The sulfuric stench in the deep cellar of Furnace Seven was thick enough to curdle milk.
Lin Ke crouched before a shallow heat-proof trough, stirring a bubbling, greenish-black slurry with a long iron rod. His right palm throbbed with a dull ache under its calloused scar tissue. But his left hand held the rod steady, moving in rhythmic, counter-clockwise circles.
Beside him, stripped to the waist and drenched in sweat, Meng Shan was shoveling crushed limestone powder into the trough.
“Sixty carts,” Meng Shan rumbled, resting his shovel against a mountainous pile of black, glassy rubble. “All taken from the disused tailings dump behind the south blast walls. The overseers thought we were hauling waste to fill the road ruts.”
“To them, it’s waste,” Lin Ke said, without breaking his stirring rhythm. “To a traditional smelter, high sulfur and quartz dust content means cold-shortness—iron that shatters like dry fine china when struck by a hammer. So they throw it away.”
Lin Ke pulled the iron rod from the slurry.
A thick, dark crust adhered to the metal, glistening with faint, rainbow-bright violet veins under the lantern light.
* * *
Ordinary smelting was a brute-force heat operation: burn coal, melt rock, pour metal. When dirt invaded the melt, fighters had no concept of chemical fluxing. They simply dumped the entire heat into the melted rock waste ditch and cursed the fire gods.
Lin Ke looked at the slurry through his internal test lens.
“Meng Shan,” Lin Ke instructed softly. “Second phase. Engage Shard Two.”
Meng Shan nodded.
The giant knelt beside the iron trough, placing both massive palms against the cold cast-iron casing. His breathing dropped into the slow, underground rhythm of the Distributed Earth-Core Stance.
His skin turned a deep, matte dark rock-grey.
Instead of forcing volatile spiritual energy into the melt, Meng Shan channeled a steady, low-hum sound shaking straight through the metal casing into the liquid. It was a gentle, ringing pulse that mimicked the deep earth-shaking deep ring of solid bedrock.
The greenish-black slurry began to churn.
Under Meng Shan’s high-pitched earth shaking, the crushed limestone powder reacted furiously with the molten sulfur. It formed calcium sulfide scum that rose to the surface like curdled foam.
Lin Ke skimmed the toxic yellow scum off with an iron skimmer, dumping it into a sandbox of wet lime.
Then, Lin Ke connected a flexible copper intake hose to the main exhaust line of the active fire above, routing a stream of pure carbon monoxide gas directly through the bubbling core of the iron.
The chemical reduction was total.
The carbon monoxide stripped the oxygen molecules from the iron oxide. Meanwhile, the high magnetic field generated by the ringing dark rock shaking lined up the metal crystals into a dense, linked lattice.
Four days and four sleepless nights passed in the cellar.
They didn’t stop for meals. They chewed hard sorghum biscuits and drank cold tea steeped with Apothecary He’s bitter willow bark. Lin Ke’s eyes were bloodshot, his glassy glass channels humming with constant, low-grade test load. But his hands never wavered.
By dawn on the fifth day, the cellar went quiet.
* * *
On the stone floor lay eight box-shaped wooden crates, packed with cooling sand.
Lin Ke grabbed an iron clamp, reached into the center of the first crate. Then he lifted an eight-pound metal bar into the morning light filtering through the high grate.
The metal bar was not dull grey like standard pig iron.
It was a deep, lustrous midnight-blue. It shone with a cold, metal mirror sheen that seemed to draw the surrounding light into its core. Lin Ke brought his iron metal pen within four inches of the metal bar. Then, the needle leaped from his fingers. It snapped against the blue metal with a sharp, ringing CLACK.
Cold-Forged Magnetic Iron.
Ultra-pure. High magnetic permeability. Zero sulfur embrittlement.
To an ordinary blacksmith, it was decorative ore. To an array master or a flying-sword artisan, it was liquid gold. The essential foundational substrate needed to anchor high-hum flight matrices and magnetic floating runes.
Standard spirit iron sold for twelve copper chits a pound.
Cold-Forged Magnetic Iron sold for sixty low-grade spirit stones per bar.
“Eight hundred pounds,” Meng Shan murmured. His heavy eyes reflected the midnight-blue sheen of the stacked metal. “That’s... Forty bars.”
“Two thousand four hundred spirit stones in pure material value,” Lin Ke said, his voice flat and steady. “Sourced entirely from discarded melted rock waste.”
The cellar door creaked open.
Shen Yue slipped down the wooden stairs, her apprentice robes tucked tight against her belt. She carried a bundle of yellow paper strips inscribed with dampening runes.
Without speaking, she knelt beside the crates and began applying the dampening magic charms to the cedar wood. Each magic charm locked into place. Then, the intense magnetic field and lustrous blue soft glow of the metal bars collapsed into the dull, unremarkable appearance of common paving ballast.
“The guild checkpoints are active on the main road,” Shen Yue whispered. She wiped a smudge of red stone from her cheek. “Steward Qian’s guards are stopping every cart leaving the Seventh Ward, searching for unmanifested spirit iron.”
Lin Ke stepped toward the handcart in the corner, throwing a heavy hemp tarp over the muffled crates.
“Then we don’t take the main road,” Lin Ke said, securing the lashings with double clove hitches. “We go to the Free Students’ Bazaar.”