In contemporary times, ice cubes are commonplace, and many people may feel that there are no secrets left to speak of. But how did people in the past obtain ice cubes, and where did refrigeration technology come from?
The early written records of ice preservation should have come from China. In the late Spring and Autumn period, there were records of taking ice from the "cellar" and adding rice wine for drinking. The so-called "cellar" is also known as an ice cellar. Because most human settlements in ancient China had distinct seasons, during winter when lakes and rivers froze, people would extract ice from them and store it in ice cellars. Take it out and use it in the hot summer.
And it was also China that initially invented ice making technology. As early as the Tang Dynasty, there were records of saltpeter ice making. The main component in saltpeter is potassium nitrate, which absorbs a large amount of heat when dissolved in water. At that time, people used this feature to make ice cubes. And modern air conditioning and refrigeration, as well as ice making technology, originated from the Americas in the mid-19th century. At that time, a doctor invented the initial air conditioning system by using a steam engine as the power source to provide cold air for his high fever patients, utilizing the physical principle that air expands and absorbs heat. Later on, the doctor did not rely on this invention to develop a new industry, but this idea was carried forward by other engineers, and another French engineer developed a more complete refrigerator. So during the Northern and Southern periods in the United States, this invention achieved great development due to the sealing of ice transportation from the North to the South. From then on, humanity entered the era of large-scale refrigeration.