Without bread, a man may endure for three weeks. Without salt, his mind shatters and his blood curdles within seven days.
In the vast residential arcades of the Eighty Courtyards, salt was the invisible keystone of survival. It was needed to cure the thousands of tons of sea-kelp and dried fish salvaged from the arks, to pickle the tender watercress sprouting in the fiery tufa beds, and to maintain the electrolyte balance of ten million human bodies living in unending underground warmth.
The sea outside held infinite salt, but it was raw, bitter deep-sea salt water. Soaked with toxic magnesium salts, chalky calcium sulfate, and the skin-burning spirit-waste scum spewed by dying sect flagships. To drink it was madness. To boil it clumsily over wood fires produced only a bitter, poisonous crust that caused violent stomach cramps and kidney failure.
On the ninth morning, Qiao Ming led forty master salt-boilers from the coastal guilds down into Entry hall 040: the Industrial Boiling Sumps. Here, three hundred paces below the residential courtyards, the stonework was raw, huge, and functional. The floor was formed of massive six-sided slabs of dark fiery dark rock, resting directly upon the heat-exchangers of the sub-keel fiery chimneys.
