The Preparation and Properties of Auroral Afterglows

The preparation of auroral afterglows in pure nitrogen is discussed in detail. A nomenclature is introduced for the five stages which are met most frequently in the preparation of these glows. In the normal order in which they occur they are the ozone, nitric oxide, cyanogen, Lewis-Rayleigh, and finally the auroral stage. Two plates, one showing the spectrum of the discharge in pure nitrogen, which is responsible for the production of the auroral glow, and one which shows the spectra of the nitric oxide, cyanogen and auroral stages, are reproduced.