ray Spectrum

X-ray Spectrum, L-series; Wave-lengths.—Dershem's results were verified, for the most part within 1/10 per cent., except in the case of 1.777 × ${10}^{-8\mathrm{}}$ cm. which was found to have a wave-length of 1.202 × ${10}^{-8\mathrm{}}$ cm. Six new lines were discovered, four of which may belong to tungsten: 1.236, 1.213, 1.079 and 0.793 × ${10}^{-8\mathrm{}}$ cm. This last line appeared light in contrast to the dark bromine absorption band in which it was located; an explanation of this fact is suggested. Dershem's method was used with a very thin crystal and with very long exposures of the Coolidge tube. Four photographs are reproduced.