Song Jiu first took out two small firecrackers, dismantled one, and lit it. Once it was burned, it disappeared. The other firecracker did not move, and also lit it, saying: "Why can it only burn when it is demolished, but not blown up?"

I don’t know who invented the use of gunpowder as firecrackers first, but this is what I saw since it appeared. It must be wrapped in paper before it can be set off. If a child is opened and opened and put it away, the adults will not think seriously.

It is normal not to ask. Once you ask, there is always a reason, but no one can answer the reason. Song Jiu said again: "The reason is very simple, it is the pressure."

Then he took out an iron rack, a candle, a few pieces of paper, a teacup, a kettle, two small stools, a sandbox, a few pieces of iron ore, a large bellows, and a ball of rice were placed one by one.

First, he distributed pens, ink, paper and inkstone to twenty officials who were sitting on pins and needles. The students were so scared that they dared not give lectures. They snatched the emperor's position and were also very trembling and extremely scared. Song Jiu said: "Everyone grinds ink, listen carefully to my teachings, make records of important places, and have to ask if you don't understand."

Then lit the candle, put a piece of paper on the candle, and burned it in a blink of an eye, saying, "You all think that it is not ignited immediately. Flammable materials have a ignition point, some are high and some are low. But there must be three conditions for the object to burn. One is that the object itself contains elements that can burn, the second is that it must have a ignition material, such as air and oxygen, and the third is that there must be a ignition source to make the object reach the ignition point. This will be discussed in detail later, because there will be carbon monoxide, carbon dioxide and various alkanes underground in the mine, which is the underground poison gas mentioned in the miner's mouth. First, they will endanger the life safety of miners, and second, they will have some impact on the combustion of leads. Please record it."

This is a relatively simple chemistry, but everyone was stunned when they heard it.

But it does need to understand at least one approximation before it can successfully blast and reduce the life and death rate of miners.

This is not the first lesson to be taught. Song Jiu folded a paper box with paper and placed it on an iron rack. He poured a little water from the kettle into the paper box, moved the candle to the bottom of the paper box, and said, "Look at it again, the paper cannot burn because it transfers the heat to the water, so the paper has never reached the ignition point. When will the water be dried and when can the paper be burned. The heat transfer performance of each object is different. I spread faster than wood. I put more armor on the soldiers. The armor is made of iron, and the heat transfer effect is good, it is hotter when it is hot, and it is colder when it is cold. Therefore, the north is in the north.

The winter and the summer in the south have become the time and place that our soldiers fear the most. This is not your concern for the time being. I will only talk about this water. Did you see it? The water boils immediately, but where did this water go? It turns into water vapor. Water has three forms: solid is ice, liquid is water, and gas is water vapor. There are many water vapor in our sky, and it accumulates to a certain extent. When these small water droplets accumulate until the rising air current cannot be supported, it will rain in summer. If it is very cold, it condenses into solids during the falling process, and it will fall snow."

"Song Jiu, are you saying there are a lot of things in the sky?" Zhao Pu couldn't help asking.

"Zhao Xianggong Yingming, I immediately heard that this sky is not vacuum, it also has many substances, because it is formed in gaseous state, we can't see or touch it. Next, let's see and see an experiment," Song Jiu poured the teacup full of water, and the water flowed down as soon as he tilted: "Why does it flow down? Because of gravity."

Then I filled the teacup with water, covered it with paper, tilted it carefully, fell down horizontally, let go of the hand covering the paper, covered it with a piece of paper, and the water didn't leak. This was very strange, and I talked about it all.

"The actual reason is very simple. The air is not empty. There are various substances, and it will produce various pressures, forming pressure on the paper. So a piece of tissue paper holds a cup of water, offsetting the unit gravity of the earth." Twenty officials including Song Jiu remembered it and conducted another experiment. They placed the bench on the sand and said, "Look, the more stones you press, the greater the pressure, the deeper the sinking. This is called pressure, and what is pressure, it means that the different pressure per unit area is under."

Another experiment was conducted, putting the four legs of the bench down, pressing the stone, and putting the same stone with the other bench facing down and feet up.

These simple experiments allow everyone to have a preliminary understanding of pressure, pressure and combustion. Song Jiu then did another experiment and brought Ju ball over. The Tang Dynasty was hitting Ju, which is polo, and the Song Dynasty lacked horses and played step-by-step, Cuju, that is, playing football. The rules were different, but the football was very standard, and some good footballs were not much less elastic than football in later generations. The cost was relatively expensive.

He used the air pipe input from the bellows to invigorate it, and finally it burst and exploded. Song Jiu said: "Why does it explode? It is precisely because it transports more air into it, the pressure becomes greater and greater, and the unit pressure becomes greater and greater. This pressure exceeds the limit of the leather and finally explodes."

"Let's talk about firecrackers, why does it blow when sealing, and does not burn if it is not sealed? It is precisely this pressure factor. It is safe when it does not encounter fire. When it encounters fire, it can form high-temperature and high-pressure gas in an instant, causing the surrounding substances that bind it to be strongly impacted, resulting in deformation or fragmentation. Without binding, the pressure will quickly dissipate and will not form a very powerful pressure. It can only burn but not explode. That day I did an experiment and let that box of gunpowder blow up the city wall. In fact, if conditions allow, its power will be greater, and even that box of gunpowder can explode a hill. Of course, this is impossible. For example, this," Song Jiu put the tea cup.

Pushing on the table: "From a mechanical point of view, because of the inertia of force, the teacup can move all the time. In fact, it only moves a little bit. Why, it has gravity, friction, resistance, etc., external forces, which finally stop the teacup. The same is true for gunpowder. We can only implement theoretical sealing. Various objective factors will make its explosion power infinitely decrease." As he said that, he wrote a set of formulas, that is, the explosion equivalent of the box of gunpowder. But without detailed explanation, this explanation will be very troublesome, and no one can understand it after the explanation. It can only make twenty officials understand it.

This is where the cause of the explosion of gunpowder, precautions, etc. were discussed while doing experiments, strange knowledge, and strange lectures, but everyone actually listened and listened with relish.

After the class was finished, Song Jiu said, "Everyone, please ask questions. One person must ask more than three questions."

These officials and craftsmen are also educated, and they are all in traditional forms of education. They don’t know whether they have heard or not. Although they have recorded the records, no one asked them. Therefore, Song Jiu forced them to ask questions. Only by asking questions can they deepen their impression. A student can’t ask questions, but it is difficult for this student to have good grades. If a teacher doesn’t like students to ask questions, it is also difficult for this teacher to be a good teacher.

He started to be shy, but Song Jiu forced them to ask, and he had to ask, and the more he asked, he became more and more enthusiastic. Even Zhao Kuangyin asked a few questions in the end.

It was dusk, and Song Jiu stopped.

When they all walked out, the big iron gate locked up again, and there were still a few soldiers standing guard at the door.

Many ministers were talking down and talking, but they were no longer so mysterious. I felt that I understood a lot and was excited.

This effect was what Song Jiu wanted to see most. It was useless to promote it himself, and the court had to promote it from top to bottom. Just like cotton planting, it was always very slow. Zhu Yuanzhang issued an edict to plant cotton nationwide, and cotton was suddenly available across the country.

I wonder if I can find cotton seeds from the Western Regions and Lingnan at this time, so I can plant them alive?

I have been thinking too much. If I have a planting life, I still have to do it. Textile Machine! Should I still live? Let’s get the steel first.

After sending Zhao Kuangyin and his party away, Song Jiu scolded twenty-one students.

The king and his ministers now have some misunderstandings about Song Jiu. This is impossible. The gap is more than a thousand years, and there is a big gap in understanding. However, Song Jiu's education method is very advanced and he attaches more importance to moral education. Why is the chance of children from poor families becoming corrupt officials? They were too poor before, and their ability to resist the temptation of wealth and honor was relatively weak. Some teachers teach their students like a flood and beast, and the same is true for the country. They praise hermits. The spirit of hermits is noble, and wealth and power are regarded as clouds, but how many people can do it?

So Song Jiu went against the rules. It was better to lose things than to fill in the block. Don’t be afraid of it. Wealth is not that evil, but we must seek wealth within the scope of the rules. Just as the Master said, as long as you give me money, even if you let me take a bull whip, the income from labor is not ugly.

Of course, these views must have had a serious conflict with the two doctors, and there was a small quarrel every three days and a big quarrel every five days.

When you get home, there is another important thing to do.

The old woman in Zhang family sat under the locust tree with her two children, waiting for him to come back with a eager look, and the elder sister came over to cook the meal herself.

The old woman came to the Song family uneasy. In fact, Song Jiu was very depressed. The old woman wanted to sweep the floor, so where did she let her clean it? Song Jiu taught practical classes and also cultivated the students' hands-on ability, and did not want to make them spoiled. The students took turns cleaning. In front and behind the yard, some equipment, pens, ink, paper and inkstone, miscellaneous items in the school hall, and even let them go to the kitchen to burn tea. They bought the firewood and moved it to the kitchen room one, two or three. The rest of the matter was either washing clothes or clothes Song Jiu didn't want her to wash, or cooking. The old man was not in a good condition. Although his son died in battle, he died of a soldier. The Northern Han was so poor, where would he have a pension? What delicious food can she make?

But the old man is a working people, so it is so uncomfortable to not let her do things and raise them? Song Jiu had no choice but to say, "My mother, you should learn needlework and make a little money and think about your grandchildren's future." At this time, there were not many ready-made clothes to sell, and needlework was a huge industry. Only then did the old woman be beaten away.

But there was something that made Song Jiu a headache. The old woman's grandson was a little better, but she didn't know where she learned it. She called Song Jiu "Dad". When the old woman saw that Song Jiu was not evil, she did not stop him. Song Jiu did not let him shout, and the little girl cried. Song Jiu had a headache. She was not married yet. She was a girl following her and calling her father all day!

Seeing Song Jiu come back, he comes again and pounces intimately: "Dad."

Song Jiuying was not right, nor was he not right. The eldest sister sat next to him, neither crying nor laughing. She patted the little girl on the head and walked to the eldest sister: "Sister, you are here, no matter where the restaurant is?"

"Xiaojiu, I'm here to ask you for something."

"Sister, you killed me, how dare I take it as your request."

"You are a big shot, and my sister asks you too."

"Sister, don't say it, I can't stand."

"Xiaojiu, there are diners coming to find that fruit. Teach me how to make it."

Song Jiu nervously pulled his elder sister aside and whispered: "Sister, how much does it cost to make that fruit?"

"I have no idea."

"The cheap one is less than twenty cents, or even ten cents. The expensive one is thirty or forty cents, or the frosting is expensive, otherwise the cost will be even lower. How much will it cost to sell one in the future?"

"What are you selling that for?"

"It's not that I sell it, it's that jade apples will be sold in the future."

“You can’t sell jade apples.”

"Don't worry about Yuping's affairs. If a real man does something, why not have a wife? I tell you that the lowest fruit will be sold for 500 cents in the future, and the higher ones will be sold for a price of 500 cents."

"You want to die and make this black-hearted money!"
Chapter completed!