Listening to Li Shimin's business, Li Mu also cheered up and led Li Shimin to the anvil to show the heating coal stove he had built in the past few days. This heating coal stove is not from the system, after all, the system he brought is a game system, and the characters in the game don't need to be heated, so naturally there is no heating coal stove. This heating coal stove was built by Li Mu according to the memory of his previous life, when he was a child, there was no heating in the orphanage, and the heating coal stove was used for heating in winter.

When it snows, the children gather in one house because the orphanage has limited funds and can't buy much coal. At this time, the old dean will also stay with the children, because he is worried that if he does not watch, the children will have problems filling the coal themselves. The degree of coal consumption is quantified every day, and it is good to weigh it with a table scale, and how many catties per day can not be exceeded. If it does, the orphanage will be left without coal before the snow melts the following spring.

And more importantly, he was worried that the child would fill in the coal by himself and get gas poisoning.

But in fact, the probability of danger in heating coal stoves is already very low. Basically, an adult, with a little attention, there will be no problems. In the eighties and nineties, when buildings were not yet widespread, coal stoves for heating were a must-have for families in the north.

This thing is very simple to make, you don't need too good steel, the most inferior cast iron will do. With the iron-smelting process of the Tang Dynasty, it is not difficult to make at all. As early as the Qin and Han dynasties, when making bronzes, the people of the Central Plains had already mastered the process of making bronze molds, making heating coal stoves, and using this process was just right, but it was just replacing bronze with iron, which was very simple.

Li Mu found a few craftsmen who made bronzes in the Ministry of Industry, drew drawings for them, and let them fire molds. The furnace he is showing Li Shimin now is made of this mold.

The stove on the stove was made by himself. Connected together, and then sealed with mud, a standard 80's heating coal stove is complete.

Li Mu was very satisfied with his craftsmanship, and he was very confident that this cast iron coal stove was much better than the stove he used to heat rice when he was in elementary school. But obviously, Li Shimin doesn't know how to appreciate it. He watched from the side for a long time, but he really didn't understand the point, pointed to the coal stove and asked, "What is this for?" ”

"Does Your Majesty know about Coal Stone?"

Li Shimin nodded and said, "Naturally, I know that although coal and stone can be burned, they must be ventilated, otherwise poisonous smoke will be emitted." Therefore, it cannot be used for heating, but only for striking iron...... What are you mentioning this for? ”

"Your Majesty, with this thing, you can solve the problem of poisonous smoke." Li Mu Zhengse said: "Winter is approaching, and it will almost snow in another month, I asked Yu Langzhong, and he told me that this coal and stone are just around the corner." If this is the case, wouldn't it mean that my Datang has an inexhaustible supply of fuel? If the people had this furnace, would they still freeze to death in winter? ”

Li Shimin listened to Li Mu's words, and the first thought that came to his mind was 'Arabian Nights'. From ancient times to the present, who does not know that coal and stone are poisonous, if it is not really poor, can not afford charcoal, can not get dry firewood, who will risk death to use this thing for heating? Everyone knows that coal and stone are combustible, but since the Qin and Han dynasties, few people have used it, doesn't this explain the problem?

And Li Mu has now come up with a strange-shaped 'stove', and he said that this problem has been solved, how can Li Shimin believe it?

Li Mu saw it, and without waiting for Li Shimin to speak, he took the initiative to say: "If Your Majesty doesn't believe it, the minister will demonstrate it for you now." ”

Speaking, without waiting for Li Shimin to agree, Li Mu called Li Chongyi to bring coal over, Li Chongyi heard Li Mu's order, went to the library to carry a large basket of coal, which weighed hundreds of catties, but in his hands, it was as easy as carrying a chicken.

The basket was put down heavily, and Li Mu threw the coals into it one by one. Then the fire was started from under the furnace with dry branches, and the coal kept by the Ministry of Industry for ironmaking was good coal, and when it caught fire, the fire soon exploded. Although Li Shimin did not escape, he also raised his hand to cover his mouth and nose with his sleeve, and said: "Li Mu, you look at the smoke, this is coal poison, do you want to poison me?" ”

"Your Majesty, wait a minute!" Li Mu scolded in his heart, why was he so unlucky, he caught up with the stormy weather, he hurriedly brought the bamboo fan over and let Li Chongyi fan the wind.

Anyone who has ever had a stove knows that even if it is a windy day, as long as the stable combustion turns red and the heat rises, it can bring the wind smoothly, and the smoke is only for a while. But there was a bit more coal filled today, and after about a stick of incense, the coal turned red and the smoke stopped.

Li Shimin has endured it and not left, he is not afraid of life and death, but Li Mu has not left, he wants to see what kind of reputation Li Mu wants to make. He saw the change of the stove with his own eyes, and felt the most real, he didn't expect Li Mu's stove to really become, although it was choking at the beginning, but he also knew that it was related to the direction of the wind, even if it wasn't this stove, when the army was burying the pot and cooking, there was also a wind, which was not a problem.

When the smoke dissipated, Li Shimin put down the hand covering his mouth and nose, got close and smelled, and didn't smell the choking smell anymore, he followed Li Mu's example, took the stove hook in his hand and lifted the lid, and saw that the smoke produced in the stove went out along the iron cylinder above the stove, and couldn't help but be very surprised, and said: "Aiqing, can you control smoking?" ”

Li Mu slandered in his heart, boss, you are really realistic enough, you usually call your name, and you are angry and call you a boy, now that you see something, Aiqing is here, and the difference in treatment is really obvious.

Li Mu hurriedly squeezed out a grateful expression and said, "Your Majesty, it's not that the minister can control smoking, but that the minister discovered the reason why the smoke rises, so he made a stove and took the smoke out." Now that Your Majesty has seen it with your own eyes, do you think that the minister's invention can be used? ”

Li Shimin pondered for a moment, shook his head, and said, "This stove is usable, but it is not practical for the people. Li Mu, have you ever thought about how much this furnace costs? My Datang is already short of iron, and your stove will cost hundreds of catties of iron, hundreds of catties of iron, which is not a problem for the princes and nobles, but for the people, they can't afford it at all. ”

Li Mu had already thought of it and said, "Your Majesty Shengming, you can see through the disadvantages of this heating coal stove at a glance. That's right, the cost is the biggest obstacle to the implementation of the heating coal stove, the minister thought about it for a long time, and finally let the minister think of the second way. ”

After Li Mu finished speaking, he took Li Shimin to the next door, that is, the room where he was usually tired from being busy in the studio and taking a nap. In this room, a wall of fire has been built, which he asked Yu Wengui to send someone to repair a few days ago.

"Your Majesty, please see, this is another way that the minister has come up with. Your Majesty has just seen that the reason why the heating coal stove can avoid poisoning is the result of the export of flue gas, and the most important thing in the use of coal and stone is this export of flue gas. Li Mu walked to the wall, stretched out his hand to touch the wall, and said, "This wall is a double-layer wall, hollow. The minister burns coal here, and the smoke can pass through the hollow wall and then exit. The minister asked the craftsmen to burn the same cylinder tiles as the iron cylinder that His Majesty had just seen, and by connecting these tiles together and sealing them with mud, they could also have the same effect, and they could be heated without the use of iron. ”

Li Shimin took a closer look, just now he saw Li Mu's demonstration, and then looked at this wall of fire, it was almost understandable, but when it came to people's livelihood, it was not allowed to be sloppy, Li Shimin still asked Li Mu to demonstrate in front of him.

Li Mu had no choice but to ask Li Chongyi to take the coal, put it in a brick-built stove, and then light it, and sure enough, as Li Mu said, the smoke was exported, and the whole wall was hot.

Li Shimin finally showed a satisfied expression, and laughed: "Aiqing is talented, this wall of fire is not difficult to build, and the people themselves can build it, and the coal and stone are just around the corner, it seems that the people of my Datang will not have to be frozen in the future, hahaha......"

"And." Li Mu interrupted Li Shimin's laughter, making him almost choke on his own saliva. Li Shimin glared at him unhappily and said, "What else?" ”

"Your Majesty, please be seated." Li Mu gestured, and Li Shimin noticed that there was a knee-high step behind them, and he sat on it like Li Mu, feeling that it was hot under his buttocks, and couldn't help asking, "What is this?" ”

"Your Majesty, this is a pankang, and it is also the invention of the minister."

"Pankang?" Li Shimin frowned and said, "I've only heard that there is a kang in the north, but what is a pankang?" What's the difference? ”

Kang is not an invention of the Goguryeo nation, and there was already a prototype of Kang in the Western Han Dynasty in China. It's just that the kang at that time was still very simple, with a stone slab as a cover, digging a hole underneath, heating the slate, and waiting for the slate to cool down, and then lying down to sleep, which was not very practical. After it was gradually abandoned, if the world talked about 'kang', it still belonged to the best technology of the Goguryeo people.

"The New Tang Dynasty Book: The Biography of Goguryeo" contains: "The winter moon is a long kang, and a warm fire is burned below", the kang of Li Mu's hometown of Mayi is also the technique passed on by the Goguryeo craftsmen who were captured when Emperor Yang of Sui conquered Goguryeo. The general structure is similar to that of later generations, but the smoke mouth is flat, that is, it burns here and rises there, and the smoke stays in the kang for a short time and cools quickly.

And Li Mu made this pankang, is the era in which he lived in the later generations, has summed up the experience of his predecessors to build the flower pan kang, he really wants to directly make a hollow pankang in one step, but there is no cement, can not make a high strength and large enough area of the kang board, can only use bricks to build the flower pan kang. There is a flue built in the middle of the flower pan kang, the smoke comes out from the stove, it takes more than ten weeks to be coiled in the flower pan kang to be able to disperse smoothly, because the flue coiled and coiled by the brick, the smoke is also coiled and wound, so it is called the pankang.

At that time, it took at least 800 years for the Kang of Goguryeo to evolve to the level of the Huapan Kang. Li Mu took out the pankang at this time, which was definitely an invention several eras in advance.

Li Shimin saw that the door was coming, Li Mu was connecting the wall of fire to this pankang, the smoke of the fire wall, to walk out of the pankang, in order to really disperse, I also admired his ingenuity, even can kill two birds with one stone, a coal and stone for dual purposes, this wall of fire plus pankang, the temperature in the house suddenly rose.