1905.] 



The Arc Spectrum of Scandium, etc. 



r>4i 



two appear to be lacking. Of the lines below intensity 6, the great 

 majority are missing from the Fraunhoferic spectrum. 



Scandium Lines and the Chromospheric Specjmm. 



The scandium lines which occur in the chromospheric spectrum, 

 though not so numerous as those in the solar spectrum, are of con- 

 siderably greater prominence. The strongest line of scandium at 

 A 4247*00 is very well developed in the chromosphere, and is, as far as 

 the metallic lines are concerned, inferior only to the lines of strontium 

 and calcium. Although all the scandium lines represented in the 

 chromosphere have high intensities in the scandium arc spectrum, 

 there are a few others of equal prominence in the metallic spectrum 

 which are either lacking or occur only as quite insignificant lines in the 

 chromospheric spectrum. 



Chromospheric Lines probably due either wholly or partially to 



Scandium. 



Scandium Lines in Sun-Spot Spectra. 



Between F and D, the region over which the Kensington observations 

 of sun-spot spectra extend, there are nine solar lines which have been 

 found to be due to scandium, either wholly or partially. Of these, five 



