Solving the Mystery

A quarter of an hour later, two yamen runners brought the items in and set them out in the hall.

The three officials glanced over the implements, then turned to Xu Qi'an.

Prefect Chen said gravely, "Everything you asked for is here. You must give me a satisfactory answer."

His attitude had changed somewhat.

Over that quarter of an hour, the Principal Fourth Rank official had racked his brains for a long time and had to admit that Xu Qi'an's deduction made a great deal of sense. Yet many questions remained unanswered. For instance, the tax silver had indeed fallen into the river.

He could not fathom what hidden truth lay behind it.

"If I help you solve this case, sir, could you submit a memorial to the Sage and absolve my Xu Household of its crimes?"

Great Feng placed great importance on inheritance between father and son. A son could bear his father's punishment, but he could also atone for his father through meritorious service.

"Naturally." Prefect Chen nodded.

Xu Qi'an nodded and squatted before the implements. The props laid out in front of him were a candle, salt, a porcelain cup, and iron wire.

What he needed to do was simple, using high school chemistry: extract metallic sodium.

In ancient times, extracting it would have been utterly impossible, with two major obstacles: electricity and sodium chloride's melting point.

But in this world, Xu Qi'an knew of a profession that could do it.

The sixth rank among the Directorate of Astronomy's sorcerers: Alchemy Master!

Alchemy Master was a household name in Great Feng. Their inventions and creations had long since become part of ordinary people's lives.

Xu Qi'an wasn't certain that the tax silver which exploded was metallic sodium. That didn't matter. What mattered was opening up a line of thought to explain the explosion.

When solving a case, bold hypotheses and rigorous reasoning were essential preliminary work. Only afterward did one verify them and collect evidence.

In his previous life, he had encountered a murder case that remained vivid in his memory. The criminal investigators had stayed up all night, letting their imaginations roam based on the clues and proposing several possible sequences of events, then collecting evidence on that basis.

Then they had overturned every one of them and reasoned everything out again.

The tax silver might not have been metallic sodium either. In any case, an Alchemy Master could have done this.

That was enough.

Putting the officials back on the right track was what he needed to do.

Once they were headed in the right direction, they could follow the vine to find the melon, and uncovering the mastermind wouldn't be difficult.

If they kept struggling under the assumption that a monster was causing trouble, they would never solve the case. Even if they did solve it someday, the imperial court would already have: sent him away, a thousand miles away!

He dissolved coarse salt in water, stirred it, then covered the cup's mouth with raw xuan paper and slowly poured the saltwater through.

After filtering it, he set the porcelain cup over the candle to heat and stirred constantly with a bamboo skewer.

Before long, the saltwater in the cup had evaporated, leaving crystals of sodium chloride.

Essentially, he had further purified the salt.

Prefect Chen, the middle-aged man, and the exceptionally beautiful girl in the yellow skirt stood around him, watching intently.

Xu Qi'an looked up and grinned at the girl in yellow. "You're a disciple of the Directorate of Astronomy, aren't you, my lady?"

He had noticed the Feng Shui Compass at her waist. No one but a disciple of the Directorate of Astronomy knew how to use one.

"Mm-hm," the girl in yellow replied with a grin. "My master is the Superintendent of the Directorate of Astronomy."

Her delicate, radiant oval face was like a peeled egg, fair and flawless.

A disciple of the Superintendent. Her chest and all that doesn't matter. Xu Qi'an spoke gently. "Sorry to trouble you, big sister, but could you melt these crystals for me?"

Sodium chloride's melting point was around eight hundred degrees Celsius.

The girl in yellow pursed her little lips. "Only Alchemy Masters can control fire. I'm just a Feng Shui Master."

"But my master gave me a magic artifact," she added, changing tack. She took the Feng Shui Compass from her waist, adjusted it a few times with her slender fingers, and fed Qi into it. The character for "fire" lit up.

"Stand back!"

Xu Qi'an immediately retreated. The next moment, a tongue of flame blindingly bright shot out and engulfed the porcelain cup.

"Stop!" Xu Qi'an immediately called out. He quickly inserted two pieces of iron wire into the porcelain cup and asked, "Can you pass an electric current through it? No, lightning magic! Be careful to control the voltage. Hmm, this step is very difficult. It might take many failed attempts."

She turned the Feng Shui Compass and used a slender finger to light up the character for "lightning." Several arcs of electricity flashed through the air and struck the wires.

"Sizzle." The molten sodium chloride underwent a violent chemical reaction.

"Stop!"

Xu Qi'an held his breath and leaned over the cup to look. A silvery, shiny lump of metal had formed, with some unconverted crystals and impurities around its edges.

It actually worked on the first try. The voltage was just right. Xu Qi'an was delighted.

Producing metallic sodium through electrolysis required a voltage of around six to fifteen volts. He had mentally prepared himself to fail repeatedly.

Unexpectedly, he had been possessed by the European Emperor and succeeded on his first try.

Prefect Chen and the middle-aged man eagerly leaned over for a look. In the cup was a lump of silver-colored metal that, at first glance, looked remarkably like silver.

Prefect Chen's pupils contracted, and he was deeply shaken.

Li Yuchun clenched his fists tightly and stared blankly at the silver-colored lump, as though a bolt of lightning had struck his mind and cleaved through all the fog.

"Please look, sirs." Xu Qi'an poured out the metallic sodium, wrapped it in xuan paper, and weighed it in his hand.

"This stuff is much, much lighter than silver, but it looks extremely similar. If someone used it to impersonate silver, couldn't they pass the fake off as the real thing? You can all weigh it in your hands as well."

He handed the metallic sodium to Prefect Chen. By now, its luster was gradually growing dull, making it look almost identical to silver.

The middle-aged man took it and weighed it in his hand. His eyes shone as he said repeatedly, "It really is much lighter. If this was what they were transporting, then it all makes sense. Miss Caiwei, try it."

The girl in yellow took it and weighed it, then stared at Xu Qi'an strangely. "You... you're an Alchemy Master?"

No, I'm not. I'm just a porter of chemistry.

A scholar's mind was more agile, after all. Once his surprise had passed, Prefect Chen suddenly shook his head and said gravely, "No, that's not right. Even if the silver was replaced with this, what about the explosion? If there wasn't a monster hiding in the river, why would the fake silver explode when it entered the water?"

Xu Qi'an didn't answer. He reached out, took the metallic sodium, walked over to the desk, and dropped it into the brush-washing jar.

A fierce blaze flared up, and thick smoke billowed.

"Boom!"

The metallic sodium reacted violently in the water, and a web of fine cracks spread across the brush-washing jar.

"Th-this..." Prefect Chen was dumbstruck.

"This fake silver explodes when it comes into contact with water. That explains why there was such a violent explosion after the silver fell in," Xu Qi'an explained.

The middle-aged man murmured, "We were misled from the very beginning. The mastermind used the explosion and the demonic wind to make us think a monster was responsible, directing our investigation toward tracking it down and capturing it."

"No wonder even the Imperial Astronomical Bureau's Qi-Observing Technique couldn't detect a monster."

Xu Qi'an added, "After the tax silver fell into the water, the soldiers only recovered a little over a thousand taels of silver. If I'm not mistaken, that silver was all laid on top to deceive people."

Everything fit together perfectly. Every anomaly was accounted for.

"Xu Qi'an!" The middle-aged man's eyes were full of approval. "Good, very good."

His brows suddenly furrowed, and his gaze fixed on Xu Qi'an's crooked collar. As Li Yuchun patted him on the shoulder, he pulled the collar straight.

Xu Qi'an was flattered. This official appreciated him so much.

Prefect Chen frowned. "Since the silver was fake, where did the real silver go?"

Hearing this, the girl in yellow also grew grave. "The tax silver changed hands at every level after leaving the treasury for the capital. If blame is to be assigned, a great many officials will have to be imprisoned. Recovering the silver will be no easier than fishing a needle out of the sea. Besides, this matter has already exceeded our authority. We must report it to His Majesty."

Prefect Chen nodded. That was precisely what he meant.

The middle-aged man had a different view. His voice was low. "The tax silver was escorted all the way to the capital and changed hands at every level. If it were fake, it should have been discovered long ago. The only possibility is that it was switched recently."

Prefect Chen's eyes lit up. That greatly narrowed the scope of the investigation.

"Someone, prepare my sedan! Quickly! I must go out." Prefect Chen rushed out of the inner hall.

The middle-aged man followed close behind.

Xu Qi'an hurriedly called out, "Prefect, please don't forget your promise to me!"

Ha, metallic sodium burns when it comes into contact with water and makes a roaring sound. What would happen if hundreds or thousands of jin of metallic sodium were thrown into a river? I don't think it would be any less powerful than explosives.