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Black powder is one of the greatest inventions of the Chinese

▲Black powder

The fully-developed black powder is composed of three materials and grinds to powders (potassium nitrate, sulfur, charcoal) in right proportion.

Potassium nitrate decomposes into oxygen when heated. Sulphur and charcoal then are burned rapidly with the released oxygen resulting large amount of gas and heat. This is the chemical reactions of black powder.

▲Black powder firecrackers

Fully-developed black powder has along history of development.

In the Qin（221 to 207 BC）and Han（202 BC to 220 AD）Dynasties, both nitrite and sulfur belonged to some kind of medicine, and their medical properties were described in detail in a book Shennong Herbal Classic（Writing time is EasternHan Dynasty（25 to 220 AD））.

▲potassium nitrate

From the Three Kingdoms（220 to 280 AD）to the Southern and Northern Dynasties（420 to 589 AD）, alchemy was very popular.

▲sulfur

Smelting materials for alchemy include minerals and plants. Potassium nitrate and sulfur were also commonlyused.

For example, in a alchymists’s book, wrote by Ge Hong, such materials as nitrates, pig's intestine and pine resin were used to mix with artificial realgar to form a medicine for longer life.

▲charcoal

Alchemists would mix all these materials and do the heating. Nitrate and sulphur are flammable substances. When these mixed materials were heated, they tended to explode. In the process of alchemy, alchemists gradually realized this property.

In order to avoid explosion, thealchemists of Tang Dynasty （618 to 917 AD）would pretreat the mixed materials before heating process, which was called 'FUHUO'. The most important step of'FUHUO' was  heating up themixed materials gently. By doing that the mixed materials will be oxidised, and thus explosions would not be easily occur during the later alchemy heating upprocess.

▲The police in Langzhong was destroying the illegal black powder they had confiscated.

Since 'FUHUO' including the heat up process, it is dangerous to operate improperly. In a alchemy book named Zhen Yuan Miao Dao Yao Lue（Written in the late Tang Dynasty（618 to 917 AD） or the Five Dynasties（907 to 960 AD）, which record that ahouse was burnt down while someone was doing the 'FUHUO' process in the treatment of the mixture of sulphur, realgar, honey and nitrite.

It is now impossible to know the exact time of the black powder was invented. The word 'gunpowder' was first found in a military book named WuJing Zong Yao in the Northern Song Dynasty（960 to 1127 AD）. But the use of gunpowder weapons were probably began in the late Tang Dynasty（618 to 917 AD）.

▲Qing Dynasty Black Powder as Propellant For The Guns

During the period of Tang Zhaozong （867 to 904 AD）, general YangXingmi's army attacked Nan Chang (southern China province) and where he used'flying fire' to destroy a city gate named Longsha. 'Flyingfire' was some kind of gunpowder weapon,  such as cannon（At that time, the ' cannon ' was an incendiary bomb thrown by a lithotripter.）or rocket（The 'rocket' at that time was an arrow withburning objects tied to it.）, according to the military book named Hu Jin Jing, written by Xu Dong in the Northern Song Dynasty（960 to 1127 AD）.