I understood He Xiaoyu's point. It was like placing a magnificent classic novel before someone who disliked reading; it would be useless. If someone disliked going out, giving them a Rolls-Royce would bring no joy. I was precisely that kind of person. I preferred staying home to conduct experiments or read during my days off, and I rarely went out unless it was for work.
Therefore, when the old man spoke of something useful, it was a broad interpretation. If I were to say something was useful later, and he, from his perspective, considered it useless, then this test would not be passed.
Unless the thing was something everyone needed, like food? Air? Sunlight?
Thinking of this, I suddenly noticed something. Wasn't there flowing water here? My eyes lit up, and a proud smile appeared. "Sir, I understand. The useful thing you're referring to should be water! Because everything in this world needs food, air, sunlight, and water. This place has no light, the air is especially thin, and there's no food. It must be water!"
"Hahaha! I didn't expect you to discover it even like this. He Sheng, you are indeed clever. Well, I'll tell you some good news. The last trial is ahead. I hope you can pass it smoothly. I have high hopes for you. Have you noticed? The door ahead has already opened!"
Accompanied by tremors and loud noises, He Xiaoyu and I witnessed the stone door before us slowly opening. We both stared intently ahead. When the stone door had opened to a certain width, He Xiaoyu, as if to test the way for me, stepped forward.
I quickly followed behind her, step by step. After passing through the gate, I found this secret chamber to be several times larger than the previous ones. It seemed this was indeed the final trial. Didn't I hear the sound of flowing water earlier? It turned out that water was flowing here. I discovered that the walls were transparent, and water was gurgling through them, its source unknown.
At this moment, the old man seemed to have read my mind and posed a question: "Alright, the final trial. He Sheng, listen. You can probably see the flowing water now. What you need to explain to me is where this water is flowing from, from what era it started flowing like this, and what components are mixed in the water!"
What? The first question was manageable, but the latter two, without laboratory analysis, were impossible to answer!
I coughed. This was truly testing me. Fortunately, I had brought the Wuying Reflection Tube and the Bamboo Leaf Extractor. Although I didn't know if they would be effective, I had to try. I couldn't fail this final trial.
Upon observation, I found it was completely useless. These tools were not suited for this situation. Unless Zhang Keying and Xie Chuchu were here with some precise instruments, these forensic methods would be ineffective.
But here, the old man wanted me to use forensic methods to solve the puzzle. If I couldn't complete it, the clan leader and the others definitely wouldn't let me leave!
What should I do? How could I possibly answer these questions!
I don't know how many times I repeated "What should I do?" in my mind, but still, no solution came to me. This wasn't a matter of wanting to or not; under the current circumstances, without technical support, everything was just talk.
Take the Bamboo Leaf Reflector, for instance. It can indeed test for poison, but to specifically analyze the components of the poison, it requires laboratory testing. And the old man's question was about the components mixed in the water. How could this possibly be verified?!
Perhaps seeing my distress, He Xiaoyu said, "Young Master, I have a way!"
Hearing her, I looked at her in surprise. He Xiaoyu ignored me and, at some point, produced a hammer and smashed it hard against the wall. The gurgling water flowed out within a minute. "What are you doing!"
"Helping you! Didn't you say you couldn't find a way?"
"But what's the use of smashing it? We can't possibly analyze the components of this water!"
"No, try it. Squat down first!"
Although I was confused, I squatted down as He Xiaoyu instructed. Facing the flowing water, I used the Bamboo Leaf Extractor to draw some of it. At the same time, I sniffed the air and detected a strange odor.
Hmm? He Xiaoyu was squatting beside me, and both our attentions were immediately drawn to the liquid. I swirled it in the Bamboo Leaf Extractor. At this moment, He Xiaoyu snatched my tool and attached the Wuying Reflection Tube to a notch on it!
I was almost startled. What was this?
"Bamboo Leaf Reflection Tube!" He Xiaoyu exclaimed excitedly. I felt the name was quite fitting, but what use could these two combined have?
I really wanted to complain, but before I could, the head of the reflection tube suddenly flashed with a strange light, slowly revealing some crooked marks on the wall.
I walked over slowly. It was the first time I had seen these two forensic tools react like this. If it weren't for He Xiaoyu, I probably wouldn't have known.
This situation was as if some secret was hidden within, and I needed someone to hand me a key to unlock this long-sealed chain.
But the lock truly opened before my eyes. The problem was, what did the text revealed on the wall mean?
"This is Song Dynasty text, isn't it? Song script, it's quite similar to modern traditional characters, isn't it? This means the 'grey blowing method'."
"Grey blowing method?" I looked at He Xiaoyu before me, puzzled. I used to think my knowledge was quite extensive, but now I couldn't find any connection. He Xiaoyu stepped closer, examining the wall very seriously. "If I'm not mistaken, it should refer to black ore (Argentiferous galena). I recall that chemistry was a subject with significant achievements in Song Dynasty science, especially in metallurgy. Zhao Yanwei of the Southern Song Dynasty recorded that after obtaining Argentiferous galena, it was 'crushed daily and ground again,' then washed. 'The black one is silver. It was kneaded with flour and lead, then heated into large sheets. It was then sent to the official treasury. After two or three days, it was re-fired into fine silver.' This was the 'grey blowing method' of refining silver, which involved melting silver into lead, then oxidizing the lead, and using furnace ash to separate the silver."