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The main uses of mercury are recorded in "Tiangong Kaiwu", which is quite detailed.
Mercury, known as mercury in ancient times, has a wide range of uses. The first is the matter of alchemy. In ancient times, alchemists often used mercury as the main medicine for alchemy. Due to the special physical and chemical properties of mercury, between the changes of the alchemy furnace, the alchemist hoped that it could refine the elixir of longevity. As the book says, alchemists used mercury and all kinds of gold stones to refine together, hoping for transformation. This is an important use of mercury in ancient times.
In addition, mercury is also crucial in the gold-plating process. In "Tiangong Kaiwu", if you want to decorate objects with gold, you first melt the gold in mercury to make a gold amalgam. Then it is applied to the surface of the utensils, and the mercury evaporates when heated, and the gold remains in the utensils to form a gilt beauty. This process can make the utensils gorgeous and brilliant, and is mostly used for the decoration of the utensils of the court nobles, showing dignity and luxury.
In addition, mercury is also used in the field of medicine. Ancient healers knew that mercury has certain medicinal effects. Although its toxicity is also known, it can be used to treat scabies, acne and other diseases after being processed. However, due to the harm of mercury toxicity, it must be used with caution when using it.
In addition, mercury also plays a role in the casting mirror industry. When casting mirrors, mercury and tin are used as agents and applied to the back of the mirror, which can make the mirror surface glow. This was the key step of casting mirrors in ancient times, which was related to the quality and imaging effect of mirrors.
To sum up, mercury was important in many aspects such as alchemy, gilt, medicine, casting mirrors, etc. It left a deep imprint on the life, craftsmanship, alchemy and other fields of ancient society.

Mercury is unique in its properties, and it is unique among all kinds of substances.
Mercury is in the shape of a liquid at room temperature, which is its remarkable physical property. Although it is a metal, it is not as hard and solid as gold and iron, but has a flowing state. It is smooth like oil and can be deformed at will. It can seep through gaps and gather in dimples.
Mercury has a metallic luster. It is silver-white and shiny, just like the condensation of moonlight. Its light is smooth but not dazzling, and it makes people feel wonderful when viewed.
Furthermore, the density of mercury is quite large, and it is abnormally heavy. It carries a large weight in a small volume, and it can often sink because of its weight.
The volatility of mercury should not be underestimated, and it quietly dissipates in the air. Although invisible and colorless, its gas is toxic. If inhaled too much, it can cause harm to the human body, damage the viscera, confusion and consciousness.
The chemical activity of mercury is also considerable, and it can react with many substances. In case of sulfur, it is synthesized into mercury sulfide. This reaction is rapid and significant, and it is often used to remove mercury damage.
And mercury has good electrical conductivity. Although it is liquid, it can also conduct electrical energy in circuits. This property makes it useful in some special electrical appliances.
The freezing point of mercury is very low, about minus 38 degrees 87 degrees Celsius, and the boiling point is 356 degrees 7 degrees Celsius. This wide temperature range is also unique, allowing it to survive in different forms and exhibit different physical properties under different temperature environments.

Mercury is very different from all things. Its substance is liquid at room temperature, silver-white and shiny, smooth and agile, like a spiritual thing.
Mercury has very good fluidity, and it is difficult to gather when it is scattered, just like mercury cascading to the ground, and it penetrates everywhere. And its density is quite large, which is heavier than that of ordinary liquids. It is placed in a vessel and remains stable.
Mercury is toxic and very harmful. If a person touches it or absorbs its volatile gas, it can cause illness. Light people are dizzy, weak, and insomnia, and heavy people damage their internal organs, endangering their lives. Ancient alchemists used mercury for alchemy, and many of them were caused by mercury poisoning.
The chemical properties of mercury are active, and it can form alloys with many metals, which is called amalgam. This property makes it widely used in metallurgy and other techniques. It can also quickly combine with sulfur to form mercury sulfide. When the two meet, they can be synthesized into a new substance. Its color is vermilion, which can be used as a pigment.
When mercury is heated, it can combine with oxygen to form mercury oxide. On the contrary, mercury oxide can be decomposed into mercury and oxygen when heated. This change is repeated, which shows the beauty of its chemistry. And there are many mercury compounds, each with its own characteristics, or with a special color, or in a unique state in chemical reactions.
Mercury has been used in ancient alchemy, medicine and utensil production, but it should be used with caution because of its toxicity. Knowing its properties, using it well and preventing its harm is the way of the wise.

There are many methods for synthesizing mercury in ancient times. In "Tiangong Kaiwu", the method of extracting mercury is mentioned.
One is the method of refining cinnabar. The cinnabar is the main ore of mercury. Take the cinnabar and place it in a special furnace tripod, and heat it with charcoal fire. The cinnabar is heated and decomposed, and the mercury is turned into steam and rises, and condensed when cold, then mercury is obtained. The book says: "Where cinnabar and mercury are the end of Dan sand, mercury is its liquid. If you want to take mercury, put the Dan sand in the retort, and force it with charcoal fire, and the mercury will rise above it, and it will be supported by the device." This process requires exquisite temperature control. If the heat is too high, the mercury will dissipate, and if the heat is insufficient, the decomposition will not be complete.
Second, lead amalgam method. Co-refining with lead and mercury-containing ores. Lead and mercury have an affinity, and the two fuse to form lead amalgam. Later, by distillation and other methods, lead and mercury are separated to obtain pure mercury. "Lead is intrinsic sedimentation, mercury is intrinsic flying, and the two are combined to refine. Lead can make mercury soaring, and lead amalgam. After further cooking, mercury will come out from itself." This process also requires a good grasp of the ratio of lead to ore and refining conditions.
Third, the method of mercury refining in bile water. In bile water, a solution containing metal salts such as copper and mercury. When active metals such as iron are put into bile water, iron and mercury salts undergo a replacement reaction, and mercury is replaced and precipitated. "When bile water encounters iron, mercury will come out. Using iron as a medium to separate mercury from its salts. "This method is relatively simple, but the mercury obtained often contains impurities and needs to be further purified.
The above methods for synthesizing mercury are the crystallization of the wisdom of the ancients. Under the conditions of the time, they provided an effective way to obtain mercury and laid the foundation for the development of chemistry in later generations.

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First, mercury is volatile. In a confined space, its vapor is easily dispersed, and if inhaled, it will harm the viscera and damage the mind. Therefore, where mercury is used, it must be well ventilated to ensure that the vapor dissipates quickly and does not accumulate.
Second, mercury touches the skin and can penetrate into the skin, gradually accumulating. Therefore, when taking mercury, it must be stored in an appliance, and it should not be in direct contact with the skin. If it is accidentally contaminated, rinse it with water as soon as possible, and then seek good medical treatment.
Third, mercury utensils must be kept intact without leakage. If there is damage, mercury flows out and seeps into the ground, which is difficult to remove, evaporates for a long time, and is also very harmful. And to clean up the scattered mercury, you need to use specific things, such as sulfur powder, to make it harmless before it can be properly disposed of.
Fourth, after using mercury, store it properly. Keep it in a cool, dry place out of the reach of children to prevent accidental ingestion and cause major disasters.
Furthermore, those who use mercury should be familiar with its nature, understand its harm, and should not be negligent. A little carelessness can harm themselves or others. All matters involving mercury should be done with caution and follow the law to ensure safety.