Seven days later.
Yu Lie was in his rented stone house, where a bronze cauldron as tall as a man stood.
The cauldron was pitch black, and the roaring charcoal fire continuously licked its surface.
Yu Lie, bare-chested and with a serious expression, moved around the cauldron, constantly checking the heat.
He was refining pills, but these were neither Blood-Strengthening Pills nor Beast-Subduing Pills.
Instead, they were a special type of pill he had obtained from a miscellaneous shop after meeting Old Man Yu.
On a table far from the cauldron, a golden-red pill book lay open.
Each page bore the title "The Compendium of Lead, Mercury, and Flying Fire."
The pages were filled with repeated mentions of lead, mercury, saltpeter, sulfur, refined charcoal, sugar, and other ingredients, along with strange-looking tools imprinted on the pages.
This book was the one that had caught Yu Lie's eye in the shop.
It was a manual for making various types of gunpowder.
Gunpowder was a familiar substance to alchemists, especially the lowest-grade black powder, whose formula had been refined to the utmost simplicity.
When Yu Lie first started learning alchemy, he had considered starting with gunpowder.
However, gunpowder was categorized under the Metal and Stone Alchemy school, and it was highly dangerous.
Beyond the most basic formulas, more potent recipes were not accessible to novice alchemists.
To his surprise, Yu Lie had stumbled upon "The Compendium of Lead, Mercury, and Flying Fire" in the shop.
This book was renowned among alchemists.
It contained the "Secret of the Supreme Ancestor's Golden Elixir" by the alchemist Qing Xuzi, which included the earliest recorded formula for gunpowder in the Shanhai Realm.
The book detailed various methods for preparing gunpowder and provided blueprints for the most suitable firearms.
Its contents had remained unchanged for thousands of years.
Even a mortal, if brave enough, literate, and with sufficient materials, could create gunpowder weapons capable of killing a novice alchemist with copper tendons and iron bones or severely injuring an eighth-rank disciple.
Because of this, after numerous tragedies, the full contents of the book were restricted.
Only eighth-rank disciples were allowed to purchase and read it.
However, rules were one thing, and reality was another.
The book, being a classic, was still circulated among some novices and mortals.
Yu Lie's copy had been acquired by Old Man Yu from a novice alchemist.
It was an early edition from the Black Emperor's reign, not particularly rare, but still a three-thousand-year-old antique that could fetch a high price.
When Yu Lie expressed interest in the book, Old Man Yu, considering Yu Lie's background in alchemy, assumed he wanted to make gunpowder for self-defense.
He generously allowed Yu Lie to take the book home, reminding him of the dangers: "Gunpowder is dangerous. Black powder is one thing, but privately refining other types can be deadly. Even with your copper tendons and iron bones, you should be careful."
Old Man Yu also advised that the key to refining gunpowder was not just the formula and skill but the purity of the materials.
High-quality materials were hard to come by and expensive.
He suggested Yu Lie focus on other preparations and not spend too much time on the book.
Yu Lie agreed, promising to return the book in half a month.
Old Man Yu, not wanting to dampen Yu Lie's enthusiasm, sold him saltpeter and refined charcoal at cost price and offered to help him purchase more materials from the Alchemy Hall if needed.
Yu Lie was thrilled.
With his bronze wine cup, he could purify materials to a level even eighth-rank disciples found difficult.
The book had found the right owner and would soon be put to great use.
That day, Yu Lie was attempting to refine "Thorn Fireballs," a type of gunpowder that, when thrown, would explode and release dozens of sharp spikes, capable of killing wild boars or bears and stunning even a novice alchemist with copper tendons and iron bones for ten breaths.
As the fire roared under the cauldron, the lid trembled slightly.
Yu Lie, having been blown up multiple times in the past few days, instinctively prepared to jump away.
He had moved back to his rented stone house to avoid damaging the alchemy hall and its precious herbs.
The lid didn't fly off.
Yu Lie calmed himself and opened the cauldron.
Inside, he saw a yellowish, slightly orange powder.
He scraped some with his fingernail, sniffed it, and then tasted it.
A look of joy spread across his face.
"Thorn Fireballs, success!"
Excited, he almost slapped the cauldron in celebration but stopped himself just in time.
Gunpowder, especially anything stronger than black powder, was not to be trifled with.
He quickly removed the cauldron from the fire, scraped the orange gunpowder into a clay jar, and admired his work.
This jar alone could make a dozen or more Thorn Fireballs, each capable of killing a boar or bear.
At fifty to a hundred coins each, this batch was worth nearly a thousand coins, yet the cost was less than a hundred.
With practice, the cost would decrease further.
Moreover, Yu Lie's materials were purified by his bronze wine cup, making his gunpowder more potent than the average.
After storing the jar, Yu Lie returned to the table and flipped through the book again.
His eyes gleamed with excitement.
Thorn Fireballs were just the beginning.
There were other weapons like "Flying Sand and White Snow Fireballs," which burned fiercely and couldn't be extinguished by sand or water, forcing novices to scrape off their flesh to stop the fire.
There were also arrows like "Single Flying Divine Machine Arrows," "Rainstorm Pear Blossom Arrows," and "Miasma Poison Smoke Arrows."
But Yu Lie's ultimate goal was the "Divine Fire Crow," a weapon shaped like a crow, made of tin and iron, filled with refined gunpowder.
It had two gunpowder tubes on each side, connected to the gunpowder inside the crow.
When ignited, it could fly three hundred paces and explode like thunder upon landing, instantly killing mid-level novices and severely injuring higher-level ones.
Above the Divine Fire Crow was the "Fire Dragon Emerges from Water," a weapon that could fly even farther and explode underwater, capable of shattering mountains and rocks.
It was powerful enough to severely injure or even kill an eighth-rank disciple, equivalent to killing a seventh-rank monster.
It was on par with the paper talismans Yu Lie had used before.
Though difficult and dangerous to make, with strict controls on materials, Yu Lie was determined to acquire a few for emergencies.
With his mind set, he began planning where to obtain the necessary materials.
Friendly Recommendation: "I Am Immortal in the World of Strange Tales"