After the discovery by Vegard of the luminescence which occured in solid nitrogen under cathode ray bombardment at the temperature of liquid hydrogen considerable interest was attached to it on account of his attempt to explain the well-known auroral green line as due to this luminescence under certain conditions in the upper atmosphere. His theory of the auroral line was not corroborated by the experiments of McLennan and others, who showed that the line was due to oxygen. But the luminescence in solid nitrogen retained a very considerable interest as an outstanding example of the phenomenon of luminescence. From this point of view its spectrum and its properties were further studied in this laboratory where there were available all the necessary facilities for low temperature research. The investigation was commenced by McLennan, Ireton and Thomson, and the present research was a continuation of their work. Its object was to photograph the spectrum more completely, and to obtain further data in connection with the luminescence which might lead to an adequate explanation of the phenomena observed. Apparatus for Producing the Luminescence . The apparatus for producing the luminescence was with some few improvements in detail, the same as that described by McLennan, Ireton and Thomson. Use was made of a type of cathode ray tube designed by Dr. Coolidge, of the General Electric Company. With such a tube it was possible to obtain high velocity cathode rays outside the generating tube. The essential details of the apparatus are shown in fig. 1.