Xia Ning didn't disturb everyone's work, silently looked at the door and left.

Next, she went to the greenhouse and mulberry orchard, and almost knew it, and then she entered her operation room and began a new round of development.

She's going to make ice!

She had previously checked the information on the way saltpeter was made into ice, so she planned to try to make it, and if she could, it would reduce the heat of summer for everyone.

Especially in the major work sites of the base, they have to work every day, so it is even more necessary to cool down.

Moreover, the cost of saltpeter ice making is not very high, it is very suitable for large-scale production and use, and the most important thing is that this method is very simple, after she tries to make it first, she can directly hand it over to the base for development and distribution.

Last time in the electrical mall, Xia Ning had bought an ice machine, and she also thought that it would be much cooler to have an ice machine in the hot summer, and when the base has a power supply, she may be able to use it.

Before that, when you needed ice, you could switch time and space and go to a modern villa to make ice.

So, she has a machine, but now the base has no conditions for use, but there is a manual shaved ice machine that does not use electricity, but this thing must first have ice cubes to make shaved ice to eat.

Therefore, Xia Ning did not consider the machinery and equipment in the porcelain basin space at all, but used the most primitive and simple saltpeter ice making method.

Taking a step back, even if there were ice machines, she wouldn't be able to provide a piece of equipment to every household in the base, right?

Saltpeter ice making is different, this production method is simple and easy to operate, it can be done by anyone, it can be popularized in a large area, and it can also be produced in large quantities, which is much more practical than ice machines.

Just before she was buying objects for heat refuge, she bought some saltpeter by the way, and thought that this thing might come in handy, but then she was busy, and there were too many materials in the porcelain basin space, so she forgot about it for a while.

This amount is at least enough for their base to collectively use it twice, and after two days, they will go back to modern times to purchase, in fact, there are ways to obtain saltpeter in ancient times.

Generally, there are nitrate-containing clods on the side of the walls of earthen houses in ancient times, sweep them and put them in barrels, soak them in water, filter them, boil or dry the filtrate to obtain saltpeter crystals.

In addition, it can occasionally be found on certain rock faces, caves, or salt marsh areas.

Therefore, in the crisp autumn season, it usually precipitates out in the form of a crust or salt flower, covering the ground and the foot of the wall, which is the so-called frost, especially in the corners of the walls near the pigsty, stables, and toilets.

However, the base is not suitable for searching for saltpeter now, but this method can be told to everyone at that time, so that the base will save a lot of trouble, as for whether the base is willing to tell the villagers, or how to apply this method, then she doesn't care.

Then, Xia Ning took the operation room to start the ice-making work.

First, the water is placed in a small container, then placed in a large container with water, and saltpeter is added to the large container continuously, during which the water in the small container is slowly frozen.

Because saltpeter, when dissolved in water, absorbs heat and lowers the ambient temperature, if the water in a large container solidifies, saltpeter will reappear, and most importantly it can be reused.

This is also the reason why the cost of saltpeter ice making is low, and it can also be produced in a large area.

Xia Ning spent half a day getting more than a dozen pots of saltpeter, just waiting for the afternoon to see if it could freeze.

"Xiao Ning, I heard you're making ice?"

"Can you still make this ice cube yourself?"

"yes, that's incredible, how do you make ice in the summer?"

"Second sister-in-law, can you let me take a look? It feels amazing, the ice cubes we used in the summer in previous years were specially stored in the winter. ”

"Little sister-in-law, can we use ice to make ice fruits to eat?"

At noon, everyone in the Song family returned home and heard about Xia Ning's ice-making, and everyone was shocked and curious.

"Since everyone is interested, let's take a look with me."

Xia Ning didn't want to explain the principle in a puzzling way, so she simply took them directly into the operation room to see the production process with her own eyes, and demonstrated it to everyone while explaining, presumably they would be able to understand it more intuitively.

So, everyone in the Song family followed Xia Ning into the operation room and watched her personally operate how to make ice from saltpeter, and everyone who watched this process was directly stunned.

"Gone?"

"That's it? Is there something missing. ”

"Wouldn't that be too easy?"

"Well, it's not quite what we imagined."

"Lemon, can you make ice cubes this way?"

Everyone in the Song family looked incredulous, in their phenomenon, it must be a very complicated and difficult thing to do to be able to make ice cubes in the summer, but they never expected that it would be just a few steps.

How can it be so simple?

It's so simple that they all doubt their lives.

If they knew how to make ice in the past, then why did they need to spend money to buy ice cubes in the summer? Or you have to build a cellar in advance, which is time-consuming and laborious to store in advance.

They may even be able to rely on this method to make a lot of money from those powerful families in the capital.

But it's not too late to know, at least for the rest of the summer, they don't have to worry about running out of ice.

Listening to everyone's speeches, Xia Ning couldn't help but smile and said, "This is just the production step, it hasn't frozen yet, it will take about half an hour, in fact, the way of making ice is not very difficult, but no one has ever tried it before, so everyone will feel a little incredible." ”

"Little sister-in-law, can I eat this ice?" Sister Ying looked at the ice basin and couldn't help pursing her lips, looking like she couldn't wait to eat ice fruit, she really hadn't eaten ice fruit for a long time.

Xia Ning responded, "The ice in these two basins is edible, but the ice in the other basins is inedible." ”

"Why?"

Sister Ying asked puzzled.

"Yes, isn't it different from this made of ice?"

Not to mention that Sister Ying is puzzled, even the adults are also a little confused.

"Of course, there is a difference, this saltpeter actually contains a certain amount of toxin, and in the process of making it, we have to think about whether the ice made is for consumption? Or is it going to be used to cool down the heat? There's one slight difference between the two."

Next, Xia Ning patiently explained to everyone the precautions for saltpeter ice, especially the food and the work should be clearly distinguished, like ice cubes purely used for cooling, in fact, the method of making is simpler, without basin isolation, you can directly mix it in water.