Limestone and Quicklime

Teacher Claire's idea was actually quite simple. She had originally wanted this noble principal to strip naked and run ten laps around the square, but on second thought, the school was full of pure young girls. She couldn't pollute their hearts with such a filthy sight, so she had no choice but to give up and choose this special punishment instead.

Rainer had no desire to become the world's first cross-dressing icon. Fortunately, based on the information he had so far, he probably wouldn't be punished. On the contrary, he wanted to tease this stubborn young teacher a little.

"I accept this proposal, but Teacher Claire, what if Charlotte is right? How will you compensate this student?"

Hearing Rainer's words, Teacher Claire frowned slightly. She didn't think she would lose. Just as she had said, most Alchemy achievements over the past three hundred years had been built upon the Fire Element Combustion Theory. It was the foundation of modern Alchemy.

"What do you want me to do?"

Teacher Claire stared at Rainer as though she were looking at something disgusting, apparently imagining something unpleasant.

"Simple. As an exchange, you'll have to wear a maid outfit for a week."

Through his memories, Rainer knew that maids certainly existed in this world, and they were maids in the truest sense of the word. He hadn't actually intended to make things difficult for Teacher Claire, but she needed to taste a little bitterness, so he made this somewhat tasteless request.

"A maid outfit?"

Men of this era clearly hadn't awakened that peculiar fetish yet. Teacher Claire couldn't understand what Rainer really meant by this request, but if it was a maid outfit, did that mean Rainer wanted her to serve him like a maid?

For some reason, Teacher Claire looked a little embarrassed. She wanted to refuse, but then she reconsidered. How could she possibly lose? So she nodded and readily agreed.

"Fine. We'll use an experiment to see whose theory is correct."

The three came to an unused Alchemy classroom. Due to the school's limited funding, there weren't many actual Alchemy classes anymore, so these classrooms were often repurposed.

Rainer was somewhat surprised. The Alchemy equipment of this era already had quite the air of a modern chemistry lab. Alcohol lamps, flasks, and beakers had all become standard equipment, along with many specialized experimental instruments.

The experiment was simple: heat calcium carbonate to decompose it into calcium oxide and carbon dioxide. It was a formula Rainer knew well; on Earth, this chemical equation could be found in any middle school chemistry textbook.

Since carbon dioxide dissolved in water and was denser than air, it could only be collected by upward displacement of air. Rainer assembled the relevant apparatus. The seemingly redundant equipment made Teacher Claire frown, and she thought he was merely putting on a show.

After weighing several pieces of Limestone, Rainer first attached a guide tube to the sealed container holding the Limestone and ran it into the bottom of a sealed flask. Then, he inserted another guide tube into the upper part of the flask and extended it into a water trough to verify that gas was indeed produced during heating.

He lit the flame. Since an ordinary alcohol lamp couldn't steadily heat the Limestone to the temperature required for the reaction, Charlotte assisted by casting a beginner-level Flame Spell. This was also the first time Rainer had seen magic with his own eyes. Blazing flames danced at Charlotte's fingertips without scorching her skin in the slightest, changing shape according to her will. It was truly impressive.

"At most, heating it like this will cause some air to expand and make bubbles come out of the tube. You're just wasting—"

Before Teacher Claire could finish, the guide tube submerged in the water trough released a bubble with a plop.

But that was only the beginning. Soon, an unbroken stream of bubbles emerged from the tube. There was no doubt that new gas had been produced inside the apparatus.

"This..."

Teacher Claire was speechless. She stared fixedly at the experimental setup as though it were some sort of magic trick.

Three times in a row, Rainer and Charlotte repeated the process and produced three bottles of gas.

Of course, Rosen didn't discard the Quicklime produced by calcination—that was, the calcium oxide. He tossed it into a beaker of water. The white stone immediately began to sizzle and emit white smoke, quickly dissolving into the water and vanishing from sight.

Calcium oxide reacted with water to form a calcium hydroxide solution. In chemistry, one of this solution's greatest uses was testing for carbon dioxide.

Naturally, Rainer had prepared this solution to verify whether his chemistry knowledge matched this world's Alchemy knowledge. Without a doubt, they were the same. Although Rainer still couldn't explain what magic actually was, at least he had confirmed that this world's foundations were no different from Earth's.

"As you can clearly see, gas was produced during the experiment, wasn't it, Teacher Claire?"

Rainer asked, watching the young dean of instruction's expression with great interest. He found it quite amusing.

Teacher Claire remained silent, her mind whirling with thoughts.

According to Master Hohenheim's theory, during combustion, the Fire Element within an object was released and became flame, while what remained was ash. Yet it had never mentioned the existence of gas. The mass lost during combustion was generally believed to be the mass of the Fire Element, but now it seemed this gas accounted for part of it as well? Or was this the true nature of the Fire Element?

Seeing Teacher Claire remain silent, Rainer lit another match and held it to the mouth of one of the flasks. The once vigorous flame went out in an instant. Clearly, this gas was not the Fire Element. Instead, it was some kind of gas capable of preventing combustion.

Teacher Claire was completely speechless.

Rainer didn't stop there. He poured one bottle of gas into the liquid in which Quicklime had dissolved, and the water level in the flask began to rise steadily. At the same time, the once clear solution turned cloudy, as though grayish-white sediment had appeared.

Now even Charlotte found it somewhat strange. Her own experiment had ended just now. The rest looked like this principal's own improvised addition.

Rainer weighed the cloudy solution and the experimental apparatus, then subtracted the weight of the apparatus alone and the water. Comparing the resulting figure with the mass of the Limestone before the experiment, it was obvious that, excluding measurement errors, the two were almost exactly identical.

"This means that before and after the experiment, the mass of the Limestone was distributed into the mass of this gas and the mass of Quicklime, rather than the mass of the Fire Element and ash described by the Fire Element Combustion Theory."

Rainer concluded. He knew perfectly well that the principle behind this experimental phenomenon was one of nature's most universal and important fundamental laws, one of the cornerstones of civilization's progress on Earth. Though he didn't yet know much about this world's development, Rainer believed this law would play a vital role in its future.

To begin with, this series of experimental phenomena dealt Teacher Claire a tremendous blow. She only felt the world spin, her vision go dark, and then she fainted.