The ice cubes in the harem of Qing Dynasty are mainly natural ice cubes. Every winter, people in the palace will go to Yuquan Mountain to get ice, cut it into neat blocks and pull it back, then transport it to a special icehouse for storage, cover it with a quilt, and isolate it from air exchange and temperature exchange with the outside world. In case it is hot.

In the Tang and Song Dynasties, people discovered that putting saltpeter into water would make water freeze, and this method could be used to make ice. The chemical name of saltpeter is potassium nitrate. When it is dissolved in water, it will absorb heat and its temperature will decrease, so water will become ice.

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Points for attention in making ice cubes:

1 Don't store the ice cubes or crushed ice in the refrigerator or freezer for a long time. It's best to update them every few days and make them now to prevent pollution. After all, the refrigerator and freezer are not made entirely for making ice, and freezing different ingredients is easy to cause ice pollution.

2. Non-professional families need manpower and tools to make ice, so the hygiene of tools and utensils should be paid attention to when breaking ice.

3. Pay attention to the safe use of instruments.

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