Al shook his head, "Let's stop the experiment, I think something is wrong with our research direction." ”

"Perseverance is important, but if we go in the wrong direction, it will only be the opposite of the truth, pushing us further away from the truth. ”

"Nightingale, smell it again, and think about what it is? ”

Nightingale sat directly on the ground and propped up her little head in thought. And pandan lay in her arms and pretended to sleep, trying to recover her energy as much as possible.

Al also wondered as much as he could, "What is it? something that is unique to human beings and not found in nature?"

Just as he was thinking, the efficient dark elves had collected a few soil samples from all over the world and sent them to the El.

And Al also began to number these samples non-stop, compare, and test their differences in various ways.

For example, these parts of soil are put into water separately and stirred vigorously with wooden sticks to observe the degree and speed of their dissolution in water, and the phenomenon of soil stratification and sedimentation.

Or grill the soil over a fire and observe how it changes color at elevated temperatures and if it smells different.

"It smells like it's all burnt. ", Al muttered to himself, as he pulled the nightingale over and continued to act as a human probe.

"That smell seems to be a little more pronounced just now. Sniffing carefully, Nightingale said with some uncertainty.

"Obviously?", Al said excitedly, "then this mysterious substance may be the commonality of these samples, and perhaps the key factor in the growth of fluorescent wheat." ”

"And the smell has become more pronounced, indicating that the substance may be volatile when heated. ”

With this in mind, Al used the stick to write a few lines on the ground: what is unique to human beings and not found in nature.

Here are a few items: smelting utensils, dyed clothing, spices of all kinds, food, ...... There are more than a dozen sprinkles.

Due to the lack of productivity levels, human beings in this world are certainly unable to produce man-made fibers, plastics, and other products that are not available in nature like humans on earth. But in terms of smell, several flavors come together to create odors that are not found in nature.

But the smell certainly won't be much.

Al made up his mind to use a "stupid method", the elimination method, to determine the smell. Unfortunately, since it is now underground, there is no physical object to conduct the experiment, so Al can only use oral methods to describe it.

"First of all, is that smell fragrant or stinky, is there a pungent smell?" Al asked.

Nightingale thought carefully: "It seems to stink a little? I'm not sure, it's a little pungent, I kind of remember, how many times did I sneeze when I smelled it?"

It's a bit smelly and pungent. Al wrote the words on the ground and rescratched them twice.

Following these clues, Al ruled out some of the options and began to describe them to the nightingale.

Sometimes there were more words on the ground, sometimes there were fewer words, but when the light of the fireflies dimmed again, there were finally only three words left on the ground, and after a while they finally became one again.

Al stared at the writing on the ground in a daze, as if he couldn't recognize the words anymore, even though they were written by his own hand.

Stinky tofu suspected to have been mixed with garlic.

This was an answer that Al had never thought of before, and it was the answer that he and Nightingale had spent a long time trying to come up with.

The nightingale came over to take a look, and suddenly shouted: "Yes, yes, it seems to be this thing called stinky tofu, and the person who sold it at the time said that it smelled bad and tasted delicious, but unfortunately no one around dared to try it." ”

Saying that, Nightingale sighed, "At that time, I wanted to try it, but unfortunately I really didn't have the money." ”

Al began to pace in circles, "Garlic, stinky tofu, is it possible that this fluorescent wheat still likes to eat stinky tofu?"

"It's impossible!"

He racked his brains to gather the knowledge in his mind, not only the knowledge of this world, not only the knowledge of this world, but also the knowledge of the earth, which had become faintly blurred.

In the end, it was junior high school geography that saved him, as the highest achievement of his ten years of hard study and sea study: Al once served as a geography class representative for a year.

And he remembered that there was such a knowledge point, which was talked about by the geography teacher at that time as an interesting talk: phosphate rock, with a pungent smell, similar to garlic, and slightly smelly.

Phosphorus, it turned out to be phosphorus! Al slapped his head a few times, and he didn't know how many times he scolded himself, "Idiot!"

"Why does this fluorescent wheat glow? It's because it contains phosphorus. Such an obvious feature, because I just thought that this was a magical world, I didn't even consider it at all. ”

The nightingale hurriedly ran over and grabbed Al, "Hey, don't shoot, it's really stupid to shoot again." She looked at Al worriedly and comforted: "Don't be too anxious, it's only been a few days, and we still have some food reserves." ”

"I'm in a hurry, I'm happy!", Al turned around and hugged the nightingale, and said hoarsely, "I found it, nightingale, I found it." ”

"Really?" Nightingale confirmed, grabbing Al happily, unaware of how much he had been taken advantage of.

When her mood calmed down, she found that Al was still lying on top of her, and she was ashamed and annoyed that she punched Al to the point that she was holding her head and begging for mercy.

"You bastard, don't you verify it quickly!, if you're wrong, you'll be skinned!", the nightingale roared.

Her scolding calmed Al down, and his heart shook.

Phosphorus is soluble and flammable, and will emit phosphorescence in the dark. Almost all the strange stories that resemble ghost fires on Earth are due to the phosphorus content in biogas.

"But it doesn't make sense, why phosphorus? Is there a high phosphorus content in this land? There is phosphate rock buried underneath?"

Al and Nightingale dug several large pits of several meters, but did not see a single piece of phosphate rock.

"Why is there such a high phosphorus content in this soil if there is no phosphate ore?" thought to Al, puzzled.

Perhaps it was the solution to the phosphorus puzzle that made Al think a lot more open. He glanced around and saw the moonlight fish in the dark river that was like a big snake, gathering together and shining slightly, and suddenly thought, "Why can this fish also glow?"

Thinking like this, he hurriedly grabbed the nightingale: "You dark elves have drunk the river water for so long, is there nothing abnormal?"

"Anomalous? ", said the nightingale puzzled.

"Yes, it's okay for you to eat fluorescent wheat for so long. Phosphorus is highly poisonous, could it be that the dark elves have a special physique and are invulnerable to all kinds of poisons?" Al thought enviously.

Al plunged into the water again, disturbing the school of moonlight fish that were like Bai Lian. As if frightened, the serpent suddenly dispersed.

Al quickly caught one, and the small fish kept fluttering in his hand, and it was difficult to catch the slippery ones.

Al brought the moonfish to the nightingale's mouth and "ate it." Al said unquestioningly.