Does the silver needle really have such a magical effect? If you accidentally left, why did the ancients enjoy this technology?
As we all know, silver (AG) is a kind of white material, which only changes from white to black in the state of silver sulfide.
In ancient times, arsenic was often used as poison because of relatively backward technology. Because arsenic is so powerful that people will die when they touch it. There is no time to save. Arsenic contains a lot of impurities, mainly sulfide. Arsenic turns black when it touches a silver needle.
For other poisons, such as aconite and love flowers, silver needles can never be detected. If people are exposed to these toxic substances, they will not die immediately. Generally speaking, they will have a stomachache first. If they are not saved, they will die.
Therefore, due to backward technology, the ancients used silver needles to detect whether food was toxic, mainly arsenic. For other poisons, there is absolutely no way but to leave it to fate. At that time, the silver needle could detect the existence of arsenic, which naturally reduced the possibility of poisoning.
Of course, in today's society, due to the improvement of smelting technology. The sulfide content in arsenic is almost gone, so it can't be detected by silver needle. So now people don't need silver needles to test their eating habits.
But the ions produced by silver are beneficial to human body. It can kill many bacteria, accelerate wound healing, make people have no oral ulcer, and has a good fresh-keeping effect. Now many rich people eat with silverware.