Gunpowder, as the name suggests, is a medicine that can ignite, and its main characteristic is that it ignites when it is touched. So why is it called "medicine"? Because the two main ingredients in the manufacture of gunpowder, nitrate and sulfur, are both medicines, it is called gunpowder. Unlike substances that rely on oxygen in the air for combustion, gunpowder is a self-oxygen combustion system in which oxygen is released from saltpeter to complete the combustion process, so it can be burned in a closed container. It can be seen that saltpeter plays the role of an oxidizing agent in gunpowder. Sulfur plays the role of a reducing agent in the combustion of gunpowder and is an important factor for gunpowder to explode.

In the late Spring and Autumn Period (the sixth century B.C.), there was a person named Ji Ran who said: "Shiliu Huang out of Hanzhong" and "Stone out of Longdao". Stone flow yellow is sulfur; Eliminated stone is saltpeter, in ancient times also called flame nitrate, fire nitrate, bitter nitrate, frost and so on. It can be seen that as early as the Spring and Autumn Period and the Warring States Period, charcoal, sulfur, and saltpeter have been well known to people. In the "Shennong's Materia Medica" of the Han Dynasty, the first classic of medicinal materials in China, saltpeter and sulfur are listed as important medicinal materials. Even after the invention of gunpowder, gunpowder itself was introduced into the class of medicines. In the "Compendium of Materia Medica" written by Li Shizhen, a famous medical scientist in the Ming Dynasty, it is said that gunpowder can cure sores and ringworm, kill insects, and dispel dampness and plague

Gunpowder was invented by the Lian Dan family. From the Han Dynasty to the Tang Dynasty, after a long period of exploration and bold experiments, although the Lian Dan family did not achieve the purpose of practicing the "elixir", they invented gunpowder in the process of refining the "elixir".

First of all, there is a certain understanding of the properties of the three components that make up gunpowder. As early as the Shang and Zhou dynasties, charcoal was widely used in metallurgy. In practice, it has been learned that charcoal is a better fuel than firewood. Sulfur is naturally occurring, and people have mined it for a long time. At the same time, the pungent sulphur dioxide escaping from the smelting process and the sulphur gas overflowing from the hot springs directly stimulate people's senses. It was during these exposures that some of the properties of sulfur were gradually recognized. In addition to its special effects on certain skin diseases, there are also certain peculiar properties. For example, in "Shennong's Materia Medica", it says: "Stone sulfur...... It can turn gold, silver, copper, iron, and strange things. "That is, sulfur can be combined with metals such as copper and iron. In the "Zhou Yi Shen Tong Deed", the earliest alchemy book in China, the Eastern Han Dynasty, recorded the reaction of sulfur and mercury to form red mercury sulfide. These properties of sulfur are highly valued in the eyes of alchemists. Sulfur can not only combine with metals such as copper and iron, but also subdue the magic of mercury. Therefore, the practitioners often use sulfur in their vain attempt to refine the so-called "gold liquid" and "return the Dan" with mercury. In experiments, it was also found that sulfur is easy to fly when ignited, and it is very difficult to catch it. How can we make it easier to control when it is mild? The practitioners used a method called the "volcanic fire method", which is to denature it by mixing it with some other flammable substance or burning it to some extent. The invention of gunpowder is closely related to the experiments of this type of sulfur fire. The introduction of nitrate is the key to the production of gunpowder. The chemical properties of nitrate are very lively, and when sprinkled on red charcoal, fireworks are immediately generated, which can interact with many substances, so in alchemy, nitrate is often used to change the properties of other medicines. At the same time, there are many ways to ambush fire saltpeter. And because the color of saltpeter is not much different from some other salts such as sodium sulfate, it is easy to make mistakes in use, so people have also mastered the method of identifying saltpeter. Tao Hongjing, a pharmacist in the Northern and Southern Dynasties, pointed out in the "Commentary on the Materia Medica": "If you burn it with fire, the purple and green smoke rises, and the cloud is saltpeter." "This is similar to the modern use of flame color reaction to identify potassium nitrate. This made the technical preparation for the later mass use of saltpeter.

The understanding of the properties of carbon, sulfur, and nitrate prepared the conditions for the invention of gunpowder. In the rising stage of China's feudal society, due to the development of medicine and alchemy activities, especially through long-term practice, people have observed in many experiments of fire sulfur and fire saltpeter that the mixture of ignite saltpeter, sulfur and charcoal will be burned extremely fiercely.

In 682 A.D. (the first year of Yongchun of Tang Gaozong), the Tang Dynasty Lian Dan family pioneered the sulfur fire method, and in the fifth volume of the "Zhujia Shen Pin Dan Law", there is a "Sun Zhenren Dan Jing Inner Sulfur Method": take two taels of sulfur and saltpeter, grind them into powder, and put them in a silver pot or sand pot. Dig a pit and put pots in the pit and on the ground, and fill it with earth on all sides. The three soaphorns that have not been eaten by insects are lit one by one, and then they are sandwiched into the pot and the sulfur and saltpeter are set on fireworks. When the fireworks can't be burned, fry the charcoal again, fry until the charcoal is gone, then anneal, and before it has cooled, take out the mixture, and this will ambush the fire. From this account, it can be seen that at that time, it was understood that the ignition of a mixture of nitrate, sulfur, and carbon would react violently, and measures were taken to control the reaction speed and prevent explosions.

In 808 A.D. (the third year of Tang Xianzong's reign), he created the "Fuhuo Alum Law". Similar experiments also appear in the second volume of the "Lead-Amalgam Heptane Zhibao Collection" in the middle of the Tang Dynasty. There was a man named Qing Xuzi, who said when talking about the "Fuhuo Alum Method": "Two taels of sulfur, two taels of nitrate, and three and a half coins of aristolochia." The right is the end, mix well. Dig a pit and put the medicine in the tank and the ground. Put a piece of cooked fire, the marble is big, put it inside, the smoke gradually rises, cover it with four or five layers of wet paper, use a square brick piece to poke it with a mound of earth, wait for it to be cold and take it out, and its sulfur is subdued. "In this experiment, the wild plant Aristolochia, like the soaphorn in the above experiment, was burned instead of charcoal. Care is also taken to prevent intense combustion of the mixture. Such an operation method is a summary of experience after repeated practice.

The above two formulas, mixed with the three medicinal materials, have preliminarily possessed the ingredients contained in gunpowder, which are theoretically similar to the equation of 2KNO2+S+K2S+3CO2↑+N2↑+Q. However, the medicinal materials used are natural products, not refined, and the texture is neither pure nor standard, so the power of gunpowder is still weak.

Lessons about failure are also documented. Written around the time of the Five Dynasties (10th century AD), an alchemy book called "The Essentials of the True Yuan Miaodao" warned that if you combine sulfur, saltpeter, male sulfur (As2S2) and honey and burn them together, fireworks will occur, burning people's faces and hands, and they can also go straight to the house and burn the house. It can be seen that people are already familiar with the combustion and explosion properties of such mixtures, and they are prevented in alchemy. People consciously took advantage of this property of such mixtures, and gunpowder was mastered.

After continuous improvement by alchemists, around the late Tang Dynasty (the end of the ninth century), the invention of black powder in China officially appeared. Gunpowder, which was invented at that time, is now called *; Because of its brown color, some people call it brown gunpowder. It is a mixture of three powders, potassium nitrate, sulfur, and charcoal. This mixture is extremely flammable and quite intense to burn. This is because potassium nitrate is an oxidizing agent that releases oxygen when heated. Sulfur and carbon are susceptible to oxidation and are common reducing agents. When they are mixed and burned, the redox reaction proceeds rapidly, releasing high heat and producing a large amount of gas. If the mixture is wrapped in paper, cloth, skin, or stuffed in a clay pot or stone hole, and when burned, the volume suddenly expands and increases to several thousand times, and the explosion will occur. This is the principle of * incendiary explosion.

Like other inventions, the invention of gunpowder has also undergone a long process of practice and understanding, and has been gradually perfected with the development of production and the progress of society.

After gunpowder was applied to the military, it gradually developed and improved in manufacturing technology and performance. During the reign of Renzong of the Northern Song Dynasty (around 1040 AD), the military work Zeng Gongliang, who was known for his familiarity with allusions to laws and regulations, wrote the first volume 12 of the military work "Wujing General Essentials", which already recorded in detail the preparation methods of cannon gunpowder, tribulus terrestris gunpowder, and poisonous smoke gunpowder.

Forty taels of flame nitrate, fourteen taels of sulfur, fourteen taels of charcoal, plus bamboo ru, hemp ru, clear oil, tung oil, sulfur wax, dry paint, arsenic, sulfondan, fixed powder, thick oil, etc. The proportion of nitrate is 50.6%, sulfur 26.6% and charcoal 22.8%.

Tribulus terrestris gunpowder uses 40 taels of flame nitrate, 20 taels of sulfur, 5 taels of charcoal, plus bamboo, hemp, small oil, tung oil, asphalt, sulfonous wax, dry paint, etc. Its composition ratio is 50% nitrate, 25% sulfur and 25% charcoal

Thirty taels of flame nitrate, fifteen taels of sulfur, five taels of charcoal, plus croton, *, wolf poison, grass aconitum, sulfur wax, bamboo ru, hemp ru, small oil, tung oil, asphalt, etc., the composition ratio is 49.06% nitrate, 24.8% sulfur, and 25.6% charcoal;

The above three gunpowder formulas show that saltpeter, sulfur, and charcoal are used as basic raw materials, and then mixed with some other substances, gunpowder with different properties and uses can be formulated. These three formulas are not only excellent stereotyped products after Song Jun's trial and transformation, but also samples of gunpowder prepared in various places. The ratio of nitrate, sulfur and carbon is gradually becoming reasonable.

However, compared with modern black gunpowder, there is still a certain gap in the composition rate of these three gunpowders (the standard formula of modern black gunpowder: 75% nitrate, 10% sulfur, and 15% charcoal), because the content of oxidant saltpeter is too low, the oxygen supply is insufficient, the content of combustible sulfur with low melting point is too much, and it is mixed with many other ingredients, and its performance only has the effect of arson, poison dispersion and smoke. The "Thunderbolt Fireball" contained in the "Wujing General Essentials Collection" is made according to the first formula mentioned above, and it is not an explosive firearm, named Thunderbolt, because the bamboo pole bursts after the gunpowder, making a loud noise, and because the bamboo pole bursts, the red-hot porcelain pieces in the sphere are scattered nearby, which can hurt people, so it is said that it has the germ of an explosive firearm.

It can be seen that the gunpowder in the early Northern Song Dynasty has developed considerably on the one hand, and on the other hand, the formula composition is also very complex, and it is still a low-grade gunpowder. The "thunderbolt cannon" and "iron artillery" that appeared at the end of the Northern Song Dynasty must have been gunpowder with explosive properties.

In the Song and Yuan dynasties, various firearms appeared on the battlefield, and their applications became more and more extensive. The demands of war led to the continuous improvement of the properties of gunpowder. By the Yuan Dynasty, the content of nitrate in the gunpowder formula had increased significantly, reaching 60%, and sulfur and charcoal accounted for about 20% each. The manufacturing process has also been improved, impurities have been reduced, and the slow-burning substances in the gunpowder have been eliminated, and the finished products are mostly granular, which has great power.

By the Ming Dynasty, the development of gunpowder had made great progress and reached a higher level. Written in the early Ming Dynasty, the "Fire Dragon Artifact Formation" recorded a variety of gunpowder formulas, and proposed that "it is necessary to know the appropriateness of medicinal properties" in order to "get the magic of fire attack", which has been a great development compared with the "General Essentials of the Martial Arts". Qi Jiguang wrote in 1560 A.D. (the 39th year of Jiajing) in the "Illustration of the Instruments of Putrajaya", the formula and manufacturing process of gunpowder used to launch guns are recorded in more detail. Its formula is "one tael of nitrate, one penny and four cents of sulfur, and one coin and eight cents of willow charcoal", which is 75.75% of saltpeter, 10.6% of sulfur and 13.65% of charcoal, and the standard composition rate of modern black gunpowder has been basically the same.

Traditional gunpowder formulas with different composition ratios are often recorded in the "Armed Weapons Law". Among them, the gunpowder formula used for rocket meteors and soaking lines is "one-sixth sulfur nitrate, one-fifth carbon nitrate, and the converted composition ratio is 73.2% sulfur nitrate, 12.2% sulfur and 14.6% charcoal." The formula of explosives is "one-third or one-quarter sulfur nitrate, and one-quarter of charcoal nitrate, and the converted composition ratio is 66.6% nitrate, 16.7% sulfur, and 16.7% charcoal." The formula of artillery and bird's gun* is "1/10 sulfur nitrate, the same as charcoal", and the converted composition ratio is 83.3% nitrate, 8.35% sulfur and 8.35% charcoal.

There are many formulations of gunpowder composed of homogeneous raw materials of sulfur or charcoal, which can be formulated into different gunpowders. For example, it is said in "Binglu Fire Attack Medicine", "male yellow gas is high and flame", which can prepare gunpowder with strong burning; "Shihuang gas is fierce and fiery", which can be used to prepare strong gunpowder; "Arsenic yellow is smelly and poisonous", and it can be prepared to cause poisoning agents. Another example is the "Wubei Zhi Firearms Law" that "willow ash and eggplant ash are the lightest and easy to ignite", and can prepare gunpowder that is easy to ignite; "Floating ash and honeycomb ash are light", which can prepare gunpowder that is very easy to ignite; Gourd ash can be used to prepare violently burning gunpowder, and hoop leaf ash can be used to prepare bursting gunpowder.

There are more gunpowder formulas composed of other raw materials added to gunpowder, and more than 50 are recorded in the "Characteristics of Fire Attack Medicine" alone. For example, gold needles, sand, iron, magnetic fronts and other substances are added to prepare "rotten gunpowder" that makes people's muscles rot; Add grass aconitum, croton, thunder vine, water horse and other substances to make a speechless "blood throat sealing medicine"; Add Jiangzi Changshan, Banxia, Sichuan Huang and other things to make a comatose "spewing gunpowder"; Add tung oil, soybean flour, rosin and other substances to prepare the "flying gunpowder" that burns the enemy's grain and grass and camps; Add hair, iron juice, oil and other substances to prepare a strong burning agent for burning enemy leather carts and leather tents; Add fierce fire oil and other substances to prepare gunpowder for water warfare that can burn wet matter to get more and more water; Add nine tails of fish fat and other substances to prepare an incendiary agent spread by the wind; Add wolf dung and other substances to prepare alarm fireworks that smoke during the day and glow at night; Add finless porpoise bones, finless porpoise oil, wolf dung, mugwort and other prepared "anti-wind gunpowder"; After adding indigo, lead powder, purple powder, and wood coal, it is prepared to produce alarm gunpowder that can emit green smoke, white smoke, purple smoke, and black smoke.

Later in the "Gunpowder Materials" contained in the "Jiabing Chapter" in the "Heavenly Works" published in 1637 AD, it is divided into direct gunpowder and horizontal gunpowder, which is equivalent to the concept of firing and exploding. It is said that the gunpowder that hits directly is the ratio of nitrate nine and sulfur one, and the gunpowder that strikes horizontally is the ratio of nitrate seven and sulfur three. This shows that the composition of gunpowder at this time was relatively simple, and people had a firm grasp of the combination of gunpowder for firing and gunpowder for explosion.

The preparation process of gunpowder in the Ming Dynasty has also made great progress, which mainly includes the selection, refining, preparation and inspection of raw materials.

Nitrate is the main raw material for the preparation of gunpowder, and its purity has a great influence on the power of gunpowder. The process of making nitrate in the Ming Dynasty is divided into three steps. The first step is to dissolve natural saltpeter in fresh water without impurities, and precipitate and remove granular impurities such as sediment in it. The second step is to use a certain amount of egg white, red basket and other adsorbents into the nitrate solution to boil many times to adsorb the dregs and saline-alkali and other components, and then use a fence to remove the adsorbate. The third step is to put the water glue into the nitrate solution and boil it again, and then pour the nitrate into the porcelain urn to cool and solidify, so that the waste water floats on the urn, the mud sinks to the bottom of the urn, and the pure nitrate is in the center, and finally the water is removed and the slag is removed, and the pure nitrate is taken out to dry. After the above process, every 100 catties of natural nitrate can only be refined into 30 catties of pure nitrate. This pure nitrate has white crystals.

Sulfur is a fast-burning explosive, and its purity has a great impact on the explosive power of gunpowder. The refining process of sulfur in the Ming Dynasty was divided into four steps. The first step is to mash the sulphur and remove the sand and debris. The second step is to put the mashed sulfur into a pot and boil it with fresh water to remove impurities, pour it into an urn and precipitate for a day, then remove the sediment and obtain crude sulfur. The third step is to pour 10 catties of sulfur into the ratio of 2.5 catties of butter and 1 catty of sesame oil, decoction, so that the oil is not sticky with sulfur, and then add cypress leaves to the pot and cook with sulfur to absorb the black scum in the pot. The fourth step is to put the coarse sulfur removed from the slag into boiling oil and boil, after the oil surface is covered with yellow foam, put it into a basin to cool, and finally remove the yellow foam and impurities on the surface, and take out the pure sulfur without residue and degreasing, which is lemon-colored lumpy crystals.

Charcoal powder is a combustion agent in gunpowder, and its quality can affect the combustion rate of gunpowder. When baking charcoal, it is best to choose the wicker before and after the Qingming Festival, because the wicker leaf buds at this time will not germinate, and the nutrients will be concentrated on the wicker. If the wicker with straight and uniform branches is removed, the skin is removed and the knots are removed, and then dried naturally, and then baked into charcoal and crushed into powder. The gunpowder prepared with this charcoal powder is smokeless due to the peeling of the charcoal, and the knots are removed without resin, which improves the combustion speed and isotropic uniformity, and enhances the instantaneous explosive power.

The process of preparing gunpowder consists of four steps. The first step is to put the selected and refined nitrate, sulfur and charcoal into a stone mortar or wooden trough according to the requirements of preparing gunpowder, and according to the proportion of the formula, and repeatedly pound them many times to make them fine. The second step is to mix the fine nitrate, sulfur and charcoal powder into a wooden mortar in proportion, then add a large amount of pure water or shochu, mix the mixture into a wet mud form, and pound it thousands of times with a wooden pestle. In the process of pounding, it is strictly forbidden to mix sand and gravel into the mortar, so as not to cause fire after bumping. When the mixture will be dry, add water and pound again to make the mixture fully homogeneous and delicate, and then take it out to the sun. The third step is to perform a quality check on the finished product. A part of the sun-dried gunpowder sample is selected and burned on paper, if it is quickly burned out and the paper is intact, it is a qualified product. Or put the sample in the palm of the hand to burn, and the gunpowder is burned without feeling the heat in the palm, indicating that the finished product burns quickly and is a qualified product. On the contrary, if there is a black heart and white heart on the paper after the gunpowder is burned, or the palm of the hand feels burned, it is a substandard product, and it needs to be counter-worked and crushed again until it is qualified. The fourth is to screen qualified medicine grains, Zhao Shizhen wrote in 1598 A.D. (the twenty-sixth year of Mingshenzong Wanli) in the "Artifact Spectrum" said: gunpowder particles, "coarse ones do not use, fine ones do not use, stop taking those like corn into the gun", indicating that the relationship between the size of gunpowder particles and the burning speed of gunpowder at that time has a deep understanding. The medicine blocks that have passed the inspection are broken into granules, and the large, medium and small gunpowder particles used in the large guns (cannons), Franc machines and bird guns are screened out respectively with different coarse and fine co-sieves, and the non-granular ones can be used as the ignition powder of the fire door, and the remaining fine powder is all removed. The purpose of selecting the corresponding grade of granular gunpowder according to the caliber of the gun and the size of the chamber is not only to increase the firing power, but also to ensure the safety of firing.

The development of firearms in ancient China has gradually declined since the beginning of the 18th century, and the gunpowder used by the Qing Dynasty before the First * War is still generally prepared according to the theory and technology of gunpowder preparation in the Ming Dynasty, using manual operation methods. At the same time, the industrial revolution in the West greatly promoted the development of gunpowder and firearms technology.

After the defeat of the Qing army in the First War, some commanders and gunpowder developers of the Qing Dynasty discovered the shortcomings of the old gunpowder. In order to improve the performance of gunpowder, a large number of tests to improve the preparation process were carried out, and the number of refining nitrate was increased from one to three times, and then according to the ratio of 8 catties of nitrate, 1 catty of sulfur powder and 2 taels, and 1 catty of charcoal powder and 6 taels, they were placed in a stone mortar, and pounded thousands of times with a solid wooden pestle made of Huai elm wood, and the composition ratio was 76% nitrate, 10.7% sulfur, and 13.3% charcoal. After comparative testing, the performance is basically the same as that of the British army*.

After the invention of gunpowder in ancient China, it was constantly improved and improved in military use. The law of its development is: the preparation from no strict proportion to a certain proportion; The ingredients are complex to simple and pure; The shape ranges from powder to granules. The combustion, explosion and firing properties of gunpowder have also been gradually applied to firearms.