The blackening of lead acetic acid paper
There is a strange thing in the world, called lead acetic acid paper. Its quality is special, and when it encounters a certain gas, it turns black in an instant, and everyone is different.

There is a sorcerer who puts lead acetic acid paper in a secret room. The charcoal fire in the furnace is booming, burning something, and suddenly, the smoke rises. The lead acetic acid paper touches the smoke and gradually dyes black, like ink pouring, evenly and quickly.

Everyone is confused, why is the paper black when it encounters this smoke? Or: "This smoke contains something, which combines with lead acetic acid paper, so it changes color." However, it is unknown whether it is true.

There are also good researchers who want to find out the reason. Examine the composition of the smoke and analyze the material of the paper. After many tests, it is known that the sulfur in the smoke, the sulfur and the lead in the lead acetic acid paper combine, resulting in black things, causing the paper to turn black.

Since then, everyone knows the reason why lead acetic acid paper turns black, and it is also clear that things touch and change thousands of times. It is reasonable to follow, not for no reason.