The Ultraviolet Absorption of Methane

THE absorption spectrum of methane in the Schumann region was photographed first by Leifson(1) using a small vacuum grating spectrograph and an uncondensed discharge in hydrogen as a continuous source. He found six bands at low pressures all below 1558A. Rose, 2 using the same source and a small prism instrument, was unable to find these bands, and suggested that Leifson's bands were merely gaps in the band spectrum of hydrogen, which appears with great intensity in such a source. The object of the present work was to photograph the spectrum under greater dispersion and resolving power, using a source which gave a true continuum in the region in question and to extend the spectrum to shorter wave-lengths, below the Schumann region.