What is the poisonous crane top red that the ancients often said? Is the silver needle test useful?

Speaking of some virulence, He Dinghong is definitely indispensable, because in costume dramas, He Dinghong has always been an invisible weapon to kill people. Of course it's toxic, so there's something to try it on. In costume dramas, silver needles are used to test poison. Although this method can confirm that there is sulfide in it by blackening the silver needle, and the main component of the day lily is sulfide, so the silver needle can try the day lily, but not necessarily for other poisons.

Let's start with the red top of the river. As the name implies, we can't say that this poison is called crane top red, but it has nothing to do with cranes. Just because his raw material red arsenic sublimate looks like a touch of red on the top of a crane, the poison made from it is also called crane top red. This thing is not cheap. Generally, only high-ranking officials and nobles can afford it, but they usually flow out of the palace. Only some powerful people will use this poison.

Red arsenic can also be made into another thing. After being colorless and tasteless, it is arsenic. When it enters the human body, it will cause some cells to die of hypoxia, and it will also stimulate some cells in the stomach to fester and bleed, and then it may lead to death. But in most cases, it still appears in the public's field of vision as a blind medicinal material.

Silver needle poison test is also the crystallization of ancient wisdom. Silver and sulfide can react to replace sulfur, which can obviously blacken the silver needle. But this method is not very accurate, because there are sulfides in eggs and other foods, so silver needles may not be particularly accurate. But at that time, it would be good to avoid a lot of poison. How can it be said that all poisons can be tested?