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Mercury, lead, cadmium, etc. are all heavy metals, and their main uses are different.
Mercury was often used in alchemy in ancient times. The alchemists believed that through special refining methods, mercury and other substances could be turned into miraculous medicinal pills in pursuit of immortality. Although mercury alchemy was not described in detail in "Tiangong Kaiwu", it was mentioned in many ancient alchemy sutras. At the same time, mercury was also used in the production of mirrors because of its special physical properties. The ancients used mercury and tin mixed amalgam to apply to the back of the bronze mirror, which could enhance the reflective effect of the mirror.
Lead played a significant role in the field of ancient coinage. Lead was one of the important components in the coins minted by many dynasties. Due to the relatively soft texture of lead, it is easy to cast and form, and has certain wear resistance and corrosion resistance, which can keep coins relatively stable in circulation. In addition, lead is also indispensable in the production of type. When movable type printing was popular, the use of type greatly improved the efficiency and quality of book printing. Although the production of type is not emphasized in "Tiangong Kaiwu", the significance of lead characters in the process of cultural dissemination should not be underestimated.
Cadmium, although not as widely used as mercury and lead in ancient times, is also involved in some special metal smelting and alloy manufacturing. When the ancients explored the properties and combinations of metals, they accidentally discovered that cadmium could have a unique impact on the properties of certain alloys. Although the scope of application was limited, it was also part of the exploration of ancient metallurgical technology.
The different applications of these three heavy metals in ancient times reflected people's understanding and utilization of material properties at that time, and had unique value in promoting the development and progress of human society.

Mercury is unique in its nature. It is white and heavy in color. At room temperature, it is a liquid metal, which is unique among all metals. It has excellent fluidity, is agile to the touch, and rolls freely.
Water is also colorless and transparent, clear and pure, odorless and tasteless. Its nature is very soft, and it can be shaped at will. It has good solubility, and many substances can be dissolved into it. It also flows well, and it goes down with the flow without hindrance.
Tridna is hard in texture, which is transformed by the shell of shellfish in the sea. Its texture is unique, often with beautiful patterns, or like water waves, or like a nebula. Its color is warm and moist, or as white as frost and snow, or as transparent as condensation, and the luster is soft, which makes people love it. And because it is born in the sea, it has the essence of the ocean, as if it contains the mysterious atmosphere of the sea.
Mercury, water, and clam, the three have different physical properties, and each shows its unique style in the world, which is a wonderful product of natural creation.

If you want to make gunpowder, there are different methods.
First, you should use the method of fine grinding. First, take the clean saltpeter and grind it with a pestle and mortar to make the powder as fine as dust. Next, take the sulfur and grind it like the method, so that the powder of the two is uniform. As for the charcoal, it is better to choose the one with a firm texture. After burning, it is also ground into a fine powder. Then, according to the ratio of saltpeter seven, sulfur two, and charcoal one, put the three powders in one container, and stir them repeatedly with bamboo chopsticks or wooden spoons to achieve uniformity. This process needs to be very fine, and if it is slightly uneven, it will affect the effect of gunpowder.
Second, you can use the method of water melting. First place the saltpeter in the kettle, add an appropriate amount of water, and cook it over a slow fire. When the saltpeter is completely melted, it becomes a clear liquid. Then, take the fine powder of sulfur and charcoal, and slowly pour it into the saltpeter solution, while stirring it with a wooden stick. At this time, pay attention to the heat, do not make the fire too hot, causing the solution to overflow. When the three are fully mixed, remove the kettle from the fire, and wait for it to cool, the water will gradually dry, and the gunpowder will be ready.
Third, it is the method of dripping. Mix the saltpeter and sulfur in proportion, heat it to melt, and form a liquid. Then place the charcoal fine powder on a fine sieve, and slowly shake the sieve, so that the charcoal powder drips into the mixture of saltpeter and sulfur like a drizzle. At the same time, stir quickly with a shovel to mix quickly. After mixing evenly, pour it on a flat plate, let it cool and solidify, and then smash it into appropriate particles. Gunpowder is formed.
These several methods of combining gunpowder have their own advantages and disadvantages, and they need to be selected according to actual needs, material conditions and production conditions. The matter of combining gunpowder should be handled with caution, which is related to safety and should not be ignored.

Cast swords as soldiers, hide weapons in the body, just in case, this is a big deal. However, in the genus of iron, refined copper, and mithril, you need to pay attention to all things when casting swords and transporting them.

Iron is abnormally hard, extremely sharp, and brittle and easy to fold. When hiding, you need to choose a dry place to avoid water and wet air to prevent rust. Rust occurs, iron becomes soft, and the blade is dull and unusable. During transportation, wrap it in thick felt and line it with cork to prevent it from colliding. If the collision is too fierce, the sword body is prone to cracks. Although it has the essence of hundreds of refinements, it is difficult to recover.
The refined copper sword is tough in texture and spiritual. Hidden in a brocade box, the box is built with spices, such as agarwood, sandalwood, etc., to avoid filth and nourish its spirituality. When handling, handle it with care and do not make it bumpy. Although the refined copper is tough, it vibrates too much, and it also damages its quality.
As for the Mithril sword, it is a rare treasure, and it is very precious. There must be a hidden lock in the hiding place, and it is guarded day and night. Its weight is light, but it is cut iron like mud, and its edge is easy to leak. When hiding, you need to use a black iron box, and the box is covered with spiritual talismans to suppress its edge. When transporting, choose an old and serious person, and use a spell to bless it to protect its stability.
Furthermore, no matter what sword, the heart and blood of the swordsmith are condensed Those who hide swords should be in awe and should not desecrate them. When moving the sword, follow the ancient law and should not be hasty. Only in this way can the sword last for a long time, exert its due power, protect the master and defend himself, and make achievements.

On the banks of rivers and rivers, the land of mining and metallurgy is related to the livelihood of all people, and also involves many safety concerns. Today, in terms of mining and metallurgy, discuss its safety risks.
First, the risk of water and fire. Fire in mining and metallurgy, or due to dredging, causes fires to rise suddenly, flames soar, devour property, and endanger lives. And there is a lot of stagnant water in the mine. If the drainage system is not good, it will suddenly encounter floods, torrents rush, and roadways collapse, and people will be trapped in it, and they will be in danger.
Second, the harm of poisonous gas. Various things in the mine have been smelted or produced poisonous gas, such as sulfur compounds, lead and mercury vapors. If people inhale it, it will damage their internal organs, and they will be seriously ill for a long time. What's more, the accumulation of poisonous gas, in case of open fire or explosion, the power is amazing, the destruction will hurt people, and the disaster will not be great.
Third, the danger of roadway collapse. The mine is dug deep, and the rock layer is stressed. If the support method is improper, or in case of geological changes, the roof will fall, and the side wall will collapse. The operator will be buried in an instant, and life and death will be unpredictable.
Fourth, the risk of machinery. The equipment used in mining and metallurgy is huge, and when it is running, its strength will be huge. If the operation is wrong, or the equipment is out of repair, it will be the disaster of clipping, bumping, and twisting, which will easily injure limbs and cause lifelong disability.
Fifth, the disease of dust. Mine dust is flying, permeating the air, between people's breaths, dust enters the lungs. The sun accumulates and the moon gathers, the lung lobes are damaged, and eventually it becomes pneumoconiosis. Breathing is difficult and miserable.
The mining and metallurgy industry, although it is needed by the world, is surrounded by safety risks. Only by strict regulations, diligent prevention, and intensive research skills can we ensure the safety of everyone and make the industry prosperous.