Song Jiu first took out two small firecrackers, disassembled one firecracker, and lit it, and once it was burned, it was gone, and the other firecracker did not move, so he also lit it, and said: "Why can a firecracker only burn, not explode?" ”

I don't know who first invented the use of gunpowder to make firecrackers, but since it appeared, it has been seen that it must be wrapped in paper before it can be set off. If there are children who are not put away, adults will not think about it seriously.

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

Then he took out an iron rack, a candle, a few pieces of paper, a teacup, a kettle, two small benches, a sandbox, a few pieces of iron ore, a large bellows, and a bow ball from the next room, and put them all away.

First, the 20 officials who were sitting on pins and needles were given pens, ink, paper, and inkstones, and the students were so frightened that they did not dare to give lectures, and they snatched the emperor's throne, and they were also trembling and terrified. Song Jiu said: "Everyone, listen carefully to my lectures, make notes on important places, and ask questions if you don't understand." ”

Then the candle was lit, a piece of paper was placed on the candle, and it burned in the blink of an eye, saying: "Everyone, it is not immediately ignited, 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 be burned, the second must have combustibles, such as air and oxygen, and the third must have an 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 in the mine, which is what the miners call underground toxic gases. One is that they will endanger the lives of miners, and the other is that they will have some effects on lead burning, please record. ”

It's relatively simple chemistry, but everyone is dumbfounded.

But it does need to be understood, at least to understand a rough idea, before it can be successfully blasted in the future, and it will also reduce the survival rate of miners.

This is not the first lesson to be taught, Song Jiu folded a carton with paper again, put it on the iron shelf, poured a little water from the kettle into the carton, moved the candle under the carton, and said: "Look at it again, the paper can't burn, because it transmits the heat to the water, so the paper has not reached the ignition point, when to boil the water dry, when to burn the paper." The heat transfer performance of each object is also different, iron is faster than wood, I wear armor to the soldiers, the armor is made of iron, the effect of cold and heat transfer is good, it is hotter when it is hot, and it is colder when it is cold. Therefore, the winter in the north and the summer in the south became the time and place that our soldiers feared the most. This is not your concern for the time being, I will only talk about this water, do you see it, the water boiled immediately, but where did this water go? It becomes water vapor, water has three forms, solid is ice, liquid is water, gas is water vapor, our sky has a lot of water vapor, accumulated to a certain point, when these small water droplets accumulate to the atmosphere rising air flow can not support, it will rain in summer, if the sky is very cold, in the process of falling condensed into solid, it is snowfall. ”

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

"Zhao Xianggong is wise, I heard it immediately, this sky is not a vacuum, it also has a lot of substances, because it is formed in a gaseous state, we can't see it or touch it, and then look at a test test," Song Jiu poured the teacup full of water, and the water flowed down as soon as he crooked it: "What will flow down because of gravity." ”

Then he poured the teacup with water, covered it with paper, tilted it carefully, poured it horizontally, let go of the hand covering the paper, and covered it with a piece of paper, and the water did not leak a drop, which was very strange, and there was a lot of discussion together.

"The actual reason is very simple, the air is not empty, there are all kinds of substances, it will produce all kinds of pressure, forming pressure on the paper, so a thin piece of paper holds a glass of water, canceling out the gravitational pull of the earth." Song Jiu and twenty other officials took it to memory, did another test, put the bench on the sand, and said: "You see, the more stones you press, the greater the pressure, and the deeper you will sink. This is called pressure, and what is pressure is that the pressure per unit area is different. ”

Another test was done, and the four legs of the bench were lowered to the stone, and the stone was pressed, and the other bench was placed face down and the foot was up, and the same stone was placed.

Use these simple tests to let everyone have a preliminary understanding of pressure, pressure and combustion, Song Jiu did another test test, and took the ball over, the Tang Dynasty was a bow, that is, polo, the Song Dynasty lacked horses, playing step, juju, that is, playing football, but the rules are different, but football is very standard, and some good football elasticity is not much worse than that of later football. It's just that the cost is more expensive.

I pumped it in with the air pipe input from the bellows, and after hitting it to the fullest, it burst and exploded. Song Jiu said: "Why will it be fried?" It is precisely because more air is delivered to it that the pressure is getting higher and higher, and the unit pressure is also increasing, and this pressure exceeds the limit of the leather to bear, and it explodes after the worst. ”

"Let's talk about firecrackers again, what is it for them to be sealed and fried, and if they are not sealed, they are burned? It is this pressure factor that makes it safe and sound when it encounters fire, and when it encounters fire, it can form a high-temperature and high-pressure gas in an instant, which makes the surrounding material that binds it suffer a strong impact, resulting in deformation or fragmentation. If it is not bound, the pressure will be dispersed quickly, and it will not form a very powerful pressure, and it can only be burned but not fried. That day, I did a test and let that box of gunpowder blow up the city wall, in fact, if the conditions allow, it will be more powerful, and even that box of gunpowder can blow up a small mountain. Of course, this is impossible. For example, "Song Jiu pushed the teacup on the table: "From a mechanical point of view, because of the inertia of the force, the teacup can move all the time, but in fact it only moves a little, for what, there is gravity, friction, resistance, and so on, so that the teacup finally stops." The same is true of gunpowder, we can only implement theoretical tightness, and various objective factors will make its explosive power infinitely reduced. As he spoke, he wrote a set of formulas, that is, the explosive yield of that box of gunpowder. But if there is no detailed explanation, this explanation will be very troublesome, and no one will understand the explanation, so it can only be understood by twenty officials.

This is the cause of the explosion of gunpowder, precautions, and so on. While talking, I tried and tested, strange knowledge, strange lectures, but everyone actually listened to it, and listened to it with relish.

After a class, Song Jiu said: "Everyone, please ask questions, one person must ask more than three questions. ”

These officials and craftsmen are also educated, all of them are traditional forms of education, I don't know if they understand the Tao, although they have made records, none of them have asked questions, so Song Jiu forced them to ask questions. Only by asking can you deepen your impression. If a student doesn't know how to ask questions, it's hard for the student to get good grades, and if a teacher doesn't like students to ask questions, it's also hard for the teacher to be a good teacher.

began to answer shyly, but Song Jiu forced them to ask, so they had to ask, and the more they asked, the more enthusiastic they became, and even Zhao Kuangyin asked a few questions.

It was dark and Dusk, and Song Jiu stopped.

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

There are many ministers who are bowing their heads and talking, and after speaking, they are no longer so mysterious, and they feel a lot of understanding and excited.

This effect is what Song Jiu wants to see the most, it is useless to promote it by himself, and it has to be promoted from top to bottom by the imperial court. Just like cotton planting, it has been very slow, Zhu Yuanzhang issued an edict to plant cotton all over the country, and all of a sudden there was cotton in the whole country.

I wonder if Lu Dao found cotton seeds from the Western Regions and Lingnan at this time, can he plant them alive?

I think too much, if I live, there is still work to do, the weaving machine! Do you want to live anymore? Let's get steel first.

Sending Zhao Kuangyin and his entourage away, Song Jiu reprimanded twenty-one students again.

Junchen now has some misunderstandings about Song Jiu, this is something that can't be helped, 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 probability of children from poor families being corrupt a little higher, they were too poor before, and their ability to resist the temptation of wealth is relatively weak. Some gentlemen teach wealth to their students like a flood beast, and the same is true of the country, touting hermits, hermits are noble in spirit, and wealth and power are like floating clouds, but how many people can do it?

So Song Jiu went the other way, it's better to fill it up than to be sparse, don't be afraid of it, wealth is not so evil, but it must be within the rules to seek wealth. As the Master said, as long as you give me money, even if you let me take a bullwhip, the income from my labor is not ugly.

Of course, these views must have been in serious conflict with the two doctors, from a small quarrel for three days to a big quarrel for five days.

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

The old lady of the Zhang family sat under the locust tree with her two children, waiting for him to come back, and the eldest sister came to cook the meal herself.

The old woman came to Song's house nervously, in fact, Song Jiu was very depressed, the old woman wanted to sweep the floor, where to let her sweep, Song Jiu taught practical classes, and also cultivated students' hands-on ability, and did not want to raise their bodies to be pampered, students took turns to clean, in front of the hospital and behind the house, tidying up some equipment, pen, ink, paper, inkstone, sundries in the school, and even eating tea let them go to the kitchen to burn in person. Chai He bought it back, and one, two, three moved to the kitchen room. The rest of the things are either washing clothes, Song Jiu doesn't want her to wash the clothes, or cooking, the old man's situation is not very good, although his son died in battle, he died as a small soldier, the Northern Han Dynasty is so poor, where will there be a pension? What delicious can she make?

But the old man is a working person, how uncomfortable is it to not let her do things? Song Jiu was helpless and said, old lady, you learn needlework, earn a little money, and think about your grandchildren's future. At this time, there were not many ready-to-wear garments sold, and needlework was a huge industry. Then the old woman was sent away.

But there is one thing that makes Song Jiu have a headache, the old woman's grandson is a little better, that is, he speaks less, the granddaughter doesn't know where he learned the Tao of Lu, as soon as she sees Song Jiu, she shouts "Daddy", the old woman sees that Song Jiu is not evil, and she doesn't stop it, Song Jiu doesn't let her shout, and the little girl cries. Song Jiu has a headache, he is not married yet, and a girl follows him all day long and shouts Daddy!

Seeing Song Jiu coming back, he came again, and pounced affectionately: "Daddy." ”

Song Jiu should not be, should not be, and should not be. The eldest sister sat on the side, neither crying nor laughing. patted the little girl's head and walked up to the eldest sister: "Eldest sister, you are here, no matter where the wine shop is?" ”

"Xiao Jiu, I came here to ask you for something."

"Eldest sister, you killed me, how dare I beg you."

"You're a big shot, and my eldest sister asks for it."

"Eldest sister, don't say it, I can't stand it."

"Xiao Jiu, a diner came to find that fruit, you teach me how to do it."

Song Jiu nervously pulled the eldest sister aside and whispered, "Eldest sister, how much does it cost to make that fruit?" ”

"I don't know what to do."

"The cheap one is about twenty yuan, or even only ten yuan, and the expensive one can have thirty or forty yuan, or the icing is expensive, otherwise the cost is lower, how much can you guess it can be sold for in the future?"

"What are you selling that for!"

"It's not me who sells it, it's that Jade Apple will sell it in the future."

"Jade can't be sold either."

"Don't worry about Yuping's affairs, if the eldest husband has something to do, why should he have no wife? I say to you, "The lowest one will cost five hundred cents, and the higher one will cost it for one penny." ”

"You're going to die, make this black money!"

"Can the poor afford to sell it for fifty cents? Still can't afford it. It can't be sold anywhere you want, and once you sell it in a small wine store, its value will plummet. You and your brother-in-law don't worry, you will be busy in the future. Don't talk about it, I'll eat first, and I still have work to do after eating. Song Jiu hurriedly called the four painters to come to dinner, and after eating, he had to do a serious thing, sticking a painting!

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