The Discovery of Nitrate

Several girls went to collect wood to make charcoal, while Lu Zhe continued making clay embryos.

The partners worked busily until nightfall, making two more batches of brick embryos and a large amount of charcoal.

As it was getting late, the brick embryos were not yet dry, so it was not yet time to fire them. They needed to be aired overnight first before they could be fired.

Let's call it a day for the hard work today.

By now, the water reservoir was already full.

Compared to seawater, the water flowing down from the mountains was four to five degrees cooler.

Although it could not be called cool either, it could still provide some relief from the scorching heat.

The girls with their dirty, sweaty faces simply could not resist the allure of the pool and rushed in to take a cold shower.

Looking back, Yongqiang and Shen Bing were left listless from the heat.

Lu Zhe fetched buckets of water to pour over himself, and the two oxen let out sounds of delight as they crowded towards Lu Zhe, competing to be doused.

Lu Zhe had no choice but to splash them with several more buckets before they finally stopped.

Just then, Lu Zhe noticed that the flowers on the cow dung pile had all wilted.

What was going on?

He pulled out one plant to take a look, and the roots had started to rot.

He pulled out a few more, and it was the same problem.

Lu Zhe was rather puzzled.

Weren't cow dung and flowers a perfect match?

Why did it burn the roots?

Was it because there was no compost?

Or was it that they ultimately belonged to different worlds, never able to enter each other's hearts?

How superficial...

As Lu Zhe looked at the pile of cow dung, his thoughts wandered a bit too far.

But the most confusing problem right now was not this.

He recalled how a bucket of instant noodles had ruined the teacher's succulents before. And now a pile of cow dung had ruined the girls' wild flowers.

If this continued, he would soon have the reputation of a flower-destroying brute.

He should transplant them somewhere else!

Because the sunlight was too intense during the day, Lu Zhe decided to plant the flowers behind the cow dung pile.

There were rocks, mud walls and fences here to provide shade and block the direct sunlight all day.

Lu Zhe took a shovel and started digging small pits to plant the flowers in.

Then he saw something unusual.

There was a thin layer of frost-like salt deposits on the exposed rocks.

The legendary saltpeter?

Lu Zhe knew about this stuff but it was his first time seeing it.

He was rather curious.

The ammonia in urine would convert to nitrates at certain times and adhere to the rocks.

In ancient times, commoners who could not afford salt would extract saltpeter from outhouses to eat. This was what they were eating!

Although it was a bit disgusting, they had no choice.

The human body would suffer greatly if it lacked salt. Without sodium chloride, they had to use sodium nitrate as a replacement.

Additionally, saltpeter, brimstone and charcoal could also be used to make gunpowder.

It wouldn't be bad to make some firecrackers to scare away the monkeys either.

But if they were not killed instantly and were left bloodied and screaming in pain, imagining that scene made Lu Zhe feel somewhat merciless.

So if it was to be done, the explosions had to be powerful enough for an instant kill. That would be the most humane.

Besides substituting for edible salt and making gunpowder, saltpeter had a third function!

Cooling!

Most nitrate salts would absorb heat when dissolving in water. There were even specialized saltpeter ice laborers in the Tang dynasty.

Of course, they used saltpeter minerals collected from mountainsides.

How would the cooling effect be with just this little bit of saltpeter?

He would try it out first!

Lu Zhe tossed the flowers aside, took a yogurt cup and carefully started collecting the saltpeter salt.

Soon he collected a small cupful.

He would test it out.

Lu Zhe fetched a large sized tin can, filled half of it with water, then poured in the saltpeter salt, slowly stirring it with a bamboo stick.

Lu Zhe distinctly felt the water temperature dropping. After a while, moisture condensed on the outer wall of the glass jar while the water inside continued cooling.

It really worked!

He placed the tin can on his chest and immediately felt his whole body cooling down pleasantly.

He quickly soaked a small bottle of water in the tin can.

Soon, the girls finished showering and came out wrapped in broad leaves.

"What are you doing there, Lu Zhe?"

"Something good!"

Hearing that it was something good, the girls crowded over curiously. Jiang Yao asked, "What is it?!"

Lu Zhe shook the tin can, "Feel this, it's very cool!"

Then Jiang Yao placed her hand on Lu Zhe's chest.

"Wow, it really is cool!" Jiang Yao exclaimed, "What's going on with you, Lu Zhe?!"

Lu Zhe frowned, "I just had the tin can against my chest for a while, that's why it feels cool!"

Qian Qian said, "Let me feel!"

Guo Er said, "Me too!"

Ning Shu grinned cheekily, "Haha, an ice-cold little bean sprout!"

"Stop putting your hands on me!"

Lu Zhe protested, "Ladies! I asked you to feel the tin can, not me!"

Shen Bing was the most sensible and restrained. She touched the tin can and also gasped in surprise, "It's so cool, Lu Zhe! How did you do it?!"

"When saltpeter dissolves in water, it absorbs heat and cools the water down." Then he took out the bottle inside, "Chilled water, everyone can try it!"

There was only enough chilled 350ml water for everyone to have one sip, but it was enough to instill a sense of hope and comfort in their hearts.

"Where did you get the saltpeter from?"

"The stone wall behind the cow dung pile."

"Ah? So we just drank cow dung water?"

"Of course not. It was just the sodium nitrate crystals that precipitated out. The water in the bottle is clean."

Shen Bing said, "Last time, Lu Zhe and Xiaoguo went to the rocky cliffs. If you didn't return on time, we might have had to extract salt this way to eat."

Jiang Yao complained, "We've been eating urine salt for a few days already."

Qian Qian spoke softly, "If we think about it as our own, I guess it's still acceptable."

Jiang Yao sighed, "Qian Qian, something's not right with you again!"

"No there isn't..."

Ning Shu sighed, "It's a pity there's so little of it. Once we use it up it'll be gone."

"No, this can be used indefinitely!"

"Used indefinitely?"

Lu Zhe nodded, "Sodium nitrate does not actually react with water, it just dissolves in it. Using boiling, we can obtain the sodium nitrate crystals again. When added to water again, it will still absorb heat and lower the temperature."

Tang Xiaoguo said happily, "So taking just a tiny bit each time, it can be used indefinitely?"

"There will be some loss during the boiling process, but with more stock, it can indeed be used indefinitely."

"How can we obtain more of it?"

Shen Bing pondered, "Either find a saltpeter mineral source, or boil large vats of feces, or collect it bit by bit from beside the dung piles."

"Boil vats of shit?! Are you serious?" The girls' eyes widened:

"You can't be joking right?"

"Such a hentai idea, would it be real?"

"Do we even have large vats?"

"It's precisely because we don't have large vats that your ideas of boiling shit will remain but a dream!"

The girls spoke in unison, "We are absolutely not disappointed by that!"

Ning Shu asked, "Lu Zhe, what do you estimate is the possibility of finding saltpeter minerals on this island?"

Lu Zhe said helplessly, "How would I know? At least in all the places I've explored, I haven't seen any traces."

Jiang Yao nodded, "Which means we can only collect it bit by bit from beside the dung piles, right?"