Book 2: The Green Vapors: In the days of the Comet in 1906 is a science fiction novel by H. G. Wells 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 result The great Change has come for evermore, happiness and beauty are our atmosphere, there is peace on earth and good will to all men.