In the freezing days, the ancients cut the ice into pieces on the river with ice trowels, and each piece can bear the weight of people. But at this time, the ice is not taken out, but it is allowed to continue to freeze, because the cut ice will float up and freeze again after being cold, so there are more thickened ones, and some can even be as thick as one meter. After the thickness is almost the same, people will transport the ice cubes to the cellar dug in advance.

2, saltpeter artificial ice making method

It is said that in the Tang and Song Dynasties, people even found that putting saltpeter into water would make water freeze, so that the ancients could even make ice. It is said that some water is poured into a big basin, then into a small basin, and a basin of water is also poured into the small basin, and then saltpeter is poured into the big basin, and the water in the small basin will become ice.

Extended data:

The history of storing and using ice in ancient China is at least 3000 years. It is generally believed that this tradition has existed since at least the Western Zhou Dynasty. Moreover, harvesting, storing and using ice have all become a complete system.

However, in the south of China, because the temperature is high in winter, it is difficult for water to form thick ice, and it is not easy to transport it, so it is difficult to have ice in summer in the south.

However, since people discovered the saltpetre ice-making method, they can also eat iced food in summer in the south, and after saltpetre is dissolved in water, it can be refined and reused by cooling crystallization or evaporation crystallization, so some people even use it to open a freezing or ice-making factory.

How did the ancients use ice in summer? In fact, it is similar to what we are now. The ancients used it to cool food and drinks in a double-decker box, which is equivalent to the role of a refrigerator.

References:

People's Network-Without air conditioning, how did the ancients escape the summer?