Chapter 104: Sulfur Purification

After more than a month, the three hundred or so people following Chu Yun had transformed into a well-trained force. Commoners followed the orders of their minor squad leaders, who in turn answered to middle-ranking leaders, who reported to the high-ranking leaders, all of whom ultimately took orders from Chu Yun. From top to bottom, no one dared to question him anymore.

Whatever Chu Yun commanded, they did. When he ordered them to change course and settle in a desolate, uninhabited mountain range, they immediately pitched tents. When he then ordered them to excavate the barren hills, they set to work without hesitation.

Although civilization was primitive here, sulfur was already known in the region. For instance, Yang Hong had used sulfur water to wash his body to kill lice. Naturally, they recognized the substance and knew it was valuable. When they unearthed the sulfur-rich ore, they were filled with astonishment and could not help but exclaim in wonder.

"I honestly didn't understand why the Count wanted us to dig in these barren hills, which were barely covered in weeds and smelled foul. I never imagined there would be sulfur in this soil!"

"With so much sulfur, we’re going to be rich!"

"The Count is truly a divine being to be able to see that there was sulfur beneath this earth!"

Their faith in Chu Yun grew even stronger. When he instructed them to keep the secret of the sulfur mine, they all swore they would never let word leak out. Under Chu Yun’s direction, the group spent six days digging, piling the ore into a small mountain.

After lunch that day, while the others were resting, Chu Yun had Huang Daniu assist him in using a jar to amplify his voice. "From now on, we will pause the excavation and begin purifying the sulfur from the ore. The method is quite simple, and I will demonstrate it for you now."

With that, he had a large bronze cauldron cleaned and filled with sulfurous ore and a generous amount of water fetched from a tributary of the Nanhai River. He then produced a lid he had specifically commissioned from the craftsmen over the past few days.

The lid was fashioned from bamboo and featured a circular hole in the center. Chu Yun inserted a hollowed-out bamboo pipe into the hole. After placing several heavy stones on the lid to seal it, he connected another curved bamboo segment that led three or four meters away from the cauldron. Finally, he connected this to a sealed wooden barrel topped with burlap, which was then submerged in a basin of cold water.

Having constructed this makeshift distillation apparatus, he ordered a fire to be lit beneath the cauldron. As the water boiled, the steam traveled through the bamboo pipe into the wooden barrel. Because the entire system was sealed, with the only ventilation provided by the barrel in the cooling unit, the temperature could reach the 115 degrees Celsius required for sulfur purification. The steam inside the bamboo was, in essence, a mixture of sulfur and water vapor. As it flowed into the barrel, the cold water cooled it, turning it into sulfurous water.

"Do not place too many stones on the lid," Chu Yun cautioned. "Thirty catties—half a dan—is sufficient. If you add more, the bamboo will not withstand the pressure of the steam, and there is a danger of explosion. You must remember this. Do you understand?"

Aware of the risk, Chu Yun repeated the warning four or five times to ensure no one would overload the lid. Hearing the word "explosion" and sensing the danger, the men listened with intense focus.

"Also," Chu Yun added, "keep an eye on the cold water in the basin. If it warms up, replace it immediately. However, do not waste the hot water from the basin; you may use it to bathe."

Pointing to the burlap on the barrel, he continued, "Lastly, be very careful. Once the water in the bronze cauldron boils dry, you must stop. You can tell if it has boiled dry by watching the burlap; if no more steam escapes, the water is gone."

"The three high-ranking leaders must ensure the safety and efficiency of their respective teams. This afternoon is for practice and familiarization. Starting tomorrow, whichever team produces the most high-quality sulfur will be rewarded with three copper coins per person."

Previously, the reward had been only one or two coins. The prospect of three coins per person stirred great excitement among the men.

Once the water in the cauldron had boiled away, Chu Yun had the fire extinguished. "After the water is gone, remove the barrel and dry it by the fire or in the sun. Once the steam has evaporated, what remains inside will be pure sulfur crystals."

Chu Wencai, watching the process, could not help but ask, "Count, I know you possess divine wisdom and that all your methods are correct. I shouldn't question you, but I am confused. If we dry the barrel to evaporate the water, won't the sulfur evaporate along with it? After all, you said we were using steam to obtain pure sulfur, didn't you?"

Chu Yun smiled. "The steam entering the barrel is from boiling water and is extremely hot, which allows the sulfur to remain suspended in it. When we dry it later, the temperature will not be nearly as high, so the sulfur will not evaporate."