Chapter 58: The Strange Man's Bizarre Lesson

  Song Jiuxian first took out two small firecrackers, opened one of them, lit it, and it burned out immediately. The other firecracker didn't move, so he also lit it and said, "Why can a firecracker only burn when it's opened, but not explode?"

  It is also unknown who first invented the use of gunpowder to make firecrackers, but since its appearance, it has been viewed this way, and must be wrapped in paper before ignition. When children unwrap and play with unlit firecrackers, adults do not take it seriously.

  It's normal if you don't ask, but once you ask, there must be a reason. But what is the reason? No one can answer that. Song Jiu said, "The reason is simple, it's because of too much pressure."

  Then, from the next room, he brought out an iron frame, a candle, several sheets of paper, a teacup, a kettle, two small stools, a sandbox, several pieces of iron ore, a large bellows, and a shuttlecock, one by one.

  First, twenty officials who were as nervous as if they were sitting on pins and needles were given brushes, ink, paper, and inkstones. The students were so afraid that they didn't dare to give their lessons. They had taken the emperor's seat by force and were similarly trembling with fear in their hearts. Song Jiuxiao said: "Everyone, grind your ink and listen carefully to my lesson. Take notes on important points, and ask if you don't understand."

  Then light the candle, put a piece of paper on the candle, and it will burn in the blink of an eye. "Everyone sees that it doesn't ignite immediately. Flammable materials all have an ignition point, some high and some low, but for an object to burn, there are three conditions: first, the object itself must contain combustible elements; second, there must be a combustion aid, such as air and oxygen; third, there must be an ignition source to make the object reach its ignition point. This will be discussed in more detail later, because in the mine, there will be carbon monoxide, carbon dioxide, and various alkanes, which are also known as "underground toxic gases" by miners. First, they can harm the safety of miners' lives; second, they can have some influence on the burning of fuses. Please take note."

  This is relatively simple chemistry, but everyone who heard it was stunned.

  But it is indeed necessary to understand at least a rough idea in order to successfully blast later and also reduce the mortality rate of miners.

  "This is not the first lesson to be taught, Song Jiu again used paper to fold a paper box, placed it on the iron frame, poured a little water from the kettle into the paper box, and moved the candle under the paper box. He said: "Everyone look again, the paper can't burn now, because it transmits heat to the water, so the paper never reaches its ignition point. When the water is burned dry, when can the paper be ignited? The thermal conductivity of various objects is also different. Iron conducts faster than wood. In my previous life, many soldiers wore armor into battle, and the armor was made of iron, which had a good heat conduction effect, making it hotter in summer and colder in winter. Therefore, the northern winters and southern summers became the most feared times and places for the soldiers of my dynasty. This is not what you should be concerned about now, I just want to talk about this water. Everyone sees that the water is boiling immediately, but where did the water go? It turned into steam, water vapor. Water has three forms: solid ice, liquid water, and gaseous water vapor. Our sky also has a lot of water vapor, accumulating to a certain extent, when these small water droplets accumulate on the rising air flow, it will rain in summer, if the sky is very cold, it will condense into solids during the falling process, which is snow."

  "Song Jiu, are you saying there are many things in the sky?" Zhao Pu couldn't help but ask.

  "Director Zhao is wise and immediately understood that this sky is not a vacuum, it also has many substances, because it is formed by gas, we can't see or touch it. Next, let's look at another experiment," Song Jiou poured water into the teacup, and the water flowed out: "Why did it flow out? Because of gravity."

  Then he filled the teacup with water, covered it with paper, carefully tilted it horizontally and poured it down. He released his hand covering the paper, and one piece of paper covered it, without a single drop of water leaking out. This was very strange, and everyone discussed it in an uproar.

  "The real reason is simple, the air is not empty, there are various substances, it will produce all kinds of pressure, forming pressure on paper, so a thin sheet of paper can hold up a cup of water, offsetting the unit weight of the earth." Song Jiuzhong and twenty other officials remembered this, and did another experiment, placing a board on the sand, saying: "You see, the more stones are pressed, the greater the pressure, the deeper it will sink. This is called pressure, what is meant by pressure strength is that the pressure borne by unit area is different."

  Another experiment was done, with the four legs of a bench facing down and pressing on stones, while another bench was placed face down and feet up, holding the same stones.

  These simple experiments allow everyone to have a preliminary understanding of stress, pressure and combustion. Song Jiuxiao then did another experiment, taking over the ball, Tang Dynasty was hitting the ball, that is, polo, Song Dynasty lacked horses, played on foot, Cuju, which is kicking football, just with different rules, but the football made is quite standard, some good football elasticity is not much worse than later generations. It's just that the cost is relatively expensive.

  The air pipe inflated with the bellows was pumped in, and finally, it burst. Song Jiu said: "Why did it explode? It's because too much air was pumped into it, the pressure became greater and greater, and the unit pressure also became greater and greater. This pressure exceeded the limit that the leather could withstand, and finally burst."

  "Now, let's talk about firecrackers. Why is it that when they're sealed, they explode, but when they're not sealed, they just burn? It's precisely because of this pressure factor. When they don't encounter fire, everything is fine, but as soon as they do, they can instantly form high-temperature and high-pressure gases, causing the surrounding materials that bind them to be subjected to intense impact, leading to deformation or shattering. If there's no binding, the pressure quickly disperses and won't form a powerful explosive force, so it can only burn but not explode.

  That day, I conducted an experiment, letting that box of gunpowder blow up a city wall. In reality, if conditions permit, its power would be even greater, to the point where just that one box of gunpowder could shatter a small mountain. Of course, this is impossible.

  For example," Song Ji pushed his teacup on the table: "From a mechanical perspective, due to inertial forces, the teacup can keep moving indefinitely, but in reality, it only moves a little bit. Why? Because there's gravity, frictional force, and other external forces that cause the teacup to ultimately stop.

  Gunpowder is the same way. We can only achieve theoretical sealing, and various objective factors will make its explosive power decrease infinitely." He wrote down an equation, which was the explosive yield of that box of gunpowder. But he didn't explain it in detail; explaining it would be too troublesome, and even if he did, no one would understand it. It could only be understood by about twenty officials.

  This is about the explosion of gunpowder, precautions and so on. While lecturing, experiments were being conducted, strange knowledge, strange lectures, but everyone listened to it and enjoyed it.

  After finishing one lesson, Song Jiu said: "Everyone, please ask questions. Each person must ask more than three questions."

  These officials and craftsmen were also educated, in the traditional form of education, but it is unknown whether they listened or understood. Although they made records, not one person asked questions, so Song Ji forced them to ask questions. Only by asking can you deepen your impression. A student who does not know how to ask questions will find it very difficult to achieve good results. A teacher who does not like students to ask questions will also find it very difficult to be a good teacher.

  They started hesitantly at first, but Song Jiu urged them to ask questions, so they asked, and the more they asked, the more enthusiastic they became. Even Zhao Kuangyin eventually asked a few questions.

  The sky was darkening, and Song Jiu finally stopped.

  Everyone walked out, and the big iron gate was locked again. There were still several soldiers standing guard at the door.

  Many ministers were discussing in low voices, it was no longer so mysterious, felt like they understood a lot more, and were excited.

  This was the effect that Song Jiuxin had hoped to see, his own promotion was useless, and it needed the imperial court to promote from top to bottom. Just like cotton planting, it was very slow at first, but after Zhu Yuanzhang issued an edict, the whole country started planting cotton, and suddenly cotton was everywhere.

  I don't know if at this time cotton seeds can be found from Xiyu and Lingnan and planted successfully.

  Thinking too much, if you want to live, there's still a lot of work to do, textile machine! Do you still want to live? First, deal with steel.

  After seeing Zhao Kuangyin off, Song Jiu scolded twenty-one students.

  The monarch and his ministers now have some misunderstandings about Song Ji, which is inevitable. After all, there is a gap of over 1,000 years, and there are huge differences in understanding. However, Song Ji's educational approach is very advanced, with more emphasis on moral education. Why do children from poor families have a higher probability of becoming corrupt officials? In the past, they were too poor, and their ability to resist the temptation of wealth and power was relatively weak. Some teachers taught students that wealth and power are like fierce beasts, and the country also did so, promoting the spirit of hermits, who are noble and consider wealth and power as fleeting clouds. But how many people can actually achieve this?

  So Song Jiuxu went against the grain and did it his way, filling in the gaps rather than blocking them. Don't be afraid of wealth and status, they're not that bad, but one must obtain them within the bounds of propriety. As Master Kong said, give me money and I'll even carry a cow whip, for labor is not shameful.

  Of course, these views must have caused serious conflicts with the two doctors, resulting in a small quarrel every three days and a big one every five days.

  Back home, there is still one important thing to do.

  Zhang's old woman sat under the pagoda tree with two children, waiting for him to come back, and the elder sister personally came over to cook.

  An old woman came to the Song family with a worried look, but in fact, Song Jiu was very depressed. The old woman wanted to sweep the floor, but where would she let her sweep? Song Jiu taught practical lessons and also cultivated his students' hands-on ability, and he didn't want to spoil their bodies either. The students took turns cleaning the courtyard, the front and back of the house, tidying up some tools, pens, ink, paper, and inkstones, and even making tea was done by themselves in the kitchen. Firewood was bought back, one, two, three moved to the kitchen. As for the rest, either washing clothes, which Song Jiu didn't want her to do, or cooking, the old woman's situation wasn't good, her son had died in battle, and Bei Han was so poor, where would there be any compensation? What delicious food could she make?

  The old lady is a laborer, not letting her do anything to support herself is too difficult. Song Jiuren said helplessly, "Old lady, why don't you learn some needlework and earn some small money for your grandchildren's future?" At that time, there weren't many ready-made clothes for sale, and needlework was a huge industry. Only then did he send the old woman away.

  But there was one thing that gave Song Ji a headache. The old woman's grandson was still okay, he was just less talkative. But the granddaughter didn't know where she learned it from, and as soon as she saw Song Ji, she would shout "Dad!" The old woman saw that Song Ji wasn't mean, so in the end, she didn't stop her either. Song Ji wouldn't let her call him that, but the little girl would just cry. Song Ji was at his wit's end - he wasn't even married yet, and every day a little girl followed him around calling him "Dad!"

  Seeing Song Jiu coming back, he came again and warmly pounced over: "Dad."

  Song Jiuying was not, nor was she not. The elder sister sat on the side, crying and laughing were not. She patted the little girl's head and walked in front of the elder sister: "Sister, you've come, where's the wine?"

  "Xiao Jiu, I've come to ask you for a favor."

  "Sister, you're killing me, how dare I be your suitor."

  "You're a big shot, and Big Sister is making demands too."

  "Sister, don't say it again, if I hear it once more, I'll collapse."

  "Xiao Jiu, there are customers looking for that fruit dish, teach me how it's done."

  Song Jiu nervously pulled his elder sister aside and whispered: "Elder sister, how much does it cost to make one of those fruits?"

  "I don't know."

  "The cheaper ones are less than twenty cents, and some are even only ten cents. The more expensive ones can be thirty or forty cents. But the sugar coating is expensive, otherwise it would cost even less. I wonder how much one will sell for in the future?"

  "What's that thing for?"

  "It's not me selling, it's Yu Ping selling later."

  "Jade lotus can't be sold."

  "Don't worry about Yu Ping's affairs. A real man should have achievements, why worry about not having a wife? I'm telling you, that fruit, the lower quality ones will be sold for 500 coins, and the higher quality ones, I think I'll sell them for one tael of silver."

  "You're going to die making this dirty money!"

  "Can poor people afford to buy it even if it's sold cheaply for 50 cents? No, they still can't afford it. It can't be sold just anywhere; once it's sold in your small wine shop, its value will plummet. Don't worry with your sister's husband, you'll have your own business later. I won't say any more, I'm going to eat first, and after eating, there's still work to do." Song Ji hastily called the four painters to come and eat, after eating, they had to do a serious task - paste the paintings!