Classification of the Arc Spectra of Nitrogen and Carbon

Infra-red work.---A carbon arc in air run at 125 amperes served to produce the arc spectra of carbon and nitrogen with great intensity. Using an infra-red spectrometer with a plane grating and a vacuum thermopile the wave-lenths and approximate intensities of about one hundred and twenty-five lines between 9000A and 20000A have been measured. About ninety of these lines are classified as combinations between terms in carbon I and in nitrogen I. A number of new terms are fixed in both of these spectra and many of the terms provisionally identified by Fowler and Selwyn in C I and by Compton and Boyce in N I are definitely confirmed.Classification in the visible spectrum of nitrogen I.---Using data obtained by Duffendack and Wolfe a number of lines have been classified in the visible spectrum of nitrogen I. Reasons are given for changing the previous designations of the ²P and ²D terms found by Kiess at 5100 and 6800 respectively. These are assigned to the 2s²2p²·3p configuration and are considered as being based on the ¹D term of nitrogen II. A complete term table of nitrogen I is given.