New Lines in the Ultraviolet Spectrum of Atomic Iodine

A total of 250 lines in the arc and first spark spectrum of atomic iodine have been photographed with a vacuum grating spectrograph. A grating of one meter radius and ruled with 30,000 lines per inch was used. The region covered extended from $\lambda 1900\mathrm{A}$ to $\lambda 800\mathrm{A}$. The spectrum was produced in a mixture of argon and iodine. In part of the work, iodine was prevented from entering the spectrograph by a continual flow of pure argon from the spectrograph through the slit to the discharge tube. This permitted the extension of wave-length measurements below the fluorite region to $\lambda 800\mathrm{A}$.