H. G. Wells 
In the Days of the Comet [EPUB ebook] 

This book tells the story in which humanity is "exalted" when a comet causes the nitrogen of the air, the old azote, to change out of itself and become a respirable gas, differing indeed from oxygen, but helping and sustaining its action, a bath of strength and healing for nerve and brain.
The incident resulted in happiness, peace on earth and good will to all men.