The "fire-mist" and the mephitic vapors were finally swept away; another era was preparing.

With inconceivable swiftness the mephitic vapors gathered.

No, graveyards were also "hot-beds of miasmata," sources of " mephitic vapors" widely believed to be extremely poisonous.

Mephitic vapors rise from its waters, so that no life is found on its banks, and no birds fly over it.