ON -W^AVE-LENGTH TABLES OF THE SPECTRA OF THE ELEMENTS. 195 



Potassium — contimied. 



L. de B. = Lecoq de Boisbaudran. 



f L. & D. = Liveing and Dewar. 



Rubidium. 



Kayser and Runge (' Ueber die Spectren der Elemente,' Pt. III. 5. Berlin, 1890). 



o 2 



