Sang Yi is a person who is used to catching thieves, and he has a set of tracking and surveillance, so he is responsible for tracking Qin Huailiang and finding out the two people behind him.

Xu Ping returned to the restaurant and made up an excuse to take a silver collar with a slightly different color from his mother, which should be the medicinal silver that was exchanged for by Granny Hong.

Zhang Sanniang was impatient, Xu Ping didn't dare to tell her the truth of the matter, but secretly told Liu Xiaoyi to keep an eye on Granny Hong these days, and report anything wrong to his father Xu Zheng.

After arranging things properly, Xu Ping returned to Zhuangzi.

These days, alfalfa is harvested in the village, and the root stubble is set aside in time for wintering. Alfalfa is not suitable for silage, but for making hay, and to put it more professionally, it is to be conditioned. It is best to dry it semi-dry, and then store it in a proper way.

Xu Ping deliberately designed a baler to beat the recovered alfalfa into large square bales to facilitate storage and handling. The grass is beaten into dense bales, which can not only ensure stable quality, but also save space when transporting long distances. At this time, the forage collected by the imperial court was scattered, and the price of a piece of grass was as large as a stone of grain, but it was much more difficult to transport a piece of grass than a stone of grain.

Back in Zhuangzi, Xu Ping first went to the wheat field to see the alfalfa harvest.

The baler is powered by a donkey, and the principle of crank slider is used to squeeze through a fixed channel to form. When Xu Ping arrived, Xu Chang was directing people to operate three balers.

Seeing Xu Ping, Xu Chang came up to greet him and asked him, "Why is Da Lang free to come over today?" ”

Xu Ping said: "The weather has been cold recently, and the alfalfa in the field must be recovered as soon as possible. ”

"Gao Daquan and Sun Qilang are in the field without stopping for a moment, so they shouldn't be in the way."

Xu Chang said, helped the bales of straw that came down from the baler, and exclaimed: "Da Lang thought of this method is really good, the grass is pressed into large pieces like this, and it does not take up space." Otherwise, there are so many alfalfa in our village this year, even if we take it back, there will be no place to put it. ”

Xu Ping nodded, went up and touched the tightness of the bale, still sighing secretly in his heart. In the end, animal power is still incomparable with machines, a baler is driven by three donkeys, and the density of the bales is still not half of the machine bales in the previous life, so they have to be used.

After inspecting the alfalfa harvest, Xu Ping returned to his small courtyard.

Xiuxiu was doing needlework in the sunshine in the leeward part of the yard, and when she saw Xu Ping, she hurriedly got up: "The official is back, I haven't seen you these days." ”

Xu Ping asked her with a smile: "Do you want me?" ”

Xiuxiu just shook her head and didn't speak.

Letting Xiuxiu keep himself busy, Xu Ping entered the study, and then took out the silver collar he wanted back from his mother to look at it carefully. The color of this so-called medicinal silver is white, which is extremely similar to the appearance of silver, and it is also heavy in the hand.

Xu Ping still had the real silver collar in his hand, which he deliberately left, so he took it out and put it together with the medicine silver to watch it carefully. The difference between the real and the false comes out, one is that there are slight differences in color, and the other is that in order to confuse the real with the fake, the two silver collars are exactly the same, but the density of copper is smaller than that of silver, and the weight is lighter.

Xu Ping remembered that the hardness of white copper was much greater than that of silver, so he went out and asked Xiuxiu for a needle, and sure enough, there were scratches on the real silver, and it was not so obvious on the medicinal silver.

Holding this piece of medicinal silver, Xu Ping fell into deep thought. Is this really nickel cupronickel? Xu Ping is not sure, but he doesn't believe that nickel can be refined in this era. Nickel is not difficult to smelt, in fact, it is almost the same as the difficulty of iron smelting, mainly because it was difficult for the ancients to recognize the existence of this metal, and nickel is very easy to form alloys with other metals. Meteorite iron often contains nickel, so in ancient times, some meteorite iron was used as high-quality steel to make swords and swords, which are not only extremely sharp, but also do not rust, and are actually a type of stainless steel.

Or that question, if you have the ability to make nickel and white copper, why not make stainless steel? That is to say, a meteorite flying from the sky can deceive many people, and there is no danger.

There was a night of wind last night, and this morning it was already clear, and the sun was shining warmly on people. Xu Ping didn't know the essentials, held this piece of medicinal silver, lay on the desk and fell asleep unconsciously.

Feeling movement in the dream, Xu Ping woke up suddenly.

It turned out that Xiuxiu was afraid that Xu Ping would catch a cold, so she put a blanket on him.

Seeing that Xu Ping was awakened, Xiuxiu said embarrassedly: "Disturbing the officials to rest." ”

Xu Ping shook his head: "It's okay." ”

Seeing Xiuxiu holding a yellow-brown thing in her hand, Xu Ping asked her, "What is this?" ”

Xiuxiu said: "This is orpiment, I asked Su'er for it, and I can use it to correct the typographical error." ”

Xu Ping let out an "oh". Orpiment is the ancient modification liquid, and the word is used to alter if it is written wrong, and this is how the idiom of the word orpiment comes from.

Xiuxiu said again: "I originally put it on the table, but the official didn't see it, and it was about to reach your mouth when I was sleeping on my stomach." This thing is poisonous and not easy to eat, so I will never put it away again. ”

"Poisonous?"

Xu Ping asked casually.

As soon as the words came out, Xu Ping's mind flashed, and he slapped the table: "I know!" ”

This frightened Xiuxiu, patted her chest and asked Xu Ping: "What do the officials know?" This surprise scared the hell out of me! ”

Xu Ping laughed and patted Xiuxiu's shoulder: "It's not about Xiuxiu, it's an official, I have something I haven't been able to figure out, with Xiuxiu's reminder, I figured it out at once." ”

Xiuxiu asked curiously, "What is it that makes the officials so concerned?" Tell me and hear it. ”

Xu Ping shook his head with a smile: "This is not a good thing, so I can't tell you." ”

Xiuxiu made a disgusted expression: "I don't want to hear it yet!" ”

After speaking, he left the study and continued to busy himself.

Xu Ping looked at the medicinal silver in his hand over and over again, and said to himself: "I drilled the tip of the horns, and I thought it was nickel and white copper, so I couldn't figure it out." Thanks to Xiuxiu's orpiment, I remembered that there is not only one kind of white copper, this should be another, arsenic white copper, isn't it? ”

Xu Ping still had a chance glance at it when he was checking nickel and white copper in his previous life, and there was also a kind of white copper alloy in Chinese history, that is, arsenic white copper. Arsenic cupronickel is so similar to nickel cupronickel that the ancients often confused it. However, due to the toxicity of arsenic white copper and the lack of outstanding properties, the later generations basically disappeared.

When the trick of ancient Chinese monks turning stones into gold became more and more unable to deceive people, they developed this kind of thing, copper arsenic alloy. When the content of arsenic in the alloy is low, it is golden yellow, that is, the gold of the medicine. When the arsenic content exceeds 10 percent, it becomes a silvery-white color, which is the so-called medicinal silver.

The difference between medicinal gold and real gold is relatively obvious, so it has not spread, and what has always prevailed is the secret art of so-called medicinal silver. The reason why Xu Ping associated this with orpiment is because the earliest medicine used to order gold and silver is orpiment. The ingredient of orpiment is arsenic sulfide, which is generally heated into arsenic oxide, i.e., arsenic, and then reduced to arsenic with charcoal, which is combined with liquid copper to form a copper-arsenic alloy. Later, arsenic became a common substance, so it replaced the orpiment and realgar used when ordering medicinal silver, and became a secret medicine in the formula.

The general chemical reaction of this principle of atractylodes is like this, of course, the actual process depends on the specific operation method, in order to obtain arsenic white copper as white as silver.

Thinking of this, Xu Ping let out a sigh of relief.

Knowing what was going on with the alchemist's magic would make it easier to track it down. At this time, arsenic had been used in medicine, and it was sold in pharmacies. But as a strong poison, arsenic is not something that can be bought casually, and it is impossible for that gang to use it on a large scale without leaving traces.