"What are you all doing here?"
At the sound of the voice, Jin and the others turned toward the entrance to see Saki standing there.
"Saki!"
"Where have you been? I've been worried sick!" Toa exclaimed, rushing toward her. Although Laojun had been tracking Saki’s location from Hourai Island and had confirmed she was safe, a parent's concern was not so easily dismissed.
"I'm sorry, Father," Saki said, bowing her head as Toa ruffled her hair with rough affection.
"Well... fine. At least you're back in one piece. But you could have at least sent word, couldn't you?"
Aaru was currently equipped with a manacam, but unless Saki gave the order, the automaton would never use it of her own volition—even if she was reporting to Laojun.
"Yeah... I'm sorry."
"It's not like I have much room to talk, since I'm always wandering about myself," Toa admitted. "But stop making your 'family' worry like that."
"Okay... I will."
Physical safety was one thing, but her state of mind had been a mystery. That was why Toa urged her not to suffer alone and to talk to him instead. Finally, he added one more thing.
"If you're truly against it, I won't marry Lina."
"Father!" Saki was the first to object. "You can't do that! You raised me all by yourself without a mother... well, to be honest, I spent a third of the time at Grandfather's and another third with the maid... but still, you have a life of your own, too!"
"Saki..."
"So, Father, I want you to think about your own happiness. Isn't a family's happiness your own as well? If not, then you're not really a family. Isn't that right?"
"...Thank you."
Toa pulled Saki into a gentle hug, and she softly returned the embrace.
"Ahem... cough."
Seeing that the matter had been settled peacefully, Reinhard gave a pointed, feigned cough. Startled, Saki and Toa hurriedly pulled apart.
"It's wonderful to see such a close bond between father and daughter," Reinhard said with a smile. "Now then, Saki, what did you bring us?"
He looked toward the box held by Aaru, who was waiting behind her mistress.
"Oh, right! Listen to this..."
Saki began to explain her findings. She skipped the part about her drunken misadventures and focused on the geological survey she had conducted near the town of Torom on the southern shore of Lake Tosmo.
"These are the ore samples."
Aaru opened the box, revealing opals and...
"...Dirt?"
At a glance, the mineral looked like nothing more than common soil.
"Wait a minute. This is... Analyze! Just as I thought!" Jin cried out.
"Heh, I knew you'd recognize it, Jin."
"Yeah. This is... bauxite."
Bauxite was famous as the primary source of aluminum, though it wasn't a single mineral. Rather, it was a mixture of several minerals, like gibbsite. Being an engineer rather than a scholar, Jin used the term bauxite out of habit, just as professionals in the metal industry did back on Earth.
Its main components were aluminum oxide and aluminum hydroxide.
"For some reason, aluminum is rare in this world," Jin mused.
Compared to Earth, aluminum was scarce. Instead, titanium was the metal harvested in abundance and referred to as light silver—ironic, considering aluminum was the metal called light silver in Earth's history.
"But wait... across Lake Tosmo...!"
Jin suddenly remembered a use for aluminum that didn't involve the metal itself.
"Alumina!"
"Alumina?"
Everyone else in the room tilted their heads in confusion.
"Ah, right. Alumina is a material made from bauxite, and it has incredible heat resistance."
With a melting point of 2,072 degrees Celsius and the chemical formula Al2O3, Jin realized he could use this as the material for the furnace. Since it could be sourced from the opposite shore of Lake Tosmo, it would save both time and money.
Jin explained his plan to Reinhard, who immediately began making arrangements to acquire the bauxite.
The region including the town of Torom was under the direct control of the Imperial family. Normally, obtaining permission to develop such land would be a bureaucratic nightmare, but the name of the Magi Craft Meister, Lord Jin Nidou, carried immense weight.
Despite having only just returned from a tour, the Empress prioritized the request and processed the paperwork personally. The permit was granted the very next day.
Trial mining began on October 16th. The primary concern was to avoid disturbing the local fishing grounds.
"Grand Search... Yeah, it's fine. We don't need to dig toward the lake; there's a substantial deposit further inland."
Jin had come to the site to inspect the underground conditions and relayed his findings to the site foreman. The Grand Search spell was a basic earth attribute magic, but like Analyze, it required the caster to have a clear understanding of the target material to recognize it. The earth attribute magi in charge of construction couldn't have identified the bauxite deposits with only the samples Saki had provided.
"Dig."
Jin carved out a pilot tunnel to serve as a guide for the excavation and secured enough bauxite for a prototype furnace at the same time.
"This should give you a general direction to follow."
"Oh, thank you very much, Lord Jin Nidou!" the site foreman replied gratefully. The site immediately bustled with renewed energy.
"When handling bauxite by hand, please ensure everyone wears a mask—something to cover the nose and mouth—so they don't inhale the dust. If possible, let the golems handle the actual work."
Remembering that inhaling bauxite dust could lead to pneumoconiosis, Jin gave strict safety instructions. He spent the rest of the day at the site monitoring the progress. Seeing that things were proceeding smoothly, he left the rest to the site foreman and returned to Kalts Village.
Finally, the trial production of the desiccant plant began. They separated the alumina from the bauxite and used Fusion to solidify it into the shape of a furnace. For the prototype, they kept it relatively small—just enough to produce about 40 kilograms of quicklime per batch.
"I'll install a Heat magi tool at the base."
"I see. That will provide the internal heat for the furnace," Reinhard said, having already memorized the blueprints.
"Exactly. Alumina has good thermal conductivity, so the heat will spread through the interior quickly, reaching about 1,100 degrees."
For a temperature monitor that could be easily replicated, Jin decided to use copper. Copper has a melting point of 1,083 degrees Celsius. By placing a small piece of copper in a pocket built into the furnace, they would know they had reached approximately 1,083 degrees when it melted. Since the interior of the furnace would be slightly hotter than the monitoring pocket, it was a perfect gauge.
"Alright, trial run."
Over the two days it took to get the bauxite, they had also gathered a sufficient supply of limestone. They loaded about 30 kilograms into the furnace, sealed the lid, and activated the magic.
"Heat."
They maintained the temperature until the copper monitor melted, then stopped the magic one minute later. After that, they had to wait for the furnace to cool.
"...Man, this takes forever."
Because the alumina furnace had such high heat retention, it cooled down very slowly. In the end, they weren't even able to open the lid that same day.
"Magic really is a convenient thing, isn't it?" Toa muttered wistfully as he glanced at the furnace, which was still radiating heat.
"Father is right," Saki added. "If we're going to do it this way, we need a design that lets us take the finished quicklime out so it can cool outside the furnace."
"I agree," Reinhard said, thinking of the logistical side. "That way, we can load new material and start reheating while the furnace is still hot. It would be much more efficient."
"True. In that case, the structure should be..." Jin murmured, falling into thought.
"What if we made it a long tube?" Elsa suggested. "Put materials in one side, heat them, and pull the quicklime out the other. Like a continuous flow?"
"Hmm, if both ends are open, I'm afraid too much heat will escape," Toa pointed out.
"Oh, right..."
"Then how about making the furnace so it can rotate? We could tip the contents out easily," Saki suggested.
"If we do that, the monitoring copper will fall out or get mixed in..."
"What if we tried a double-walled design..."
Ideas were traded back and forth until the basic design of the furnace was finalized. This was the beginning of the technological revolution for the common people that Toa had championed.
By October 19th, two days later, they had completed an improved rotary furnace. That very day, they produced 200 kilograms of quicklime.
The quicklime was packed into double-layered hemp bags, five kilograms each. The bags were labeled: Keep Dry. Warning: Heat and Fire Hazard.
"The prototype is a success."
The stock would likely be stored in a sealed warehouse for management.
"Let's set the price at 500 Toll per bag," Toa suggested. "That's about 100 Toll per kilogram."
The price was set. All that remained was to see if the people would buy it.