A drop of potion-made acid does not die when it leaves the needle.
In the narrow approach hall between Entry hall 126 and Entry hall 128, the floor was a star-pattern of chemical scars. Qiao Ming’s lead line-weight had shattered the quartz pool of the Scholar’s metal pen. Then, twenty drops of ninety-eight percent burning acid had erupted outward in a fine, high-pressure mist. He splashed across forty paces of dark rock flat stone slabs.
Qiao Ming walked through the hall with his lantern held low, his bare feet stopping at the edge of the contaminated zone.
The sight was an offense to any water mapper who honored the stone.
Wherever the green acid had landed, the dark stone had turned a pale, sickly yellow. Small craters the size of coins were pitted into the rock, their margins covered in a frothing, yellow crust of iron sulfate and dissolved pink rock that continued to crackle and cry oily moisture in the damp draft.
If this residue were left upon the stone floor when the high tide arrived, the rising salt water would dissolve the sulfate crust. It carried packed acidic salts into the lower drainage drain tubes where it would attack the ancient lead joints and poison the freshwater reservoirs of Entry hall 101.
