The smelting technology in ancient my country was quite developed. As early as the Yin and Shang Dynasties, large bronze vessels with complex shapes and beautiful appearance could already be produced. In the middle of the Spring and Autumn Period, my country had invented pig iron smelting technology. By the late Spring and Autumn Period, iron farm tools and weapons had also been widely used.
In the process of smelting metals, people constantly sum up their experience, gradually come into contact with and become familiar with the properties of many minerals, and accumulate a wealth of chemical knowledge. Since the Warring States Period, some people have applied metallurgical technology to refining medicines, dreaming of refining the elixir of immortality, while others want to refine gold and silver from minerals. The alchemy technique of refining the so-called elixir of life was called "alchemy" in ancient times, and the alchemists who engaged in alchemy were called "alchemists", and later they were called "Taoist priests" or "alchemists".
Although these alchemists have never been able to refine the elixir of immortality, they have continuously accumulated experience and mastered a lot of chemical knowledge through smelting. These alchemists played a great role in the development of ancient chemistry in my country. From a modern perspective, it may be more appropriate to call them ancient chemists. Among these alchemists, the more prominent ones include Li Shaojun, Wei Boyang, Liu An, Ge Hong, etc. It was the work of these alchemists that led to the discovery of gunpowder.
Now we know that the main raw materials for making gunpowder are charcoal, sulfur and saltpeter. Sulfur was also called stone sulfur, yellow sulfur, sulfur, etc. in ancient my country. Our ancestors discovered a large amount of sulfur mines in Chenxian County, Hunan around BC. Since then, large sulfur deposits have been discovered many times in northern and southern my country. The earliest mention of "sulfur" in ancient Chinese books is the book "Huainanzi" (around 150 BC).
This shows that the ancients already knew about sulfur at that time. my country's first medicinal classic, "Shen Nong's Materia Medica", which came out at the end of the Western Han Dynasty, classified lime sulfur as the third type of "traditional Chinese medicine", which shows that sulfur was widely used in medicine at that time. Saltpeter is the oxidizing agent in black gunpowder. Its chemical component is potassium nitrate, which can produce oxygen when heated and has a strong combustion-supporting effect. The explosive power of gunpowder is mainly determined by the nitrate content.
At the latest before BC, our ancestors had discovered saltpeter and were able to master and utilize it. In practice, ancient people gradually discovered that saltpeter had medical effects such as eliminating accumulated heat and blood congestion, so they used it as medicine. "Shen Nong's Materia Medica" lists saltpeter as the sixth type of "top-grade medicine". Ancient alchemists were very familiar with the properties of saltpeter and often used it as the main oxidant and solvent. Around 500 AD, the alchemist Tao Hongjing pointed out that saltpeter has the phenomenon of "violet and green smoke rising when it is strongly burned."
In the early years of the Tang Dynasty, the famous pharmacologist Sun Simiao also refined elixirs. In the "Alchemy Classic" written by him, there is a "sulfur method", which records a recipe similar to gunpowder. Since this method of sulfur immersion often burns during the production process, burning the alchemist's hands and face, and even burning down the alchemy room, the ancients understood that the mixture of sulfur, saltpeter and charcoal can easily catch fire violently and even explode during production. Must be very careful.
After repeated explosions and fires, alchemists gradually realized from their initial fear that sulfur, saltpeter and charcoal, if prepared in a certain proportion, can make explosive "gunpowder". The specific age of the invention of gunpowder is unknown, but based on the data it can be inferred that the invention of gunpowder should be before the Tang Dynasty. Because the color of this gunpowder is black, it is called "black powder".