Pyrazine, 2-bromo-5-iodo-

Mercury, commonly known as mercury, is a highly toxic chemical substance. It is unique in nature. Under normal temperature and pressure, it is liquid and easy to flow, like a silver-white fluid, shining with metallic luster.
Mercury's chemical properties are relatively stable, and it is not easy to react with oxygen, but it can chemically change with many substances such as sulfur. At high temperatures, mercury can combine with oxygen to form mercury oxide. And mercury is volatile, and it will slowly evaporate into mercury vapor at room temperature. This mercury vapor is particularly toxic. If inhaled by the human body, it will cause serious damage to the nervous system, kidneys and many other organs.
Looking at "Tiangong Kaiyi", its characteristics of mercury are also recorded. Mercury mostly exists in the form of mercury sulfide in nature, such as cinnabar, which is a common mercury-containing mineral. After the ancients mined cinnabar, mercury was extracted through a series of processes. The ancients also knew the toxicity of mercury. Because of its significant toxicity, special caution is required when using it. Although mercury is toxic, it also had its uses in ancient times. For example, in alchemy, mercury is often regarded as an important thing. Warlocks tried to use mercury and other substances to refine longevity pills. Although this is absurd, it reflects the degree of attention mercury received at that time. In some anti-corrosion fields, mercury has also been used because its toxicity can inhibit the growth of microorganisms and prolong the preservation time of objects. However, with the deepening of awareness, people have become increasingly aware of the toxic hazards of mercury, and more attention has been paid to its use and protection to prevent mercury from causing serious damage to the human body and the environment.

"Tiangong Kaiwu" says: "All the materials used in the billet are divided into stone soil. The soil should be uncultivated soil, and the stone should be taken from the mountain." The earth and stone of the billet have their own characteristics.
The stone of the billet is dense in texture, hard and difficult to cut, but it has strong fire resistance. If it is used to make the billet of the kiln, it can withstand high temperature without melting. Its properties are stable, not easy to deform, and can ensure the regularity of the utensils. For those with heavy stone properties, the sound of knocking is crisp, like the sound of gold and stone.
As for the soil of the billet, it is delicate and smooth, has good plasticity, and is easy to knead and shape. However, its hardness is inferior to that of the stone, if the heat is not appropriate, it is easy to cause deformation. If the soil is delicate, it feels warm and moist to the touch, and the surface luster is soft after firing, which is quite charming.
The soil and stone nature of the blank has a great impact on the quality of the utensils. The stone nature makes the utensils sturdy and durable, and can withstand years without damage; the soil quality gives the utensils a flexible state, showing the ingenuity of craftsmen. The two complement each other, and it is difficult to make beautiful utensils without one. If you want to make a solid utensil, it should be heavy stone; if you want a delicate shape, you should choose the soil quality.
In the stone soil quality of the blank, the ancients have long had insight and made good use of it, so that many exquisite utensils have been handed down and admired by later generations.

In "Tiangong Kaiwu", the canopy is an important part of the ship's equipment, and its main use is quite extensive.
The main purpose of the canopy is to protect the wind and rain. Vessels sail on rivers, lakes and seas, and the weather is unpredictable, and wind and rain often come unexpectedly. With its solid construction and suitable coverage, the canopy is like a huge umbrella company, which protects the crew and the cargo on board from wind and rain. In the event of strong winds and rain, the crew can safely control the ship under the shelter of the canopy to ensure the safety of navigation; the cargo can also be protected from rain and avoid damage.
Secondly, the canopy can be shaded from the sun and heat. When the hot sun hangs high, strong sunlight exposure will cause the temperature in the cabin to rise sharply, which not only makes the crew unbearably hot, affects work efficiency and physical health, but also may have adverse effects on some temperature-sensitive cargo. The cabin canopy can effectively block direct sunlight, reduce the temperature in the cabin, create a relatively comfortable environment, and protect the crew's work and cargo storage conditions.
Furthermore, the cabin canopy has a certain concealment effect. In water activities, people sometimes need a certain degree of privacy. Whether it is crew rest or transporting some goods that need to be kept confidential, the cabin canopy can block the outside world's line of sight, providing a relatively independent space and avoiding peeping by others.
In addition, some cabins are exquisitely designed and can also assist ships in sailing. For example, under specific wind direction and wind conditions, a reasonable adjustment of the canopy angle can be like a simple sail, leveraging the wind to provide a certain amount of assistance for the ship to move forward, saving manpower while improving sailing speed and efficiency.

"Tiangong Kaiwu" contains that the method of casting bells is related to many shapes, materials and craftsmanship.
The shape of a bell, whether round or flat, with a round bell sound and a flat bell sound, is suitable for each. Its size also needs to be considered, the big one is loud, and the small one is clear, all according to the needs of the user.
As for the material, most of them are copper, supplemented by tin and lead. Copper is tough, tin can be tuned, and lead can help melt. The ratio of copper to tin is related to the quality of the bell. The size of the bell is different, and the ratio of copper to tin is also different. The system of a large bell has more copper and less tin; the small bell has slightly more copper and tin.
The process of casting a bell is very important. First make the clay mold, carefully engraved, the texture pattern is meticulous, this is the embryonic form of the bell. Then make the outer model, wrap the clay mold with sand mud and other materials, layer by layer, to ensure that its shape is stable. Then melt the copper, burn it with charcoal fire, and melt the copper, tin and lead alloy. The temperature is controlled by the experience of the craftsman. Wait for the copper liquid to surge like golden waves, pour it into the mold, flow slowly, and fill it up everywhere.
After casting, wait for it to cool, and carefully remove the outer model of the mud mold, the rough blank of this clock has been completed. However, it has not been completed yet, and it needs to be carefully polished to make the bell body smooth and correct defects. Finally, inscriptions are engraved on the bell, or the reason for the bell, or the words of prayer, to add cultural heritage to the bell.
All these are the methods of casting bells, condensing the wisdom of ancient craftsmen, making the bell sound melodious and passed on to future generations.

Casting swords is a tool, which is related to the inheritance of skills, as well as safety and quality. In the process of storage and transportation, it is especially necessary to be cautious.
First, when storing, think about the material characteristics. Iron, copper, etc. used in casting swords are easily corroded by moisture and rust, damaging their texture. Therefore, it is necessary to choose a dry and ventilated place to avoid dark and humid places. If hidden in a secret room, a desiccant such as lime can be placed to keep the environment dry. And the swordsmanship is sharp. If it is stacked at will, it may cause damage to the cutting edge. It should be placed separately. Each has its own position, which not only protects the sword body, but also can be used.
Second, when transporting, safety comes first. The sword is a sharp weapon, and if you don't pay attention, it will cause a disaster. It must be wrapped in a thick cloth or a special sheath to hide its edge and prevent bumps on the way. When loading the car, it should also be placed firmly, and it should not be shaken and collided. If it is transported for a long time, the road conditions should be taken into account. If it is rough, it is necessary to move slowly and steadily to avoid damage. And the person who transports it should know the value and danger of the sword, abide by the rules, and do not slack off.
Furthermore, no matter whether it is stored or transported, there must be a special person responsible. This person should know the art of forging swords, know the value of the sword, regularly check the condition of the sword, and if there is any abnormality, dispose of it in time. When storing, check whether it is rusted or not, and check whether it is stable during transportation to ensure that the sword is intact. From the place where the sword is forged to the place where the sword is used, In this way, the sword can be safely stored, transported smoothly, passed on its spirit, and its skills can be promoted.