This experiment was not only of great practical significance, but also an excellent educational opportunity. Therefore, in addition to the participants Agatha, Sylvie, Charmes, and Camo Strale, Roland also called over the other members of the Witch Union, Carter, Iron Axe, and Barov. To accommodate these twenty-odd people, the experiment site was chosen as the Fifth Laboratory, which had the largest space.
For the first attempt, the fractionation container was not made too large, about the height of a person and one meter in diameter, similar to a tower. The inside of the container was divided into three layers, with the bottom layer for air intake and the top two layers for exhaust.
Before the separation began, Roland gave everyone a simple chemistry lesson, telling them what might happen, and raising a few small questions to let everyone find the answers themselves—in addition to arousing the interest of the listeners, it could also greatly enhance the teaching effect, which was also a common technique used by chemistry teachers.
"...In theory, when Agatha lowers the temperature inside the container, the air will gradually condense into liquid, and drip to the bottom layer through the perforated partition. So when you observe liquid accumulating at the bottom, tell us."
Because it was impossible to see directly, Sylvie had to observe through the container and describe the changes. Therefore, Roland spoke in great detail on this part.
Sylvie nodded dubiously, "Can you really see liquid appear? Isn't it just water vapor in the can?"
"Don't worry, liquid air is light blue, which is completely different from water vapor." Roland waved his hand and said, "Moreover, at that temperature, the water vapor has already solidified into ice crystals." Then he made a gesture to Agatha, "Then let's begin."
"Wait...shouldn't the hole at the bottom of the container be blocked?" she asked.
"We'll block it later, otherwise there won't be enough air in the can to observe obvious changes." Because it was just an experiment, Roland used the simplest method to draw in air—when the temperature inside the can drops rapidly, the pressure will decrease accordingly, causing the outside air to continuously flow into the can. Doing this during normal production is simply not worth the loss, because the cold air will continuously escape, wasting energy. However, Agatha uses magic, and the cooling efficiency far exceeds any refrigeration machine, so Roland was too lazy to prepare an air pump for inflation.
Agatha took a deep breath and placed her hands on the fractionation tower.
Within a few breaths, a whistling sound appeared in the intake pipe, which was the sound of air rushing in quickly. Layers of white frost emerged around the pipe opening at a speed visible to the naked eye, and continued to expand—the moisture in the air quickly condensed under the overflowing low temperature and adhered to the outer wall of the container. Anna turned Blackfire into silk threads, clearing away these constantly thickening ice crystals.
After a while, Sylvie said in surprise, "I see liquid appearing on the partition, but more of it is white frost."
"The white frost may be water vapor that has rushed in, or it may be crystallized carbon dioxide," Roland explained, "Considering that the carbon dioxide content in the air is extremely low, most of it should be water vapor."
If it were formal production, the air would have to be dried before being drawn into the fractionation tower, otherwise the condensed water vapor would easily block the separation plates and exhaust holes, reducing production efficiency.
About a quarter of an hour later, Sylvie reported that the bottom of the container was filled with blue liquid, and Roland then had Soroya block the intake pipe and seal it with coating.
Next was the crucial temperature increase.
According to the different melting and boiling points of nitrogen and oxygen, nitrogen gas will reach its boiling point first and escape upwards as a gas, thereby achieving separation. He didn't remember the specific value of this temperature, and currently had no means to measure it, so Agatha could only grasp it herself. The specific manifestation was that gas was discharged from the exhaust port at the top of the fractionation tower, and the remaining liquid at the bottom would become more and more blue, which meant that the purity of liquid oxygen was constantly increasing.
Fortunately, Agatha was no stranger to controlling magic. She precisely adjusted the cooling rate to make it slowly rise, and soon Sylvie also observed the liquid surface boiling phenomenon. Bubbles began to emerge from the coated tube passing through the water, and Camo quickly collected several bottles of gas using the water displacement method.
"Is this nitrogen?" Lily pouted, "You can't see anything at all."
"This is the first question I mentioned earlier," Roland asked, "How to prove that it is different from air?"
"Ignite it," Lily took the lead in answering, "《Elementary Chemistry》 says that combustion requires oxygen. If it is another gas, it should extinguish the burning wood instantly."
"You'll know if you re-cool it into liquid," Agatha said after thinking for a moment, "Didn't you say that nitrogen is colorless after liquefaction?"
"Or you can extract the remaining liquid in the container and prove that the latter is pure oxygen, which can also prove the diversity of air components." Anna said.
The scene completely became a stage for academic masters to perform. One test method after another was proposed and then discussed with each other. Only a few people's voices remained in the laboratory. Roland looked around and found that Nightingale, Andrea, Maisie, and a group of witches, as well as the Chief Steward of the City Hall and Chief Knight Carter, all looked blank. The First Army Commander Iron Axe maintained the same expression at all times, probably agreeing with whatever he said.
Okay, Roland sighed in his heart. It seemed that this chemistry class was a bit beyond the syllabus.
If there was anyone who could feel His Highness the Prince's joy now, it would probably only be Camo Strale and Charmes.
"Your Highness, this is really...amazing," the young alchemist exclaimed, "You have proven the correctness of 《Elementary Chemistry》. I am afraid that all alchemists would not have expected that even the air that is everywhere around them is so complex."
"With pure oxygen, can we observe more violent oxidation reactions? I have many more experiments I want to try," Camo said excitedly.
Roland nodded, but another idea suddenly popped up in his mind.
Nitrogen is the main raw material for artificial ammonia synthesis. Under high temperature, high pressure, and with the addition of a catalyst, it can react with hydrogen to obtain ammonia. The latter can not only be used to manufacture nitrogen fertilizer, but also to synthesize nitrogen oxides, thereby producing nitric acid. But to achieve this process, there is still a lot of work to be done, such as air pumps, vacuum gas storage tanks, and a series of complex reaction equipment. Even if White Paper can provide the function of a catalyst, it will require repeated experiments.
Now that he has pure oxygen and pure nitrogen, why not directly produce nitric oxide?
Admittedly, the chemical industry chooses to use ammonia to produce nitric acid because the oxygen-nitrogen reaction is an energy-absorbing reaction and cannot proceed spontaneously. It requires an external supply of energy, such as electric discharge—heating the gas to thousands of degrees instantly through an electric arc, which is also why the soil is more fertile in places where lightning frequently strikes. Because of this, this method requires high equipment and consumes a lot of energy, so it is not suitable for formal production.
But if there is an urgent need to increase production capacity, this production method is the most efficient. No catalyst is needed, just continuous discharge...or use other means to achieve the high temperature generated by the electric arc.
Roland naturally thought of Blackfire.
The heating efficiency of Blackfire is not worse than that of an electric arc, and the burden on Anna is also extremely low. As long as the nitrogen and oxygen are purified, mixed in proportion, and poured into a sealed reaction kettle, nitric oxide can be continuously generated.
He decided to try this method.