ON WAVE-LENGTH TABLES OF THE SPECTKA OF THE ELEMENTS. 405 



Nitrogen (Vacudm Tube). 



Ames ('Phil. Mag.' xxx. p. 57, 1890). 



Eder and Valenta* (' Denkschr. Kais. Akad. Wissensch. Wien,' Bd. Ix. 1893). 



* Induction spark between moist carbons in air, which give also the following 

 ammonia bands: 2594-7, 2593-4, 2586'8, 2585-3, 2478-0, 2476-6, 2470-7, 2469-5. 

 f See Hasselberg's ' Positive Band Spectrum of Nitrogen,' Index, p. 213. 



This 'positive band' spectrum of nitrogen ('Index,' p. 112) consists of some 

 seventy or eighty 'bands,' each most intense at the least refracted edye, which 

 generally consists of three ' lines ' forming a ' head ' to the band. The measurements 

 of Ames are of the central line of the head. 



