In ancient times, emperors mainly used the following methods to prevent themselves from being poisoned: The first method was to try a silver needle before eating to see if it would turn black. The second method is to let others eat it before eating to see if there will be any adverse reactions. The third method is to keep some royal doctors in the palace at any time to avoid emergencies. The fourth method is to strictly require the servants who cook. Some people who are unclear are not allowed to have access to these jobs.

For example, if eunuchs and slaves in a palace want to enter the palace, they must know their family backgrounds in advance. People whose identities are unclear are not allowed to enter. Palace worker. At this time, the servants considered the safety of their own families and did not dare to poison the emperor easily.

Many times, after the meal is ready, the emperor will not eat directly. At this time, the eunuch next to him will try the food first to see if he has any adverse reactions before deciding to eat. Or the servants around him would specially wear a silver needle on their body. Before the emperor eats, he would use the silver needle to test the food to see if it has turned black.