After inspecting all the equipment and finding no problems, Neji began the first step of the "Natural Energy Purification" plan—absorbing vast amounts of natural air.
Because the Natural Energy contained in the air was extremely scarce, he had to absorb more natural air in order to purify a sufficient amount of Natural Energy.
This step involved four devices: an air intake machine, an air filter, an air check valve, and an air compression tank. Their functions were exactly as their names suggested: drawing in air, filtering impurities from it, preventing air from flowing back from the tank into the filter, and finally compressing and storing the air.
The air storage tanks were enormous, each with a capacity of roughly eighty cubic meters. Six compression tanks had been placed side by side in the underground laboratory. Under high pressure, the tanks could compress natural air into a state where gas and liquid coexisted, at a compression ratio of around 1:400.
Simply put, each air storage tank could hold approximately 3,200 cubic meters of natural air—about as much air as ten one-hundred-square-meter houses contained.
This step was relatively simple. Once Neji activated the machines, streams of air were drawn in, compressed, and stored within the tanks amid a deafening rumble. About five hours later, the first tank's air compression and storage process was complete.
The second step was air purification. Though air was invisible and intangible, it actually contained many varied components: roughly 78% nitrogen, 21% oxygen, 0.92% noble gases, 0.03% carbon dioxide, 0.03% water vapor, and just 0.02% Natural Energy. It was exceedingly rare.
One cubic meter of air weighed roughly 1.29 kilograms. With 3,200 cubic meters of air in a compression tank, theoretically, one tank could yield 0.8256 kilograms of Natural Energy.
But theory was theory. Getting even half that amount in practice would already be good.
There were theoretically two methods for purification. The first was to directly extract Natural Energy from the air. The second was to remove all other substances from the air, leaving only Natural Energy behind.
The first theoretical purification method had yet to be realized. There was still no way to directly extract Natural Energy, but the second method had a traceable path and was the primary method used in this experiment.
The substances that needed to be removed were mainly nitrogen, oxygen, carbon dioxide, water, and noble gases. Based on small-scale experimental analysis and memories from his previous life, Neji knew that the most effective way to remove those substances was the "liquid air separation method."
By increasing the air pressure, the air could be transformed from a gaseous state into a liquid state. Then, by raising the temperature, liquid nitrogen, which had the highest boiling point, would vaporize first and leave the tank, achieving separation. Raising the temperature again would similarly vaporize the oxygen, which had the second-highest boiling point, and expel it from the tank.
With just those two steps, substances accounting for ninety-nine percent of the air's total mass were separated out. Then, desiccants removed the water vapor, while quicklime absorbed the carbon dioxide. At that point, only noble gases and Natural Energy remained in the air, bringing the purity to 99.06%. Only the noble gases remained to be dealt with.
The main components of noble gases were helium, neon, argon, krypton, xenon, and radon. The first five were inert gases, while the sixth, radon, was radioactive and became highly dangerous in large quantities.
To further purify the Natural Energy, Neji subjected the remaining liquid gases to a second purification.
This time, he used three methods—liquid separation, adsorption, and neutralization—across seven procedures.
Separating the inert gases alone took nearly six hours. The seven procedures had to be carried out in sequence without the slightest mistake, exhausting Neji and Zuo Mu-Duanlong. Still, the results were gratifying.
When the final procedure was completed, they finally obtained highly purified Natural Energy.
From roughly 4,000 kilograms of liquid air in the first air compression tank, only around 0.45 kilograms of highly purified Natural Energy remained!
It could be said that the air had been purified by roughly ten thousand times over.
Only then had they obtained highly purified Natural Energy. This was an ultra-high purification method achieved through wisdom that surpassed an entire planet's.
Moreover, Neji was already considering relocating the entire Natural Energy purification laboratory to the Summoning Realm. After all, the Natural Energy there was likely three to five times denser than in the Shinobi World, which would greatly speed up Natural Energy extraction.
It would be great if I could occupy a sacred land. The Natural Energy there would probably be even denser! Neji mused.
Even now, Neji had yet to figure out how to use Natural Energy.
After resting briefly, the two continued the Natural Energy purification work. They kept at it for nearly five days before Neji finally decided they had extracted enough.
Looking at the sealed Natural Energy Compression Fluid in his hand, Neji had Zuo Mu-Duanlong suspend the experiment and strictly keep the matter confidential. Neji even directly destroyed several critical components of the equipment to prevent any information from leaking.
He then left the laboratory with roughly five kilograms of highly purified Natural Energy Compression Fluid, which was all the Natural Energy extracted during that period.
Zuo Mu-Duanlong, meanwhile, wore a baffled expression. Throughout the entire process, he had merely helped turn a few machines on and off. He had no idea what they were doing, nor did he know what Neji had obtained.
That was also the best way to preserve secrecy. Even if someone captured Zuo Mu-Duanlong and searched his soul or stripped his spirit, it would be useless.
After all, no one could ever force correct intelligence from the mouth of someone who knew nothing.
Besides, Neji was still just an unnoticed student at the Ninja Academy. Who would pay attention to or care about a child barely ten years old?
After leaving the base, Neji summoned the Thunder Roc and climbed onto its back, soaring into the sky amid everyone's envious gazes.
Neji sealed the High-Concentration Natural Energy Compression Fluid inside a sealing scroll. To experiment on it, he still needed to find a relatively safe and convenient place. Konoha was too dangerous and unsuitable, but establishing a base somewhere near the village was feasible.
After getting the Thunder Roc under control, Neji decided to return to Konoha first.
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