1. In ancient times, if people wanted to purify crude salt, they usually dissolved it in clear water first, then filtered and boiled it to get purified salt, but the purified salt at that time was not as fine as it is now.

There is a saying that ancient people did not master the technology of purifying salt for a long time, and it was not until the end of Song Dynasty that people began to skillfully purify sea salt and mineral salt.

3. Salt is an indispensable thing in our life. It can provide necessary substances for our body, but eating too much is also harmful to our body, so we must control the amount of salt when cooking.