Category: Education/Science>>Science and Technology
Analysis:
Human beings are separated from ordinary animals because they can make and use tools, and become unique intelligent group. In the history of the development of human civilization, it has 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) brought a new dawn to human civilization. People discovered seven kinds of metals that are still widely used today. They are gold, silver, copper, iron, tin, lead, and mercury. Let’s talk about the discovery process of these seven metals and their impact on human development.
Golden Age
About 5,000 years ago, that is, in 3000 BC, Egypt, one of the four ancient civilizations, had been established, and its capital, Cairo, was already a prosperous town. Whenever I go to the market, the crowd here is bustling. One day at noon, a riot broke out in the quiet and orderly town. People rushed to a place. Through the dense crowd, people found that the famous Cairo traveler Richier was holding a piece of yellow stuff, Richie. You said this was a treasure given to mankind by God, and he called it gold. Soon, everyone in Cairo who owned gold became rich. People went looking for gold one after another. The sand on the river beach was filled with people looking for gold. At first, only a few lucky people found nuggets of gold. Later, people noticed that there was some gold mixed in the sand. To Shu Ba? Cheng Yue Zhen Ba Mu Jiao ā: Exhausted Ci Si timid site ⑾ to the ground like a drop of earthworm? Repair pouring corvette Mu Jiao ǎ? Ditch media shear support Mou? Carrying? Shu Shu?
Just Not long after Rihir discovered the gold nugget, he discovered silver. One cold night, Richiel and his companions chatted around a campfire. The next day, just as they were about to set off, Richie pulled a fire. He was a careful traveler. Before every departure, he always checked where he lived to avoid losing anything. This time he checked Not only did he not find the missing things, but some shiny things pulled out of the fire caught his attention, and a great discovery was made unexpectedly. Richie found that the properties of this new metal were very similar to gold. It was also heavy and soft, and could be deformed by pinching it with hands. He named the metal silver. Later, people followed the method accidentally discovered by Richier, that is, burning silver ore in a campfire to obtain silver. This was actually a simple chemical reduction reaction. The charcoal reduced the silver sulfide in the silver ore into silver.
The Bronze Age
1939 was the most difficult year of my country’s Anti-Japanese War. At this time, an important discovery in the archaeological world was born in the war. It was unearthed in Wuguan Village, Anyang City. A behemoth of the Yin Dynasty was created: the Simuwu Dafang Ding. This big guy weighs 875 kilograms and requires twelve strong adult men to lift it, which shows that it was not easy to cast at that time. The Simuwu Ding is the largest bronze vessel unearthed in the world. After testing, copper accounted for 84.11%, tin accounted for 11.64%, and lead accounted for 2.79%. This bronze is a product of the heyday of bronze smelting in my country. Its decoration and structure reflect the superb bronze smelting technology of this era.
Humanity’s use of copper began not with bronze but with pure copper. Archaeologists have discovered small copper devices, such as small needles, beads, and cones, used before about 7000 BC in some areas of western Iran. The British Museum has a collection of bronze bull heads cast by the Sumerians 5,000 years ago and bronze mirrors and bronze tools made by the Egyptians 3,500 years ago. In West Asia, copper ore is exposed on the surface. When people burn charcoal on the copper ore, red copper that is different from the green ore will be restored.
Due to the low hardness of pure copper, it is not very suitable for making production tools. Later, people consciously mixed other ores when refining copper ore to make copper alloys to improve the strength of tools. hardness. In our country, the ancient pre-Qin book "Kaogong Ji" records the famous "Six Qi" rules, which are six formulas of bronze. This set of formulas stipulates the different uses of bronze made of different proportions of copper and tin. Its essence It's the different proportions and different hardnesses. According to archaeological speculation, people were already able to produce pure lead and pure tin at this time. From the tombs of the Shang Dynasty, pure lead products such as lead jue, lead Ge and lead dendrobium have been discovered.
Lead is a heavy metal, so lead and its compounds are toxic. The ancients began to suffer a lot because they did not understand this. The ancient Romans liked to use lead water pipes. Archeology has found that the bones of ancient Romans often had black lead sulfide spots. This was chronic poisoning caused by using water from lead pipes. Later, people gradually realized this and no longer used lead utensils as eating utensils.
Tin has been used to wrap utensils since ancient times because of its good ductility, which makes it easy to make thin sheets and is not easily oxidized at room temperature. Several tiger-faced bronze helmets from the Yin Dynasty have been unearthed in our country. One of them is very complete. The internal red copper is quite intact. The outside is plated with a thick layer of tin. The tin layer is exquisite and is still as bright as new. This shows that people at that time realized that the tin layer was not only beautiful, but also anti-corrosive. No pure tin ware has been preserved. This is because tin is very sensitive to cold. Once the ambient temperature falls below 13°C, it will undergo a phase change and turn into powdery gray tin. This phenomenon is called "tin epidemic".
The Iron Age
Humanity’s earliest knowledge of iron comes from meteorite iron falling from space. The Egyptians called it “celestial iron”, and there is also a saying among some nomadic tribes in West Asia. There is an interesting legend. They say that since iron fell from the sky, then the sky must be a big iron plate. People found that iron is much harder than copper or bronze. Although it is said that iron can only be found in the sky, there are still some young people who do not follow the instructions of their ancestors and try to discover iron in the world. Around 2200 BC, the Hittites in Western Asia were already able to smelt and use iron tools. In 1290 BC, the King of Egypt sent a letter to the Hittite King asking for some iron. The Hittite King replied and promised to provide him with a steel sword, but asked for gold in exchange. This shows that iron was still a precious metal at that time. The Hittite king also boasted in the letter: "In our land, iron is as ordinary as dust."
Most of the early iron smelting technologies used the solid reduction method. During smelting, the iron ore was Stone and charcoal are stacked layer by layer in an iron-making furnace and ignited to burn, producing carbon monoxide, which reduces the iron oxide in the iron ore to elemental iron. Early iron had poor performance due to its very low smelting temperature. It was an alloy containing a large amount of carbon and oxygen impurities, which the ancients called "evil gold." When my country was engaged in large-scale steel smelting in the early days of liberation, many local "earth blast furnaces" could not reach a temperature that allowed them to produce a lot of worthless "evil gold." Later, people gradually discovered ways to increase the furnace temperature to produce better-performing pig iron, and then invented the annealing method to "soften" pig iron to obtain low-carbon steel. Later, people further invented the smelting methods of wrought iron and steel, and iron was widely used in production.
Mercury and Alchemy
The seven metals have brought a new dawn to human civilization, but it is also these seven metals that have plunged mankind into a mysterious situation. The ancient People naively believe that there are only these seven metals in the world. They believe that the metal originated from mercury (the common name of mercury) and sulfur. In fact, mercury is a silver-white liquid metal with a color and appearance similar to silver. Copper, iron, tin, and lead can all be dissolved in mercury to form an alloy similar to gold and silver. ——Amalgam; mercury and sulfur combine to form yellow mercury sulfide, which is similar to gold.
Based on these properties of mercury and metals, and people also realizing that mercury compounds are not gold and silver, alchemists believe that there should be a special method that can turn cheap metals such as copper, iron, tin, etc. into precious metals such as gold. Silver, they say the secret recipe for transformation is something called the "Philosopher's Stone". However, for thousands of years, the "Philosopher's Stone" was just a fantasy of alchemists, and no one has discovered such a thing. The Russian scholar Morozov wrote a poem titled "Seven Metals" to describe the alchemist's thinking. The translation of the poem is as follows:
The world is made of seven metals
The universe, she gave us
Copper, iron, silver, tin, lead and gold
The father of various metals is sulfur
Mercury is their mother< /p>
Although this kind of alchemy, which is called "the germ of chemistry" in the history of science, has accumulated some information for the development of chemistry, because they are far away from life and practice and blindly rely on logical reasoning, this kind of science has The failure of exploration. Until today in the 1990s, many people in our country still have some naive illusions about science, which gives some scientific liars a chance to succeed. The perpetual motion machine of the 1980s and the "water-to-oil" phenomenon of the 1990s are obvious scientific scams. From history to reality, it is well illustrated that science cannot be based on fantasy, but can only be based on experiments under the guidance of correct theories.