What We Learn from the Sun 



through absorbent vapours gives a rainbow- 

 tinted spectrum crossed by dark lines, these dark 

 lines having the same position as the bright lines 

 belonging to the spectra of the vapours; so that, 

 from the arrangement of the dark lines in such 

 a spectrum, one can tell the nature of the vapour 

 or vapours which surround the source of light. 

 The application of the new method of research 

 to the study of the solar spectrum quickly led to 

 a number of most interesting discoveries. It 

 was found that besides sodium the sun's atmos- 

 phere contains the vapours of iron, calcium, 

 magnesium, chromium and other metals. The 

 dark lines corresponding to these elements appear 

 unmistakably in the solar spectrum. There are 

 other metals such as copper and zinc which 

 seem to exist in the sun, though some of the 

 corresponding dark lines have not yet been 

 recognized. As yet it has not been proved that 

 gold, silver, mercury, tin, lead, arsenic, antimony, 

 or aluminum exist in the sun though we can 

 by no means conclude, nor indeed is it at all 

 probable, that they are absent from his sub- 

 stance.* The dark lines belonging to hydrogen 

 are very well marked indeed in the solar spec- 

 trum, and, as we shall see presently, the study 

 of these lines has afforded most interesting 

 information respecting the physical constitution 

 of the sun. 



* Helium was detected as an element in the solar spec- 

 trum in 1868; in 1895 it was discovered as a terrestrial ele- 

 ment in the gas liberated from cleveite and some other rare 

 minerals. Ed. 



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