SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 95, NO. 2, PL. 



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An al^al .spectroKraiii, obtained by exposing plate 42 of ChlorcUa vulqaris to 

 ultraviolet rays for ( i ) 64 minutes. (2) 16 minutes, and (3) 2,^ minutes, .super- 

 miposed on a diagram of the intensities of the wave lengths. 



The abscissae are wave lengths in angstroms: the ordinates are intensities 

 m thousands of ergs 'secern'. 



