240 



THE CHEMISTRY OF THE SUN. 3 [CHAP. 



produced in furnace D would not be the same as th% strongest line 

 produced in furnace A; so that in that way we can imagine a 

 very high temperature giving a very strong line in the spectrum 

 of a particular substance, which may yet at a lower temperature 

 only appear as an exceedingly feeble one. 



Evidence furnished ly Calcium, Magnesium, and Lithium. 

 This being premised, let us now go back to page 194, and 

 study what was there said regarding the variation of spectral 



Fia. 88. The varying intensities of the lines of Calcium as seen under different 



conditions. 



FIG. 89. The varying intensities of the lines of Calcium with increasing 

 temperatures. 



lines from this new point of view. I there gave the facts touch- 

 ing the variations in the spectra of calcium, magnesium, and 



