Ghost Marriage: The Bewitching Corpse

Chen Chen looked, and sure enough, Zhu Liu's entire face had turned pitch-black, like a rotten persimmon, horribly repulsive. He couldn't help frowning.

Second Uncle continued, "In my opinion, this poisonous gas must be mercury vapor."

Chen Chen was startled. "You mean gas formed from quicksilver?"

"That's right. Mercury is poisonous in its own right, and it becomes even more toxic as a gas. The mercury vapor coming out of a corpse's mouth is especially dangerous, because it also carries corpse miasma. The two poisons combined are what corroded his face into this state."