In fact, when he thought of making ice to cool off, Lin Zifan sincerely admired the ancients in China.

As far as Lin Zifan knows, it seems that in the ancient Song Dynasty, someone invented the method of making ice from saltpeter! The scientific name of saltpeter is potassium nitrate, also known as potassium saltpeter, etc., and most of them are colorless, white or gray crystals.

Saltpeter is easily soluble in water, and can also be decomposed at high temperature to release oxygen, in modern times, the main role of saltpeter is mostly used to make pyrotechnic powder, black powder and food preservatives.

But in ancient China, saltpeter was a good thing for making ice!

Because some ancients found that saltpeter would absorb a lot of heat when it was dissolved with water, so that the water temperature would drop or even freeze.

In this way, there was a method of making ice in ancient China, even in the hot summer can also cool off, and later, the traders were also very witty to add sugar to the ice, and even add juice, etc., which is almost equivalent to modern ice cream, and this method, until Marco Polo arrived in China, was transmitted to the world by Marco Polo.

Saltpeter, on the other hand, can be found around earthen houses in addition to saltpeter mines or chemical synthesis. The most likely place to appear is near the thatched pit, pigsty, etc. To put it simply, it is some grayish-white powder or small crystals......

When he was wandering around the palace these days, Lin Zifan had seen this, but he couldn't be sure if it was or not. What he has to do now is to find out and try it to see if it is saltpeter.

Soon after, Lin Zifan found traces of saltpeter around the toilet in the courtyard of a palace maid's accommodation......

When Lin Zifan pouted his ass to collect saltpeter, he was discovered by the palace maids, and then, a group of palace maids pointed at Lin Zifan......

“...... , Is this treating me as a hooligan?MMP yes, wandering around the women's toilet, what a feeling of shame......" Lin Zifan was embarrassed, so he could only collect some saltpeter in three or two clicks, and then ran away.

Saltpeter has a bitter taste, and combined with its shape, if you want to confirm whether these white powders are saltpeter or not, you just need to taste it.

But first of all, the thing itself is not clean, and secondly, Huannima was found by the latrine, so Lin Zifan naturally has no interest in tasting it.

Therefore, to confirm whether this is saltpeter, you can only use other methods.

"Xiaoyan, get me two basins of water, one big and one small!"

Lin Zifan entered the logistics mansion in a hurry, holding the saltpeter and commanded.

"Yes, my lord!" Although Zhou Xiaoyan, who was on a 'turn off' today, was puzzled, she still carried out Lin Zifan's order as always, and soon brought two basins of water.

The small one is an ordinary basin, and the big one is the kind that is used to wash clothes on weekdays, and it is also large, and it must be filled with at least 100 catties of water.

But she is petite, but she walks steadily with a hundred or dozens of catties of water, and can even be described as walking like flying, which makes the corners of Lin Zifan's eyes twitch......

As the weather gets hotter, people wear cooler clothes. Zhou Xiaoyan was washing something before, but at this moment, the two white calves were exposed, and a few strands of hair were attached to her slightly sweaty neck, coupled with her ruddy face, which looked particularly attractive.

But Lin Zifan didn't have the heart to pay attention to these. He poured out some of the water from the small basin, leaving only about half a small basin, then put the small basin into the large basin, and finally put the saltpeter into the small basin.

Since saltpeter will absorb nearby heat when dissolved in water, if Lin Zifan finds saltpeter, then the small basin will continue to absorb the surrounding heat, and the water temperature in the large basin will naturally decrease, even until it freezes.

And in doing so, you can not only confirm whether this is saltpeter, but also solve the trouble of saltpeter is not clean.

Saltpeter is dirty, let's 'isolate' saltpeter, right?

Generally speaking, it is faster to add saltpeter to a large pot to keep the ice cubes in the small pot clean, but now it is only an experiment, and Lin Zifan is lazy to manage so much.

Soon, many ice flowers appeared on the surface of the water in the small pot, and then ice ballast formed and multiplied......

This magical scene made Zhou Xiaoyan's eyes widen: "My lord, ...... are you?"

"It's just a little trick. Lin Zifan also smiled, obviously, this is saltpeter.

After a while, Lin Zifan put his hand deep into the big basin and frowned slightly. The water temperature did decrease, but not significantly.

"It shouldn't be like this......"

He swept his gaze, and finally locked on the thick wooden basin: "Yes, the wooden basin, and it is so thick, the heat transfer is too slow, and now it is confirmed that saltpeter can indeed be obtained, then it will be easy to do." ”

"Zhou Xiaoyan. ”

"Yes, sir. Zhou Xiaoyan responded timidly.

"Take the small basin to the sun to dry, collect the powder left after drying, I have something to go out, and I don't have to wait for lunch. ”

After finishing the order, Lin Zifan left in a hurry, leaving Zhou Xiaoyan slightly stunned.

As a person from the 'tropics', Zhou Xiaoyan had only heard of it, but had never seen ice, but this appearance, and the cold touch, were exactly the same as those recorded in the book. Isn't it ice?

Curious, she reached out and probed into the small basin......

"It's so cool!"

Zhou Xiaoyan looked surprised, the cold ice cubes made her feel refreshed, as if even the coming hot summer was not so uncomfortable.

Then she didn't forget Lin Zifan's entrustment, although she was reluctant, she still moved the small basin to the sun.

And Lin Zifan's side, after sneaking out of the logistics mansion, he wanted to find someone to help, and he wanted to go to the national teacher or General Huo, but after thinking about it, these two bigwigs have too high official positions, and they have been pinching each other, and if they find any of them, they may offend the other person, so they can only give up.

As for finding Ziyi, it's no problem, after all, the empress had instructed Ziyi to cooperate with Lin Zifan. But Lin Zifan believes that this matter must be completed by 'his own strength', and leave a good impression in the empress's heart.

Yes, in the end, Lin Zifan walked out of the palace in a circle, and found a guard to let her lead the way to the mansion of Hubu Shangshu......

Hubu Shangshu Mansion is within the 'first ring' of Chang'an, and those who can settle in this area are at least four-grade officials, and big officials grasp a lot of them.

Under the guards' peeking glances from time to time, Lin Zifan arrived at Shangshu Mansion.

"It's not bad here, although the environment is not as good as the palace, but it is also quite depressing, I didn't expect that Li Shangshu, who has no face and no skin, is quite appreciative?"

"Who are you talking about faceless and skinless?" Li Shangshu didn't know when he appeared beside Lin Zifan, and suddenly appeared like A Piao, startling Lin Zifan......

"Damn!