What is the earliest composition of gunpowder in China?

China is the first country to invent gunpowder in the world, and it has been 1000 years since our ancestors invented gunpowder. The gunpowder invented at that time is now called "black gunpowder". Because it is brown, some people call it "brown powder". This kind of gunpowder is a mixture of potassium nitrate, sulfur and charcoal, which is very easy to burn. If it is wrapped in paper, stone, pottery and tin cans, the volume of gunpowder will suddenly expand thousands of times when it burns, so it will explode.