Release that Witch Chapter 378
Just a heads up to everyone, I’m still sick. And also, this chapter had a lot of technical stuff which made it a little hard.
For a quick video on fractional destillation of air, here:
The experiment was not only of great practical significance, but it also served as an excellent educational opportunity. Therefore, in addition to the main participants: Agatha, Sylvie, Chavez, and Kyle Sichi, Roland also called the rest of the Witch Union members along with Carter, Iron Axe and Barov. In order to accommodate the large crowd, the fifth laboratory was selected since it was the largest and most spacious one.
Since it was the first experiment, the fractional distillation towers were not that big, only about a person's height and with a diameter of a meter. The container was divided into three layers, the bottom one was for the intake and the upper two layers were used for venting.
Before the process began, Roland first gave a quick chemistry lecture for everyone in which he told them what might happen, and by letting them answer a few questions he wanted to have them arrive at their own answer—if he were to arouse the interest these people had in the experiment, it could greatly improve the effect of teaching, which was a usual practice for chemistry teachers.
"…So, in theory, after Agatha lowers the internal temperature of the container, the air will gradually condense and turn into a liquid, which will then drip down to the bottom through the perforated plate. Therefore, tell us when you see liquid at the bottom."
Since he was unable to get a clear visual reference, Roland directed Sylvie to observe through the container, and describe the changes to him, asking her to be particularly detailed about it.
Sylvie acknowledged with a nod, showing a little skepticism, "Can that liquid really be seen? It won't be just water vapor inside the container, right?"
"Don't worry, liquid air has a light blue hue, which is completely different from the colorless water." Roland waved his hand and continued in order to reassure her, "And at that temperature, any water vapor trapped inside the container would have turned to ice crystals long before the air shows changes." After that he turned towards Agatha and said, "Now lets begin!"
"Wait… shall we start while the hole at the bottom of the container is not blocked?" she asked.
"We'll do it later, or else the air inside might not be enough to get noticeable results." Because this was only a test, Roland had chosen the simplest way to get air inside—as the temperature of the container suddenly dropped, the pressure would start to decrease, making the air outside rapidly pour in into the container.
In the conventional production, this method would not live up to the task, due to the constant intake of new air, the energy wasted cooling it down would be enormous. But with Agatha's magic, the cooling efficiency was far greater than any modern day's refrigeration unit, so Roland didn't have to use any energy preparing an air pump.
Agatha then took a deep breath and proceeded to press her hand onto the fractional distillation tower.
Among the several sections, a whistling sound could be heard, that was the sound of the rapid influx of air coming from the intake pipe. A layer of frost soon appeared around the nozzle of the pipe and started growing in size—the moisture in the air rapidly condensed at the incredibly low temperature, and stuck itself to the outer wall of the container.
Anna used her black fire, turning it into a thin thread and with it, she cleaned up the ice crystals that started to grow on the exterior of the container.
Not long after, Sylvie spoke with astonishment in her voice, "I see liquid forming on the plate, but there is also more of the white frost inside."
"That white frost may be due to the humidity in the air, it may also be frozen carbon dioxide," Roland proceeded to explain, "But given the very low levels of carbon dioxide that might be present in this air, it most likely is water vapor."
In the normal official production, before the air was pumped into the fractional distillation tower, it went through a drying treatment first. Otherwise, the humidity present in the air would condense and easily clog the perforated plate at the bottom and the ventilation vent, making the production less efficient.
Around seven minutes later, Sylvie reported that the bottom of the container had been filled with a blue liquid. Roland then had Soraya plug the intake hole and seal it with a layer of coating.
The next key step was warming it up.
Due to the different boiling points of nitrogen and oxygen, the nitrogen would be the first one to reach the boiling point, turning into gas and trying to escape, effectively achieving the separation of the gases. Although he didn't remember the specific temperature values, there were no instruments to measure it even if he did, he could only rely on the grasp Agatha has of the temperatures. Summing up the process, after the nitrogen started turning into a gas, it would be discharged by the exhaust pipes at the top of the tower, and thus, the remaining liquid at the bottom would become more and more blue. This meant that the purity of the liquid oxygen was indeed increasing.
Fortunately, Agatha's magic control was very good, so she adjusted the cooling range with precision, in a way that the temperature slowly started to pick up. After a moment, Sylvie observed the boiling phenomenon taking place on the surface of the liquid. Bubbles began to emerge from the coated tube that was submerged in water, and Kyle quickly collected it in several bottles using the drainage gas-collecting method.
"Is this nitrogen?" Lily asked, "There seems to be nothing special in the bottles."
"That is the first question of my experiment," Roland said, "how can it be proven that it is different from normal air?"
"With a burning stick," Tilly was the first to answer, "《Elemental Chemistry》 says that oxygen is required for a flame to be maintained, and if the bottles contain another gas, the flame of the burning stick should be extinguished instantly."
"Just cool it back into a liquid." Agatha said after pondering for a moment, "Didn't you say that the liquid nitrogen was colorless?"
"Or we can also move the remaining liquid out of the container, and after proving that the latter is pure oxygen, it can also prove the diversity of the air components." Anna expressed her idea.
The scene soon turned into a heated discussion, after a test method was proposed, it was followed by a debate among the few people in the laboratory that had enough knowledge to take part in it.
Roland looked around, and found Nightingale, Andrea, and Maisie, among the witches, the City Hall Chief Minister and the Chief Knight Carter, with a blank look on their faces.
The First Army regulations commanded Iron Axe to maintain an expression-less face at any time, and he would probably just nod and answer with a yes to whatever he asked.
Roland just gave a soundless sigh, it appeared that the chemistry class was slightly over the top to some of the people present.
If there were anyone who could feel the same joy as the prince, it would probably be only Kyle Sichi and Chavez.
"Your Highness, this is really… like magic," the young alchemist exclaimed, "You have proved the theories in 《Elemental Chemistry》 are correct. I dare to say that none of the alchemist ever expected the air around us to be so complicated."
"With pure oxygen, is it possible to observe a more intense oxidation reaction? I really have a lot of tests ahead of myself." Kyle said with excitement in his voice.
As Roland nodded, another thought popped out in his mind.
Nitrogen was the most important raw material of artificial ammonia. By reacting with hydrogen and a catalyst in a high pressure and high temperature environment, he could heat ammonia. But the latter could also be used not only in the production of nitrogen-based fertilizers, but also to synthesize nitrogen oxides, thus making nitric acid production feasible.
But if he wanted this complex process to be realized, there was still a lot of work to be done, such as making air pumps, vacuum tanks, and several complex reaction equipment.
Even if Paper could provide the role of catalyst, he would still need to run several tests. But now that he has pure oxygen and pure nitrogen at hand, why not try the direct production of nitric oxide?
It was true that the chemical industry chose to use ammonia to make nitric acid. It was because the oxygen and nitrogen reactions belonged to the energy-absorbing reactions, therefore they cannot be spontaneous, and they need an external supply of energy, such as an electrical discharge—heating the gas to thousands of degrees by an electric arc instantaneously. This was also the reason why the soil was more fertile in places where lightnings often struck.
Because of this, this type of equipment required a very high energy consumption, therefore not making it optimal for industrial production. But if there was an urgent need to increase capacity, this method of production was the most efficient, since a catalyst was not needed. The only thing needed was a continuous discharge… or other means to achieve the high temperature generated by the electric arc.
Roland thoughts obviously wondered towards Anna's black fire.
The thermal efficiency of the black fire is probably not worse than an electric arc, and it is a very low burden on Anna. So as long as the nitrogen and oxygen are purified, and mixed in a closed reaction chamber, nitric oxide can be continuously produced.
He decided trying this method out.