Chapter 378: Oxygen and Nitrogen
Translator: Meh/TransN Editor: - -
Agatha, Sylvie, Chavez and Kyle Sichi would conduct the experiment. Carter, Iron Axe, Barov and all the other witches of the Witch Union were also required by Roland to come to the lab, as it was an experiment of great practical and educational significance. The fifth laboratory was chosen for this event, given that it was the largest lab and had enough space for the two dozen people.
Considering the experiment was the first of its kind, Roland had built a tower-shaped vessel which was only as tall as a man with a diameter of one meter instead of a giant fractionation vessel. The inside of the vessel was divided into three parts. The air would enter the vessel through the bottom part and come out through the two parts above.
Before separating the air, Roland gave them a simple lecture on chemistry, telling them what was going to happen and putting forward a few questions for them to think about and try to answer. It was a trick frequently used by chemistry teachers to intrigue their students and enhance the effects of the lesson.
"... theoretically, when Agatha cools down the vessel and brings down its internal temperature, the air inside will gradually be condensed into liquid, and drip down into the bottom of the vessel through the holes in the plate. So when you see liquid at the bottom, please let us know."
Roland explained to Sylvie in detail, because no one except her could directly see into the vessel and describe the changes happening inside.
Sylvie nodded somewhat skeptically, "Will I really see liquid appear? Will it not be only the water vapor inside the vessel?"
"No, it's different. The liquefied air is light blue, completely different from water vapor." Roland shook his head and explained further, "Plus, at that temperature, the water vapor will be solidified into ice crystals long before the air." Then he made a gesture toward Agatha and said, "Let's get started."
"Wait... Do we not have to plug up the hole in the vessel's bottom now?" she asked.
"Block it up later. Otherwise, the vessel won't have enough air inside to bring about significant changes." As this was only an experiment, he chose the easiest way for air intake—when the air temperature inside the vessel was rapidly lowered, the internal pressure would fall, and thereby draw the air into the vessel. In mass production, cooling down the air cost too much energy and the cool air would run off continuously. Therefore, this cooling method was considered inefficient and rarely applied in practice. However, Agatha's magic power could bring down the vessel's temperature more efficiently than any refrigerators, saving Roland the trouble to prepare an air pump.
Agatha took a deep breath and pressed her hands onto the fractionation vessel.
About half a minute later, whistling sounds could be clearly heard as the air was rapidly passing through the air intake pipe. White frost could be seen by the naked eye around the pipe hole, and its area gradually expanded—the water in the air nearby was quickly solidified, and then adhered to the vessel. Anna turned her Blackfire into threads to clean up these continuously thickening ice crystals.
"I see some liquid appearing on the plate, but there's more white frost inside." Sylvie said in an amazement a moment later.
"The white frost may be the solidified water vapor or the crystallized carbon dioxide," explained Roland. "Considering that there's only a small portion of carbon dioxide in the air, most of it should be solidified water vapor."
In normal production, air must be dried out first before being sucked into the fractionating vessel. Otherwise, the solidified water vapor would block the parting plates and the holes, and thus decrease the production efficiency.
Several minutes later, Sylvie reported to Roland that the bottom part of the vessel had been filled with light blue liquid. Roland immediately instructed Soraya to block the holes in the air intake pipe and seal them with coatings.
The next thing to do was heat the vessel, a crucial step in this experiment.
When the liquefied air was heated, the nitrogen would first reach its boiling point, vaporize and run off due to the different boiling points of nitrogen and oxygen. In this way the two could be separated. Due to the fact that Roland forgot the exact temperature at which nitrogen reached its boiling point, and that he had no way to measure it either, it all depended on Agatha to control the temperature. If she managed to heat the fractionation vessel to the right temperature, the nitrogen gas would come out via the exhaust pipe and the liquid in the bottom part would grow bluer and bluer, with an increasing purity of oxygen.
Fortunately, Agatha was familiar with magic power control. She accurately adjusted the cooling range, increasing the temperature slowly. After a while, Sylvie observed that the liquid was boiling. She saw bubbles around the coating pipe which was plunged into the water. At the same time, Keymor quickly collected several bottles of gas, using the drainage gas-gathering method.
"This is nitrogen?" Lily twitched her lips and said, "I can't see anything at all."
"That's exactly the first question I put forward earlier," Roland said, "How do we prove it's different from the air?"
"Test it with a piece of burning wood," Tilly answered first, "it'll extinguish the fire instantly if it's nitrogen. According to Elementary Chemistry, everything requires oxygen to burn."
"Cool it down again and condense it back into liquid," Agatha said after thinking for a while, "Didn't you say that liquefied nitrogen is colorless?"
"How about pouring out the remaining liquid in the vessel and proving it's pure oxygen? By doing so we can verify the diversity of air composition." Anna suggested.
In the lab, only a few quick learners eagerly proposed different methods and began a heated discussion, while the others remained silent. Roland looked around and found Nightingale, Andrea, Maggie, the City Hall Director and the Chief Knight Carter all seeming confused and at a loss. Iron Axe, the commander of the First Army, on the other hand, always maintained the same facial expression. Roland believed that Iron Axe would probably give him a nod no matter what he said.
Roland sighed silently. "It looks like this chemistry lecture is a little above their level."
Perhaps the only ones who could really share His Highness's happiness at this moment would be Kyle Sichi and Chavez.
"Your Highness, it's really... amazing," the young alchemist exclaimed, "and you've proven what's written in the Elementary Chemistry is true. I'm afraid it has never occurred to alchemists that even the air around us is so complicated."
"With pure oxygen, it's possible to observe more intense oxidation reactions, right? I have a lot more experiments to try out now." Kyle said in excitement.
Roland nodded and an idea suddenly jumped into his head.
Nitrogen was the most important raw material for synthetic ammonia. It can react with hydrogen at a high temperature and under high pressure to form ammonia that can be used to manufacture nitrogenous fertilizer and synthesize nitrogen oxides, which can be further used to produce nitric acid. However, in order to carry out this plan, much work needed to be done and many pieces of equipment needed to be built, such as air pumps and vacuum gasholders. Even if Paper has the magic power to work as a catalyst, it would require repeated testing.
Now, with pure oxygen and pure nitrogen, why not try to produce nitrogen monoxide?
The reaction of oxygen and nitrogen in nature wasn't an automatic one because it was an exothermic reaction that required external energy, such as an electric discharge in which an electric arc can instantly heat the air up to a temperature of thousands of degrees. That's why places where thunder and lightning frequently occurred had more fertile lands, and why ammonia was often used instead to produce nitric acid in the chemical industry. The electrical method of production was not a common practice as it costed too much energy and required extremely high-quality equipment.
Yet it was the most efficient method in case of an emergency, as it didn't even require any catalyst, simply constant electric discharge... in fact, any other means that produce the extremely high temperatures that electric arcs can achieve will do.
Roland naturally thought of Blackfire.
He was sure that it was easy for Anna to manipulate her Blackfire, which worked as an efficient and powerful electric discharge. Now all they needed to do to produce nitrogen monoxide was mix purified oxygen and purified nitrogen in the proper proportions and pour the mixture into an airtight reactor.
He decided to give it a try.