Traditional customs of the old days. Also known as "storing ice".

As early as the pre-Qin period, people used natural ice to refrigerate, preserve food and make cold drinks. According to Zhou Li, at that time, in order to ensure the use of ice cubes in summer, the Zhou royal family set up a corresponding organization to manage the "ice policy", which was called "Lingren" by the person in charge. The establishment of this department is not small, with 80 "employees". Generally, from June 5438+February every winter, workers began to store natural ice cubes.

Every year during the severe cold season, the ancients began to chisel and store ice. Officials in charge of ice storage supervised slaves and farmers to dig in places with good water quality and hide them in ice rooms prepared in advance.

The igloo is built deep in the cool underground. Spread the ground with fresh straw and reed mats, put ice cubes on it, cover it with heat insulation materials such as rice chaff and leaves, and then seal the pit for next year.

Because of this storage method, about two-thirds of the stored ice will melt every year, so the ancients often increased the amount of stored ice to three times the amount needed.

Step 2 make ice

Around the end of the Tang Dynasty, craftsmen mined a lot of saltpeter when producing gunpowder. Occasionally, they find that saltpeter absorbs a lot of heat when it is dissolved in water, which can cool the surrounding water until it freezes. So some skilled craftsmen began to make ice with saltpeter.

The craftsmen put the water into the jar, took a bigger container, put the water into the container, then put the jar into the container, and constantly added saltpeter to the container, so that the water in the jar turned into ice.

Nitrite is a white bitter crystal, and its color is like frost. The chemical name of saltpeter is calcium nitrate. When it is dissolved in water, it will absorb a lot of heat, thus lowering the surrounding temperature and forming ice.

Extended data:

Source of pit ice:

It's hot in summer and freezing in winter in northern China, so it's a custom to store ice cubes in the freezer in winter for the next summer. The origin of this custom is very early, recorded in the Book of Songs, and widely used in courts and government offices. In ancient times, officials were in charge of this matter and built an "ice well" to pit ice.

Song Gaocheng's "Tale of the Story" said: "There is an iceman in Li Zhou. He chisels ice with his hands to make ice. Note: Ling, ice room also. It started here. "

There are three kinds of ice depots in Qing Dynasty: official ice depots, government ice depots and merchant ice depots.

Ice cutting and ice storage activities are held on the 39th and 49th of every year 1 1 month, which is quite a grand activity.

In the Hui Dian of the Qing Dynasty, "the regulations of the Ministry of Industry and Commerce on officials' storage of ice are clear" said: "Who cuts the ice and takes it from the royal river ... In the second half of the winter of the solstice, an official of the Ministry raised her husband to cut the ice and regarded it as a five-inch square piece of ice. Wan Na Bing, five pits in the Forbidden City, 25,000 pieces of ice;

There are six ice pits outside the west gate of Jingshan Mountain, storing 54,000 pieces of ice. There are 36,700 pieces of ice stored in the outer cellar of Deshengmen, which are used for sacrifices in various altars, temples and the Forbidden City. There are two pits outside Deshengmen, storing 40,000 pieces of ice. There are two pits outside Zhengyangmen, which store 60,000 pieces of ice for the public ... to make summer thick soup. "There was still this custom in the Republic of China.

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