Seeing Li Chunfeng go away under the scorching sun like a fire, Li Xiu couldn't help but sigh with emotion, people always have to pursue a little, for example, like Li Chunfeng, he is a very pursuing person, when he got his consent, he immediately got up and said goodbye, no matter how hot the weather was outside, he couldn't stop his footsteps. Pen @ fun @ pavilion wWw. ｂｉｑUｇE。 ｉｎｆｏ

However, Li Xiu is obviously a person who has no pursuit, stood at the door for a while, and immediately got into the living room with ice cubes, felt the coolness brought by the melting of the ice, and then breathed a long sigh of relief, and secretly prayed in his heart that Li Chunfeng would not faint on the road, otherwise with his appearance, maybe he would be picked up by a female thief to be a man in the village.

"What are we going to talk about today, sir?" Li Xiu just took a breath, and Li Chengdao next to him came up with a smile.

He didn't send Li Chunfeng just now, but stayed in the living room to ask Qi Niang for what he didn't understand in the notes in the past few days, and Li Xiu finally knew the reason why Qi Niang helped him take notes, it turned out to be because Li Chengdao promised her to bring her delicious snacks in the palace every time, but this stupid girl actually sold the fruits of her labor for a few snacks, but to be honest, the dim sum in the palace is really delicious.

"It's so hot today, let's not learn mathematics, I'll give you a debut topic for you and Qi Niang to think about!" Not only does the day be hot, but people are also prone to laziness, not to mention that Li Xiu is not a qualified teacher in the first place, so he came up with such a lazy way.

"Okay, okay, I've been bored with learning for a long time, brother, what is the problem?" Qi Niang immediately agreed, she was in a fun and active period at a young age, and she was bored with studying every day, which was also a normal reaction of children, thinking that when Li Xiu went to school, he even thought about setting the school on fire that day, or flooding the school, so that he didn't have to go to school.

"Very well, so why do we feel so cool when we put ice cubes in the room?" Li Xiu said with a smile.

"What's there to think about, the ice cubes are so cold, they will naturally feel cool when they are placed in the room?" As soon as Li Xiu's words fell, Li Chengdao said inexplicably, and Qi Niang next to him also felt a little puzzled, because in their opinion, this was originally a matter of course, and there was nothing to think about at all.

"I knew you would say that, but if you think about it, what kind of changes have happened to the ice cubes in the room to make the surroundings cooler?" Li Xiu said with a smile, ice cubes melt and absorb heat This is a very simple physical principle, but for people who have never been exposed to the discipline of physics, it is not so easy to figure it out.

Hearing Li Xiu's words, Li Chengdao couldn't help but show a contemplative expression, Qi Niang was even more clever to run to the side of the ice basin, carefully observed the changes in the ice cubes, and even stretched out her little hand to touch the ice cubes, but after a while, she hurriedly withdrew her hand and put it to her mouth to breathe.

"It's cool in the room, but the ice is melting, is that why?" After all, Li Chengdao was older, and he quickly thought of the key, but he still couldn't say the specific reason.

"Hehe, admit that your sentence is finally to the point, the ice melts, and the temperature in the room also decreases, which has an inevitable connection, when the ice melts, it needs to absorb the surrounding heat, causing the temperature to drop, in the same way, when the water turns into ice, it will release heat, which is a very simple physical principle......"

Li Xiu derived more physical principles from the physical principle of melting ice and releasing heat, and extended more physical principles, these phenomena are very common in ordinary life, but Li Chengdao has never paid attention to it, and now after Li Xiu's explanation, he immediately has a feeling of being sudden, as if life is full of knowledge, which is not something that the teacher in the palace can teach him.

"Brother, you said that water will release heat when it freezes, so will it freeze if we let the water release heat?" At this time, Qi Niang suddenly interrupted Li Xiudao, a pair of big eyes were also full of little stars, in such a hot weather, if you can make ice cubes, then you don't have to worry about no ice food to eat in the future.

"Qi Niang, don't dream, if you want the water to freeze, you have to wait until the weather is very cold, or find a very cold place, otherwise it is impossible to let the water release heat!" Without waiting for Li Xiu to speak, Li Chengdao spoke out to deny Qi Niang's idea, he felt that Qi Niang was simply whimsical.

"Hehe, admit that you are wrong, what Qi Niang said is very reasonable, and I just happened to know that there is something in this world that can really let water heat up and turn into ice." Li Xiu said with a smile, although the weather was hot before, it was not yet time to cool down with ice, so he was not prepared, but he didn't expect that today's temperature would soar so much at once, it was so hot that it was desperate.

"Is there really anything that freezes water?" Li Chengdao heard this but said in disbelief, if there is such a thing, then ice cubes will not become a luxury in summer, you must know that ordinary little nobles can't afford to use ice cubes!

Before Li Xiu could speak, he saw the door of the living room open, and then he saw the sweaty Princess Pingyang walk in, and when she felt the cool air in the living room, she couldn't help but smile: "It turns out that Dao'er has already sent ice cubes, and I am worried that the weather is too hot today for you to stand it, so I also asked someone to pull a cart of ice over, since I can't use it, I will let people pull it back and store it in the ice cellar!" ”

"You don't have to pull it back, it's such a hot day and it comes back and forth, and it's only half left to pull it back, and the ice sent by Chengdao is more, it's not enough at night, and there are also my family's subordinates, wait for the next person to give them a big piece of ice back, so as not to sleep at night!" Hearing this, Li Xiu hurriedly stopped.

"Huh? You...... You let the next person cool down with ice cubes? Princess Pingyang obviously asked in disbelief, not that she looked down on people, but that the ice cubes in summer were too precious, even if they were used very sparingly in the palace, only when the heat was particularly strong, they would use ice cubes to cool down, and sometimes even give ice cubes to the minister as valuable items, so even if they were extravagant nobles, summer ice cubes were very expensive luxuries in their eyes.

"It's just a cube of ice, if the princess wants it, wait and see me conjure a spell, and then you can do as much as you want!" Li Xiu suddenly smiled mysteriously and said, he was going to say it directly just now, but since Princess Pingyang is here, let's show her a little magic.

"What little spell?" Princess Pingyang still didn't react at this time, and asked with a puzzled expression.

"Sir said he could make the water freeze!" At this time, Li Chengdao opened his mouth to explain, even if he was convinced of Li Xiu's knowledge, he was still a little skeptical about this matter, because it was too beyond his imagination.

"How is this possible?" Princess Pingyang's reaction was almost exactly the same as Li Chengdao's, and her eyes were wide open looking at Li Xiu, in Li Xiu's eyes, her current appearance was much cuter than Li Chengdao just now.

"Of course it's possible, but it just needs one thing!" Li Xiu said and beckoned to the maid helmet behind Princess Pingyang, the helmet didn't understand what he wanted to do, but he still walked over, and then Li Xiu whispered a few words in her ear, and then the helmet nodded and ran out.

"Li Xijiu, what are you letting the helmet do?" Princess Pingyang asked curiously again.

"Hehe, go get something, and you'll know when you wait until the princess." Li Xiu smiled mysteriously again, he deliberately sold a pass, after all, there was no surprise if this thing was put bluntly.

After a while, he saw the helmet running back sweating profusely, Li Xiu deliberately went out to greet him at this time, and took something from the helmet's hand, but he didn't let Princess Pingyang see them, and then he found a copper basin and poured some water into it, and poured the contents of the bag into it, and then walked into the living room with a basin and said: "The time to witness the miracle has come, everyone, please look at this basin of water!" ”

Li Xiu said and put the copper basin on the table in the living room, Princess Pingyang, Li Chengdao and others all surrounded him, and even Yuechan and these maids looked at this side curiously, only to see that the water in the copper basin first came out with a trace of coldness, and then a little ice flower appeared on the water surface, and then the ice flowers were connected, and the ice on the water surface finally appeared.

"Yikes! It's really frozen! Qi Niang saw the strange changes in the water, and clapped her hands and shouted excitedly, after all, children are simple, and they don't think as much as adults, she just feels that her brother's spell is too magical.

"It's really freezing!" Princess Pingyang whispered to herself in disbelief, and her eyes looking at Li Xiu were also full of doubts, she believed that Li Xiu didn't know any spells, but it was too incredible to let the water freeze.

"Sir, what is that kind of thing that can heat the water, you must have added something to the water, right?" At this time, Li Chengdao suddenly figured it out, and shouted excitedly at the moment.

"Hehe, admit that you're right, the mystery of freezing water is worthless, everything depends on this thing!" Li Xiu said and took out something from his sleeve, which was exactly what he asked the helmet to retrieve just now, and he deliberately kept a little.

"What is this?" Li Chengdao looked at the white powder in the paper bag in Li Xiu's hand and asked curiously.

"Isn't this saltpeter, when my eyes were uncomfortable before, the doctor prescribed me this medicine." Princess Pingyang recognized the thing in Li Xiu's hand at a glance.

"Yes, this is saltpeter, just now I asked the helmet to go to the princess's house to get it, this thing can absorb heat when put into the water, so that the water freezes, it can also be used as medicine, it will also be used when dyeing clothes, in addition to it has one of the most important effects......"

Li Xiu was suddenly stunned when he said the end, and did not say any more, because he didn't know what kind of impact would be if the most important role of saltpeter was told? (To be continued.) )