Saltpeter ice making method.

The saltpeter ice making method was first seen in the Tang Dynasty. As mentioned earlier, the population increased dramatically in the Tang Dynasty, and the method of storing ice was far from being able to meet people's summer needs. Therefore, a new method was needed to increase the amount of ice.

In the process of mining gunpowder, people at that time accidentally discovered that when saltpeter is dissolved in water, it will quickly and massively absorb heat in the water, and it can also make the water freeze. Therefore, saltpeter was made. Ice method.