When an alchemist doesn't use his spiritual energy to purify an ingredient and instead directly uses fire to burn it, they successfully kill impurities present in its outer surface but not those present deeper inside it.
The leftover impurities seep into the deepest part of an ingredient, where lies its medicinal essence.
What happens then?
The impurities become one with the medicinal essence and corrupt its purity.
When a person uses such medicinal essence to refine a pill, what he creates carries toxins within it.
If a person eats such pills in large quantities, the toxins build up inside them, and when it reaches an amount their body can not endure, they fall ill, sick, and even worse, find their cultivation base dangling on the verge of destruction.
People who use an enormous amount of pills to advance their level usually find their elixir field breaking down or their spiritual core shattering when the toxins they have suppressed in their body erupts.
The fact that pills in the market carried harmful substances was the main reason why the alchemist association of the present had put a limit on the consumption of pills.
Some pills, a person could only eat one or two.
Different pills had different consumption limits.
The method Xie Yang used targets the impurities present in deeper parts of the ingredients and expels them.
The black and yellowish dots that Xie Ye saw was such impurities.
As Xie Yang had expelled most impurities that lay deeper inside the ingredients, he did not need to worry too much about the amount of toxins that might mix with the medicinal essence of the ingredients when the fire cooks them because the amount would be so minuscule that a cultivator's immune system would suppress it and eventually expel it out of the body through the pores.
Xie Yang started the second step of refining pills by heating the cauldron.
The cauldron had three magic runes on it, and Xie Yang channeled his spiritual energy into the reddish one, which led to it glowing red, releasing a magical circle and spewing out fire.
Xie Yang didn't doubt that leaving the fire as it was would burn down his place.
Although his current cultivation level was low and he lacked a way to control fire, he was not worried as the second rune of the cauldron allows a person to control fire.
With its help, he controlled the fire pouring out of the first rune.
He gained an indiscernible connection with the fire that was spewing out of the rune on the cauldron.
He gained full command over it.
With a single thought, he caused it to split into many parts.
He extended his hand, and the wisps of fire blazed upwards to reach his palm, and then they twirled around his finger, leaving not a single burn on him in the process, which just showed Xie Ye that his young master was an expert in playing with fire.
Xie Yang flicked his finger, and the wisps of fire rushed into the cauldron through the medicinal outlets, heating it up and increasing its temperature rapidly.
When the temperature inside it reached an amount appropriate enough not to burn the ingredients, Xie Yang picked them up and threw them into the open mouth of the dragon at the apex of the cauldron.
After he threw them inside simultaneously, Xie Yang used his spiritual energy to keep them suspended within the flame. Wisps of fire were dancing beneath them. Cooked by the fire, one of them started shedding its hard outer layer, and juices along with blackish liquid came out of its petals and trickled down into the mouth of fire.
The unique mechanism of the cauldron expelled the impurities the moment it appeared.
The heat at the bottom of the cauldron was intense, and the droplets evaporated into white mist that rushed up, wanting to escape out the cauldron through the medicinal outlets.
Xie Yang's eyes narrowed as he saw the cauldron shaking back and forth.
He immediately understood what was happening, for he was an experienced and accomplished cultivator.
"Want to escape? Heh, I won't let you have your way." Xie Yang snorted in disdain at the futile escape attempt of the white mist medicinal essence.
"Brother, help me with sealing the medicinal outlets and blocking the mouth of the dragon."
"En."
Xie Ye wasn't an alchemist, but he had many refining pills.
He understood what Xie Yang wanted.
He used his spiritual energy to cover all the opening of the cauldron, making it impossible for anything to come out of it and anything to go into it.
The white mist smashed into a blue wall and bounced back into the cauldron.
"Suppress it."
Xie Yang gave another command to Xie Ye, whose spiritual energy had rushed into the cauldron through an opening he had just created and pressed down hard on the white mist, immobilizing it.
Xie Yang wiped the sweat off his forehead.
'I can finally focus on extracting the medicinal essence out of the remaining ingredients."
Different ingredients have different resistance to temperature, which also means that each ingredient has varying melting points. If a person uses a fire of high temperature to cook an ingredient that has a low melting point, they will turn it into ash. On the other hand, if they use the fire of low temperature to cook an ingredient whose melting point is high, they will end up overcooking it, affecting its quality. Thus, an alchemist must also be knowledgeable about different ingredients' resistance to temperature.
Xie Yang had a grasp on the most suitable temperature for hundreds of thousands of ingredients, including the ones inside it.
He knew that the remaining ingredients had far greater resistance to fire than the one he had already refined.
Thus, with his consciousness, he moved the fire wisps dancing at the bottom of the cauldron and made them envelop different ingredients.
He used two wisps of fire to surround the blood cherries and wrapped 16 wisps around the legs that he got from the beast.
The fire baked them for a while before viscous liquid and crimson juice came out of the bones of the beast's legs and the cherries, respectively.
On top of that, impurities also came out of them.
Again, the unique mechanism of the cauldron expelled all things impure.
Exposed to the high temperature at the bottom of the cauldron, the medicinal essences of the two ingredients also turned into gaseous forms
Xie Yang proceeded onwards and extracted the essence from the rest of the ingredients, completing the second step of refining pills excellently.