The air didn’t cool down. It died.
At a depth of three miles below the mortal crust, the air pressure climbed to four sea-weights. Every breath felt like sucking wet silt through a coarse wool blanket. The surrounding heat plummeted through zero, through minus twenty, down into a dead, unnatural minus forty-five degrees.
Lin Ke swung slowly in the iron harness, the cold-forged winch cable creaking above his head like an over-tuned fiddle string.
Below him, the darkness was not empty. It was filled with a swirling, thick, sticky Stygian fog that possessed the distinct chemical tang of packed strong etching acid and ozone.
As a test, Zhao Wuji had hung a common iron horse-nail from his tool belt.
Lin Ke watched the nail closely. Within ninety seconds of entering the fog, the bright grey steel had turned a mottled, blistered orange. Ten seconds later, the head of the nail flaked off into rust powder. It dissolved into the freezing draft before the iron hit the stone walls of the shaft.
“Acid-burning vapor,” Zhao Wuji whispered through his fur-lined breathing mask, his teeth chattering wildly. “It’s eating the metal.”
“Worse than that,” Lin Ke said, his voice muffled by the thick scarf wrapped around his face. “It triggers acute living vasospasms. The cold is pulling heat out of our tissues faster than blood can circulate.”
