Analysis:
Because people can make and use tools, they are separated from ordinary animals and become the only intelligent group. In the history of human civilization, it experienced a transition from the Stone Age to the Metal Age. The arrival of the metal age (including the bronze age and the iron age) has brought a new dawn to human civilization. Seven metals that are still widely used have been discovered. They are gold, silver, copper, iron, tin, lead and mercury. Let's talk about the discovery process of these seven metals and their influence on human development.
golden age
About 5000 years ago, in 3000 BC, Egypt with four ancient civilizations was established, and Cairo, the capital, was already a prosperous town. Whenever there is a market, the crowd here is bustling. At noon one day, there was a riot in a quiet and orderly town. People rush to a place. Through the dense crowd, it was found that Hill, a famous Cairo traveler, had a piece of Huang Cancan in his hand. Richir said that this is a treasure given to mankind by God, and he called it gold. Soon, all the people who owned gold in Cairo became rich. People are looking for gold. The beach is full of people looking for gold. At first, only a few lucky people found gold coins. Later, people noticed that some gold was mixed in the sand? Heir Qiang head ⑾ shuba? Cheng Yue, I'm afraid I'm afraid of this website. I'm afraid I'm going to pour some water on it. Does ditch media support you? Hey? Forgive?
Shortly after Richir discovered gold nuggets, he discovered silver again. One cold night, Richir and his friends chatted around the campfire. The next day, just as they were about to leave, Richir lit the fire. He is a cautious traveler. Before he leaves, he always checks his place so as not to lose anything. This time, he found nothing missing. However, a shiny thing came out of the fire and caught his attention. A great discovery happened unexpectedly. Richir found that this new metal is very similar to gold in characteristics, and it is also heavy and soft, and it will be deformed when pinched by hand. He named this metal silver. Later, people followed the method accidentally discovered by Ritschl, that is, burning silver ore with bonfires to obtain silver. This is actually a simple chemical reduction reaction. Charcoal reduces silver sulfide in silver ore to silver.
Bronze Age
1939 was the hardest year in War of Resistance against Japanese Aggression, China. At this time, an important archaeological discovery was born in the war. A Yin Dynasty giant-Simuwu Dafang Ding was unearthed in Wuguan Village, Anyang City. This big guy weighs 875 kilograms and needs twelve strong adult men to lift it, which shows that casting was not easy at that time. Simu Wuding is the largest bronze ware unearthed in the world. After testing, copper accounts for 84. 1 1%, tin accounts for 1 1.64%, and lead accounts for 2.79%. This bronze ware is the product of the heyday of bronze smelting and casting in China, and its ornamentation and structure reflect the superb technology of bronze smelting and casting in this era.
The use of copper by human beings started from pure copper instead of bronze. Archaeologists have discovered small copper devices, such as needles, beads and cones, used around 7000 BC in some areas in western Iran. The British Museum has a collection of bronze bull heads cast by Sumerians 5,000 years ago and bronze mirrors and tools made by Egyptians 3,500 years ago. In West Asia, copper ore is exposed on the surface, and people burn charcoal fire on copper ore, which will restore red copper with different color from green ore.
Pure copper is not suitable for making production tools because of its low hardness. Later, people consciously mixed other ores to make copper alloy when refining copper ore to improve the hardness of tools. In China, the famous rule of "Six Qi" is recorded in the pre-Qin ancient book Kao Gong Ji, that is, the Six Classics of Bronzes. This formula stipulates the different uses of bronze caused by different proportions of copper and tin, and its essence is different proportions and different hardness. According to archaeological speculation, people can already make pure lead and pure tin at this time. Pure lead products such as lead Jue, lead Ge and lead Hu have been found in Shang tombs.
Lead is a heavy metal, so lead and its compounds are toxic, and the ancients began to suffer because they didn't understand this. The ancient Romans used to like to use lead pipes. Archaeology found that the ancient Romans often had black lead sulfide spots on their bones, which was a chronic poisoning caused by the use of water in lead pipes. Later, people gradually realized this and stopped using lead utensils as eating utensils.
Tin has been used to wrap utensils since ancient times because of its good ductility, not easy to oxidize at room temperature and easy to make into thin sheets. Several pieces of bronze helmets with tiger faces from the Yin Dynasty were unearthed in China. One of them is very complete, and the copper inside is quite complete. The outside is plated with a thick layer of tin, which is exquisite and still as bright as new. This shows that people at that time not only realized the beauty of tin layer, but also prevented corrosion. Pure tin utensils are not preserved because tin is very afraid of cold, and once the ambient temperature is lower than 13℃, it will become powdery gray tin. This phenomenon is called "tin plague".
Iron Age
Man's earliest understanding of iron came from meteorites falling from the sky. Egyptians call it "Iron Field", and there is an interesting legend among some nomadic tribes in West Asia. They said that since iron fell from the sky, the sky must be a big iron plate. It is found that the hardness of iron is much greater than that of copper or bronze. Although it is said that iron only exists in the sky, there are still some young people who try to find iron on the earth without following the teachings of their ancestors. Around 2200 BC, Hittites in West Asia were able to smelt and use iron. BC 1290, the king of Egypt wrote a letter to the Hittite king, asking for some iron. The Hittite king wrote back and promised to provide him with a steel sword, but asked for gold in exchange. It can be seen that iron was still a precious metal at that time. King Hittite also boasted in his letter: "In our country, iron is as common as dust."
In the early ironmaking technology, solid reduction method was often used. During smelting, iron ore and charcoal are stacked layer by layer in the iron smelting furnace, which is ignited and burned to produce carbon monoxide, thus reducing iron oxide in iron ore to elemental iron. Early iron is an alloy containing a lot of carbon and oxygen impurities, which is called "evil gold" by the ancients because of its poor performance due to low melting temperature. When China was making steel in the early days of liberation, the "earth blast furnaces" in many places couldn't reach the temperature, resulting in a lot of worthless "evil gold". Later, people gradually discovered the method of improving the furnace temperature and refining pig iron with better performance, and then invented the method of "softening" pig iron by annealing to obtain low carbon steel. Later, people further invented the smelting method of wrought iron and steel, and iron was widely used in production.
Mercury and alchemy
Seven metals have brought new dawn to human civilization, but it is these seven metals that have plunged mankind into a mysterious situation. The ancients naively thought that there were only seven kinds of metals in the world. They believe that metals originated from mercury and sulfur. In fact, mercury is a silvery white liquid metal, which is similar in color and appearance to silver. Copper, iron, tin and lead can be dissolved in mercury to form an alloy similar to gold, silver and amalgam. When mercury combines with sulfur, it will produce yellow mercury sulfide, similar to gold.
Based on these characteristics of mercury and metals, people also realize that mercury compounds are not gold and silver. Alchemists believe that there should be a special way to change cheap metals such as copper, iron and tin into precious metals such as gold and silver. They say that the secret of transformation is something called the "sorcerer's stone", but for thousands of years, the "sorcerer's stone" is only an illusion of alchemists, and no one has found such a thing. Russian scholar Morozov wrote a poem called Seven Metals to describe the alchemist's thoughts. The translation of this poem is as follows:
The world consists of seven metals.
The universe, she gave it to us.
Copper, iron, silver, tin, lead and gold
The father of all metals is sulfur.
Mercury is their mother.
This alchemy, which is called "chemical germination" in the history of science, has accumulated some data for the development of chemistry, but because they are far away from life and practice and blindly rely on logical reasoning, this scientific exploration has failed. Until the 1990s, many people in China still had some naive illusions about science, which gave some scientific swindlers an opportunity. The perpetual motion machine in the 1980s and the "changing water into oil" in the 1990s were all obvious scientific scams. From history to reality, it is well explained that science cannot be based on fantasy, but only on experiments under the guidance of correct theories.