All ancient cultivators used furnaces made from six one mud for Dan refinement.
The recipe of six one mud was incomplete since a long time ago and the dispute over the exact content had been going on for over a century without any definite conclusion. Zhang Jintong was telling the truth—unless some forgotten treasure was discovered, this was the only divine furnace left in this world.
"The trace of a hut outside the cave was said to be left behind by our founder, but whether it is true or not I cannot say. The water from the waterfall can be used for Dan-refining, so feel free to use it. Oh, will you be staying here or going back to the temple with me?" asked the old priest.
"We'll be staying here. Thank you, Celestial Master," said Gu Yu.
"No problem. I will send people up with some necessities, today's dinner, and your luggage. I will visit you again tomorrow."
After that, Zhang Jintong leapt out of the cave promptly and descended the mountain without looking back. He knew the rules: Dan-refining was highly confidential and peeking was an offense punishable by death.
Celestial Master Temple still had some Dan-refining methods left, such as the pellets Zhang Shouyang gave Lu Yunqing earlier. But they were all made with ordinary Dan furnaces and the product was not even qualified to be given a grade. They were nothing but potent emergency pills or tonics.
This divine furnace, however, was something the current Celestial Master Temple had never used, for they did not even have the ability to activate it.
Right now, Gu Yu and Xiaozhai were circling around the Dan furnace. There was a solid and clumsy feeling about it. The outer layer was pitch-black as if it was covered in a thick layer of charcoal powder. For a moment there, they had no idea where they should start.
"How about we take it apart and rinse it first?" Gu Yu suggested all of a sudden.
"Sure. All yours. You're much stronger." Xiaozhai backed away for a couple of steps.
Gu Yu could not be bothered to retort. The hell with "stronger", you just did not want to get your hands dirty! Shaking his head, he rolled up his sleeves, grabbed the bead on the tip, used about a third of his strength, and twisted.
It did not budge.
He then used half of his strength and twisted it again. There was a "clunk" and the pagoda was loosened a little.
Gu Yu was utterly surprised. This time, he exerted all his force and "thud!" With a loud muffled noise, the pagoda top was finally removed. He looked down into the furnace and the first thing he saw was a huge strange container known as "water sea", which served as a cooling device.
Removing the water sea, there was the suspending cauldron, which was where the raw materials went; this part suspended in the furnace. Further down was the Dan stove where the fire was to be lit.
Breaking the furnace into four parts was a little tiring, but he acted as if he was exhausted. "I'm done. It's your turn."
"Tsk, tsk. You stingy man!" Xiaozhai gave him a scornful look and stretched out her right hand with the index and middle fingers pinched together. "Water, come!"
The words had just left her tongue when the milky way of a waterfall outside was cut short in the middle as if it had been broken into half by scissors. The lower part disappeared abruptly and it was two seconds later when the water resumed its downfall.
In front of Xiaozhai, however, a giant ball of water emerged out of nowhere.
As if it had life of its own, the ball of water slowly wrapped around the four parts and started squirming up and down, which was not unlike a mastrabating Green Slime.
Gu Yu found it kind of gross. "Why did you just do it silently? What's with the shouting?"
"Pretending I know Water-controlling Technique, obviously!" Xiaozhai replied matter-of-factly. Seeing that the transparent water ball was turning black, she pinched up her fingers again. "Go!"
The black ball disappeared right away. The next moment, it was out of the cave and splashed the mountain with a black shower.
Gu Yu would not respond to that, but turned to look at the parts. One look and he was astonished.
The treasure that had been covered in soot for a thousand years was finally showing its real charm. Once the charcoal was washed off, the furnace turned out to be of a mixed texture of metal, stone, and earth. The color was simple and uncomplicated.
"That's how a divine furnace should look. Sorry about what you had to put up with."
Gu Yu was delighted and carefully put the parts back. The big fellow now stood there as dignified as a mountain.
The sky had already gone dark after all this.
Four disciples of the Way of Celestial Masters swiftly ascended the mountain carrying all sorts of stuff. Zhang Jintong was very thorough. Among the supplies were tents, beddings, dishwares, a steamer, flashlight, a gaslamp, and wood charcoal for the fire—basically, everything.
Gu Yu and Xiaozhai set up their tent outside the cave and stopped their work for the day. They sat down and meditated with eyes closed so as to adjust their vital essence.
Be aware that the ancient cultivators would not begin to refine Dan until they had fasted, put on their headdresses and robe, and chanted their prayers to the heavenly masters. Only after all those would they go into the mountains at specific days, which had to be one of the auspicious dates in a mountain-opening month (the third or ninth month of the year). And they had to burn talismans before setting up their altars; the furnaces should also come with swords, ancient mirrors, etc.
Some were only there for a psychological effect, while some might actually help.
Gu Yu and Xiaozhai made no such deliberate preparations. It just happened to be March now and they picked an auspicious date, which was the following day.
The next morning, daybreak.
Gu Yu spent his whole night cultivating and had not stopped yet. He was breathing in and out the essence of early morning. Only when the morning sun had completely leapt out of the horizon, expelling the thin white mist in the mountain, did he stop his practice and rose to his feet. He could sense the abundant spiritual essence inside him.
Opposite him, Xiaozhai opened her eyes as well, which were also shining brightly, indicating the brilliance within.
Their eyes met and they kicked off the ground in unison, jumping into the cave.
Gu Yu opened the chest and took out a portion of the ingredients of Evil-dispelling Dan. It was lower in grade of the two and he thought they could use it for a trial run.
After years of experiments, Waidan techniques of Taoism had established a system of dozens of methods including flying, rising, drawing, subsiding, pointing, closing, nourishing, boiling, tempering, forging, grinding, sealing, etc.
Each one required a well-balanced coordination of the spiritual essence, mental force, skill, strength of fire, and other factors. The tiniest error could have a whole portion of materials go to waste.
According to the "Book on the State of Mind of Black Bead": to make the Evil-dispelling Dan, half of the ingredients was to be ground into small pieces first, then put inside small cloth pouches, each containing 100 g of the materials; the other half was to be dried in the shade before adding it into water and boiled. The pouches were to be suspended inside the cauldron and water was to be added frequently; the pouches would grow lighter in two to three days and the liquid in the furnace thicker; in four or five days, all the essence of the ingredients would dissolve in the liquid, which was when the pouches would be taken down and boiled; boil again until the water was dried up and the roughcast of the Dan was ready; collect.
As for when to feed the fire, the book said 300 g each at the hours of Mao and You, which meant 300 g of wood charcoal was to be added at 7.00 and 19.00 every day.
Could it at least try to be less sketchy? Apparently not! Their only option now was to start experimenting.
Gu Yu put the materials into the cauldron and hung the pouches, then closed the pagoda top. Xiaozhai added in the charcoal and started the fire. In a heartbeat, the interior of the furnace was red hot and the temperature was rising.
The couple then sat down cross-legged on either side and spread out their mental force, watching the furnace closely.
The materials consisted of various plants only, and once soaked, steamed, and boiled in the water, they soon melted into a mush; the water also turned into a strange mixed color of red, green, yellow, and black.
The dangling pouches were also saturated by the steam and became all soppy.
There seemed to be no end to the waiting. Fortunately, they could watch the furnace as they cultivated; the process was less boring that way. Zhang Jintong came once around noon, but dared not go in after seeing the wreathing smoke coming out of the cave. He left after standing briefly outside.
It went on like so. The couple added the charcoal and water as instructed and watched the furnace tentatively. Before they knew it, the day was over.
The pouches were indeed a little shrivelled. Gu Yu probed with his mental force and realized they were lighter in weight as well. The colors in the furnace had all fused together and were almost close to a shade of green.
It went on like this for the next four days.
The pouches had completely dried up and the "soup" was thicker than ever. Xiaozhai activated the Small Moving Technique, instantly taking out a pouch. She opened it up. Wow, the materials had almost all vaporized. All that was left were some dregs.
"We're almost there," said she.
"Ok, I'll go first."
Gu Yu reaches out and held the furnace between his arms. Two streaks of gentle spiritual essence flowed out of his palms and poured into the furnace through the two openings on either side of the stove. With this catalyst, the flame inside erupted a dozen centimetres upwards.
As the strength of the spiritual essence increased, so did the flame, which licked at the bottom of the cauldron as if it was going to devour and melt down the latter. The already thick liquid was bubbling noisily as bubbles formed and burst. It soon turned into a state halfway between solid and liquid.
This procedure was known as Dan-distillation, a prerequisite for the formation of Dan. There was also a corresponding procedure called Dan-degradation, which would be used when making complicated Dan.
Xiaozhai watched her boyfriend anxiously. It had been only less than twenty minutes and his face was covered in fine sweat. Even someone with spiritual essence as abundant as him could not afford to pour it out like so.
One slip of hand would cost them a fortune.
Another quarter of an hour and Gu Yu finally reached his limit. He shouted, "Your turn!"
It was not something Xiaozhai would take lightly; she immediately took over. As soon as Gu Yu removed his hands from the furnace, he found his gourd, gulped down some liquor, and lost no time in readjusting his breath.
Xiaozhai pursed her lips; the look on her face was more serious than ever. She was never as rich in spiritual essence and was draining up after fifteen minutes. It just so happened that the liquid was growing drier and smaller then and the roughcast was forming. Then, there came a "bang!"
A lump of greenish substance exploded and splashed all over the interior of the cauldron. It was a "miscarriage" (as in "they had lost control of the materials and everything had gone to waste").
"Sigh, that's on me!"
Xiaozhai heaved a sigh, noticeably disgruntled.
"Don't worry about it. That was only the first trial."
Gu Yu drank another mouthful of the liquor and said, "Dan-distillation is extremely energy-consuming. Next time, you go first. I can hold on longer than you and buy you some more time to readjust your breath."
With that, the couple reorganized themselves and began their second round of experiment.
The process began relatively easy; when it was time for Dan-distillation, Xiaozhai carried out the task first, followed by Gu Yu. This new strategy worked well. When Gu Yu was drained of his spiritual essence, Xiaozhai had just recovered hers to take over from him.
As she activated her spiritual essence, Xiaozhai reached into the cauldron with her mental force. The liquid had turned into a jelly-like substance and was of a deep green color. The lump now indeed looked like a Green Slime.
That was the roughcast in its most preliminary form. She immediately scooped it up with her mental force and wrapped it inside, then started kneading. The Dan would only take shape after the roughcast was round, even, translucent, and shiny.
Everything seemed to be going well, but a few seconds later, Xiaozhai's face darkened and she looked even more disgruntled than the last time.
As invincible and unparalleled as the Thunder Technique was in fighting enemies, its shortcomings were exposed in a major task like this one—she had not accumulated enough spiritual essence. The same thing happened again when they were so close to their success.
The roughcast failed to take form and was miscarried again.
She jumped to her feet, dashed out of the cave, and there came a series of clashing and rumbling sounds. A couple of minutes later when she had vented enough of her frustration, she came back in. "How far away were you?"
"I would have been able to take over in five more minutes." Gu Yu gave a rough estimation.
"The problem still lies in the recovery speed. I wonder if we can speed it up a little…"
Xiaozhai turned her head abruptly to look at her boyfriend, who smiled back at her warily. He took out a small case. In it were a few spiritual stones that were glowing dimly.
"As much as I could not bring myself to use them, it seems to be our only option."