Live in the contemporary era, ice is commonplace, many people may feel no secret at all. But how did the people of the past acquire ice and where did the refrigeration technology come from?
The earliest records of the preservation of ice should be from China. In the late Spring and Autumn period, there is records that people took ice from the "cellar" to add to drinks. The so-called "cellar", that is, the icehouse. Because most of human’s settlements in ancient China were having four distinct seasons. The lakes and rivers were frozen in winter. So people might take ice from those places. Ice would be put and preserved in the icehouse for the hot summer.
The earliest invention of ice-making technology is also emerged in China. As early as the Tang Dynasty, there are records of making ice by using saltpeter. Nitrate is the main component of saltpeter, the dissolution of potassium nitrate in water will absorb a lot of heat, when people use this feature to make ice.
The modern air-conditioning refrigeration and ice-making technology, it is derived from America in the mid-nineteenth century. At the time, a doctor developed the earliest air conditioning by using the steam engine as a source of heat to provide cold air for patients with high fever and to absorb the physics of heat through air expansion. Later, the doctor did not rely on this invention to develop a new industry, but the idea was carried forward by other engineers. Another French engineer developed a more complete cooler. In the Civil War of United States, this invention had a huge development because of the blockade of ice transport and access by the North. Since then, mankind has entered a large-scale refrigeration era.