There was no air conditioning fan in ancient times, and there was no ice in summer, which was not too painful. When we watch costume dramas, we can see the concubines in the harem. In summer, they put ice cubes in the room. Then how did they get the ice? Many people say it was produced by the crew. In fact, the ancients also had ice in summer. We can't live without the refrigerator all summer. The refrigerator is absolutely standard at home. Bingo, ice cubes and ice cream are definitely bars. But how did people spend the summer when there was no refrigerator in ancient times?

The ancient people had two sources of ice in summer, one was rivers or lakes in winter, and the other was artificial. The first method is to cut the ice on the river into pieces with an ice knife when the river freezes, that is, on the third or ninth day. Each piece can bear a person's weight, but it can't take away the ice. It can only keep him frozen. Because the cut ice will float, and continue to freeze after cooling, which will make the ice thicker. Sometimes it can reach more than one meter thick.

When the thickness is similar, people will put the ice in the prepared ice room and store it for summer use. There is no ice in the freezer. They are all together. There must not be much space.

Then cover the freezer tightly to store the ice cubes in May and June next year. At this time, you can take it out for use or sale. Some people think that ice can't be released in May and June next year. Can the ice not melt? Actually, it will melt a little, but the ice will not melt. In half a year, the amount of ice melting is very limited. The ice in the freezer was well preserved when it was taken out. At this time you can cut it into small pieces and sell it.

The ancients not only stored ice, but also made ice. It is said that in the Tang and Song Dynasties, people even found that putting saltpeter into water would make the water freeze, so that the ancients could make ice. The chemical name of saltpeter is potassium nitrate. When it is dissolved in water, it will absorb heat and lower the temperature, so the water in the small basin will form ice.