"Now then, to continue from yesterday..."
Soleil and Luna had insisted they would handle the cleanup and sent her on her way, so Elsa joined Jin in the workshop that morning.
"My Lord, the pressure vessels for the air are complete."
Laojun’s report came through, and soon after, a Smith arrived hauling a prototype.
It was an adamantite cylinder, twenty centimeters in diameter and sixty centimeters long. With a wall thickness of approximately two millimeters, it weighed about seventy-five kilograms.
"This container can withstand pressures of up to one thousand atmospheres."
High-pressure cylinders on modern Earth typically hold around one hundred and fifty atmospheres, which served as a testament to just how incredibly sturdy this vessel was.
"That was fast..."
It appeared to be properly equipped with a pressure-reducing valve as well.
"Yes, it is functional."
In truth, it had been finished early the previous night, but Laojun had spent some time in trial and error because the flow rate was inconsistent when he first tried to discharge the compressed air. The valve's design was simple, utilizing a spring to ensure the escaping air pressure remained constant. The principle was quite similar to many of the valves used on modern Earth.
"You've done a great job."
"I am honored by your praise."
Jin wanted to complete the spaceship as soon as possible, so he welcomed this kind of labor-saving support. Laojun understood this well, which was why he made a point to handle everything that didn't strictly require Jin’s personal touch.
"By the way, My Lord, regarding the moonlight grass..."
"Yeah, what about it?"
"Sample collection was completed last night. Additionally, it seems Saki-sama has been conducting her own research on the subject at her home."
"Saki has?"
Jin recalled that she had indeed shown a keen interest in it back at Kari Village.
"Jin-nii, do you want to go see?...If you're too busy, I can go instead."
Elsa made the suggestion out of concern for him, but after a moment's thought, Jin decided that since it was an important matter, he should go as well.
"Let's see... Yeah, let's go together."
"Okay."
Elsa had no reason to refuse; if anything, she nodded with visible delight.
Jin, Elsa, Reiko, and Edgar used the Warp Gate located on the grounds of House Eschenbach. After adjusting for the time difference, it was 8:30 AM local time.
"Jin-sama, Elsa-sama, welcome."
Aaru noticed their arrival and came out to greet the group.
"Is Saki here?"
"Yes, she is in the laboratory."
Having confirmed Saki’s whereabouts, the group headed straight for the lab.
"Saki—are you in there?"
"One present!"
"We don't need two."
"How mean....Wait, is that mean?"
Trading lighthearted banter, Saki peeked her head out from the laboratory.
"Hey, Jin, Elsa. Good timing."
"Saki, what were you working on?"
"I’d prefer you say I was researching... Simply put, I've been studying moonlight grass."
This was the phosphorescent plant used for nightlights they had discovered in Kari Village, at the entrance to the land of Mitsuho. Saki had been fascinated by it during their visit, so it seemed she had collected some samples of her own.
"I wanted to know what specific component of the moonlight grass makes it glow."
She explained that she was trying to perform an extraction.
"The acids, alkalis, and solvents I can get my hands on here are limited, so I was thinking of heading to Hourai Island if I couldn't make it work here."
The laboratory on Hourai Island was stocked with reagents provided by No. 700672, so such inconveniences were rare there.
"Then you should have just done that from the start," Jin said, to which Saki replied with a wry smile.
"...Well, there was a reason I couldn't really do that."
Saying so, she gestured with her eyes toward the back of the lab.
There, they saw him.
"Hey, Jin, Elsa. It's been a while."
It was Goose. Since his naturalization, it had been arranged for House Eschenbach to look after him until he grew accustomed to the country and could support himself.
"Hey, Goose."
"Hello."
It appeared Goose was assisting Saki with her experiments.
"So, specifically, what have you two been doing?"
"We've been mixing crushed moonlight grass into various 'solvents' to see if the component dissolves."
"I see. What have you tried so far?"
"Water, hot water, oil, vinegar, alcohol, and even limewater."
In addition to the knowledge she had gained through Trans Info, Saki had been studying reference books compiled by Laojun, giving her chemistry knowledge roughly equivalent to a high school student. She was conducting her experiments by putting that knowledge to use.
"I see. You're testing its solubility."
"Yeah. It seems to dissolve somewhat in water."
Plant cells are surrounded by sturdy structures called cell walls, unlike animal cells. These cell walls are made of cellulose... Jin had some somewhat fuzzy knowledge along those lines.
"And here’s the thing, Jin. It dissolves in hot water too, and this is what I got after cooling and filtering that hot water."
Saki held up a test tube.
"This solution... it’s phosphorescent!"
"Isn't that amazing?"
The phosphorescent component extracted from the crushed moonlight grass does not dissolve in cold water, but as the temperature increases, it dissolves well once the water reaches 70°C or higher. Furthermore, once dissolved, it does not seem to precipitate even if the temperature is lowered.
"I’m thinking that if I boil this down, I might be able to create a phosphorescent paint."
"I see."
Jin was pleased; he had just received an excellent hint for his emergency lighting.
Then Goose added, "I wonder if we could cultivate this plant in this country?"
If that could be achieved, it would be a significant contribution.
Jin and the others then observed an experiment involving the concentrated solution after it had been boiled down.
"Oh, that's quite bright."
By concentrating the solution, the glow had become much more intense.
"Hehe, it would be wonderful if we could apply this to nightlights," Saki said, looking quite pleased with herself.
"I wonder what kind of substance it actually is?"
Unfortunately, the Analyze magic only reveals information the caster already understands, so it couldn't identify an unknown substance.
"I've at least confirmed that it’s completely unrelated to free ether."
Through Aaru’s cooperation, they had been able to determine that it was not a magical phenomenon.
"That's excellent news."
For Jin, who was searching for light sources that did not rely on free ether, this was invaluable information.
After having lunch with Saki and Goose, Jin and Elsa left House Eschenbach.
"Well, that gives us a solid prospect for the emergency lights."
"Mm."
Back at the Hourai Island laboratory, the two faced each other in Jin’s workshop.
"...It's not just for the spaceship. It'll benefit the whole world."
"Yeah. But we'll have to research it much more thoroughly. We can't just leave it all to Saki."
If they succeeded in cultivating moonlight grass, they would have access to an inexpensive source of light. Separately from Goose's efforts, Jin intended to pursue this on Hourai Island as well.
"Even with cultivation, we have to find the optimal conditions."
Should they mimic the natural environment perfectly, or would changing certain factors be better? If they changed them, how would that affect the concentration of the phosphorescent substance? There were many things to do, but he had no choice but to entrust the bulk of the work to Laojun.
"Jin-nii, are you... feeling a little rushed?" Elsa asked, sounding slightly worried.
"Yeah. I might be, just a little."
"...Spaceship development is going well. It's on schedule—actually, it's a bit ahead. So, why?"
At her question, Jin answered with a somber expression.
"I’m just... anxious, I guess."
"Anxious?"
"Yeah. After all, even in the world I came from, space development and space travel were still very much in their infancy. Now we're trying to achieve that by using the power of magic. Since it's an unknown frontier with no model to follow at all... that’s probably it."
"...I see."
Though she didn't seem entirely convinced, Elsa nodded for the time being at Jin’s explanation.