10 



PROCEEDINGS OF THE AMEBK AN ACADEMY. 



tin- lluorescence spectra makes this result necessary as far as that 

 method of excitation is concerned. Th* fluorescent* spectrum qf a crys- 

 tal ofjluoriU is a function qftht exciting soura , <t/i>/ changes compL U ly 

 when tin exciting wan lengths are changed* It is therefore improbable 

 that anyone of the flnorescenoe spectra should show more than approx- 

 imate or accidental coincidences with many lines excited by either heat 

 or kathode luminescence. Then; arc lines which appear in the flnores- 

 cenoe spectra of a crystal under excitation by several different scare 



i \i;i.i: v. 

 Purple W'i a.rd u.i (Eng Flu< iri i i 



Hem 



hand. 



Wave 



5669 



5 7 5 1 



5780 



it) 



■ to 



' 5857 



i 5871 



to 



( 5908 



6045 



0111 



max. 



Intensity. Bemarka, 

 10 ratherdif. 

 max. in band. 

 1 max. of band. 



band. 



rather weak band. 



5 



1 



