In the center of the concave surface of the chestnut, pinch it horizontally with your thumb, and there will be a small mouth on it. Press your hands up and down on both sides of your mouth, and the shell will open a little. The shell is gone, and now it's time to remove the hard skin inside. Put the shelled chestnuts into this bowl, pour in boiling water and salt, cover and stew for 5 minutes, and peel them after opening. The principle is that there is a fiber connection between the nut and the peel of chestnut, and the gap between them is very small, only ionic substances can enter and separate. However, there are few ionic substances in clean water, while salt can be completely dissolved in water, and its components, sodium ions and chloride ions, can enter between nuts and pulp to separate them.