196 



THE CHEMISTRY OF THE SUN. 



[CHAP. 



It is easily seen how each line almost can be differentiated 

 from all the rest. 



The lines in the yellow-green, the green, and two lines in the 

 blue, marked respectively in the diagram as a, b, c, and e, are 

 differentiated from the third line in the blue, d, by being seen 

 in the solar spectrum while d is not. The line in the yellow- 

 green and the least refrangible of the three blue lines are 

 distinguished from the b lines, and the most refrangible of the 

 blue lines by being invisible in the prominences. 



The middle line of the three blue ones (d) is differentiated 

 from the line in the yellow (a) by being seen in the Bunsen 

 flame while the yellow line is invisible. 



Sun. 



Flame of carbonic 

 oxide. 



Arc. 



Flame of cyanogen 

 led with oxygen. 



Bunsen. 



Spark. 



Prominences. 



FIG. 76. Showing the various intensities of the lines of Magnesium as seen 

 under different conditions. 



The I lines are separated from the others by being seen alone 

 when magnesium ribbon is burnt in a cyanogen flame fed with 

 oxygen, and the two less refrangible members of the b group 

 are differentiated from the third line by being seen alone when 

 magnesium ribbon is burnt in the flame of carbonic oxide. 



And, finally, the line in the yellow-green (a) is distinguished 

 from the least refrangible of the three blue lines (c) by being 

 seen strongly reversed in the sun, while the line in the blue is 

 only faintly reversed. 



