Pyrazine, 2-chloro-

According to the records in "Tiangong Kaiwu", the main use of the husk is to break the grain and extract the rice. The husk is a rice-pounding device and comes in a variety of shapes. It is constructed of bamboo and wood, and it is equipped with hard grinding teeth. Driven by human or animal power, the rice is rubbed against each other in the husk, thereby stripping the husk from the rice grain. This process is like a delicate dance of natural and human cooperation. The husks fall off one after another, and the rice grains take shape.
The husk played a key role in the processing of ancient grains. After the grain is harvested, the first step is to remove the husk through the action of the husk, so that the subsequent pounding process can be further processed. This tool greatly improves the efficiency of rice extraction, and has a significant improvement in both speed and labor intensity compared with the previous manual shelling method.
Among the people, the dragon is indispensable for every household to handle rice. Whether it is in the southern water towns or the northern plains, as long as there is a place where rice is grown, the dragon can be seen. Its operating principle is simple and practical, and it skillfully uses friction to complete the initial separation of grain and rice, providing a crucial boost for human beings to obtain staple food. In the long years of farming, it silently promotes the development of grain processing skills.

Mercury is a highly toxic liquid metal with different physical properties. Under normal temperature and pressure, mercury is in a liquid state, like flowing silver, shining brightly and dazzling. Its melting point is extremely low, only -38.87 ° C, so it can maintain a liquid state at room temperature; while the boiling point is 356.6 ° C.
Mercury has a high density, about thirteen times that of water, reaching 13.59 g/cm ³. This property allows mercury to sink to the bottom immediately when placed in water. Its fluidity is very good, and it is easy to disperse into many tiny droplets, and when these droplets collide with each other, they are very easy to fuse into one.
Mercury has excellent electrical conductivity and is occasionally used in circuits and electrical devices. At the same time, mercury also has good thermal conductivity and can quickly transfer heat.
In addition, mercury and most metals can form amalgams, which is one of the major characteristics of mercury. Many metals such as gold, silver, zinc, etc., can form amalgams with mercury, and the process of forming amalgams is relatively simple.
However, it is important to pay special attention that mercury and its compounds are highly toxic. Once inhaled by the human body, mercury vapor can cause serious damage to the nervous system, kidneys and many other organs. When using and disposing of mercury, it is necessary to follow strict safety procedures to prevent mercury leakage from causing harm.

Mercury is very different in nature. Its quality is a liquid in normal state, like silver, so it is also called mercury.
Mercury has various chemical properties. First, it is quite active. Although it is slightly inferior to potassium, sodium, etc., it can also react with many substances. In case of sulfur, the two quickly combine to produce mercury sulfide, which is the main component of cinnabar. The ancients used mercury and sulfur to co-refine in the matter of Dan Dao. Observe its changes and know the wonders of this combination.
Second, mercury oxides are diverse. When heated, mercury can combine with oxygen to form mercury oxide. Mercury oxide can be decomposed when heated, and it can also be recycled into mercury and oxygen. This process seems to have a way of circulation, just like the reciprocal changes between heaven and earth.
Third, mercury behaves differently in acids. When encountering nitric acid, it can react with it, generating mercury nitrate, and gas escapes. Looking at it, it looks like bubbles are churning. When encountering sulfuric acid and hydrochloric acid, if there are no special conditions, it is difficult to react. It seems to have its own nature and should be rejected.
Fourth, mercury is toxic, and this property is also related to its chemical properties. Its ions can combine with proteins, enzymes, etc. in living organisms, disrupting its normal physiological functions. Although the ancients did not have to fully understand its microscopic principles, they also knew the harm of mercury toxicity in practice, so they were cautious when using it.
The chemical properties of mercury are unique and diverse. In various chemical reactions, they can be combined, decomposed, or interacted with other things. They all reveal the wonders of creation in heaven and earth, and also enable the ancients to gain many enlightenments in exploring the way of material change.

The synthesis method of mercury to arsenic is quite complicated and needs to be done with caution. The ancients explored this in alchemy and other alchemy techniques, but the methods at that time, based on the present, may be fallacious and dangerous. The following are some common synthesis ideas you describe in detail. Although it may not be entirely feasible today, you can also see the trajectory of the ancients' exploration.
One of them starts with minerals containing mercury and arsenic. For example, Dan sand is an important mineral of mercury, and realgar is a common mineral of arsenic. The ancients may have first sublimated Dan sand by heating it to obtain the elemental substance of mercury. "Puzi · Nei Pian" has a saying: "Dan sand burns into mercury, and the accumulation changes into Dan sand." That is to say, Dan sand is decomposed into mercury by heat. Then, realgar is also heat-treated, and realgar is heated to produce arsenic and other arsenic-containing compounds. Then try to make mercury and arsenic-containing compounds react under specific conditions. Or in a closed cauldron, heat it slowly with charcoal fire, hoping that the two will have a chemical reaction. However, this process is extremely difficult to precisely control, and arsenic and other arsenic-containing compounds are highly toxic. If you are not careful, it is easy to cause poisoning.
Second, try to use pharmaceuticals to assist in synthesis. The ancients often used various kinds of herbal juices as a medium. Or take some plants with special properties and mix them with mercury and arsenic-containing minerals after juicing. For example, some plant juices may contain special organic ingredients, which can react with mercury and arsenic ions to change their chemical activity and promote the combination of the two. However, the understanding of the principle of chemical reactions was limited at that time, and it was mostly tried based on experience, so the success rate was not high, and the chemicals used may have complex side reactions with mercury and arsenic, making it difficult to obtain pure mercury-arsenic compounds.
Third, simulate the natural environment. Observe the phenomenon of symbiosis of certain minerals in nature, and speculate that mercury and arsenic may be synthesized naturally under specific geological conditions. Therefore, simulate such an environment, such as creating an environment with high temperature, high pressure and a specific pH. In the cave, a special container is set up to simulate the environment deep underground, maintain the temperature with charcoal fire, and adjust the pH with water and some alkaline and acidic substances. However, such simulations are difficult to completely restore the complex conditions of nature, and the synthesis effect is not good. In short, the ancients in the synthesis of mercury to arsenic, although unremitting exploration, but limited to cognition and technology, failed to perfect the method.

Mercury is a highly toxic substance, and when using mercury, many matters need to be paid attention to.
First, it is related to protection. When taking mercury, you must wear protective clothing, a protective hat, protective gloves, and a gas mask to prevent mercury vapor from invading the human body and poisoning the internal organs. The operation area also needs to be well ventilated, and it is best to have ventilation equipment to promote mercury vapor to dissipate as soon as possible without accumulating.
Second, about the preservation of mercury. Mercury should be stored in a sealed container to prevent it from evaporating in the air. And the container should be placed in a cool, dry place, away from heat and fire sources, so as not to exacerbate mercury volatilization due to rising temperature. If mercury is accidentally spilled, be sure to deal with it immediately. First use a mercury absorber to collect the spilled mercury as much as possible, and then sprinkle sulfur powder on the residual mercury to make mercury and sulfur form mercury sulfide, which is a stable compound that can reduce the toxicity and volatility of mercury.
Third, the operation process is also exquisite. When using mercury for experiments or other operations, the action must be gentle to avoid mercury splashing. The utensils used must be dry and clean to prevent impurities from affecting the properties of mercury, and to avoid chemical reactions to produce harmful substances. In addition, do not eat, drink, smoke during the operation to prevent mercury from entering the body through the mouth.
Fourth, the disposal of waste mercury must not be discarded at will. Waste mercury needs to be collected in a specific container and handed over to a professional organization for treatment to avoid pollution to the environment, endangering ecological balance and the health of all living beings.
In short, when using mercury, protection, preservation, operation and disposal must be strictly followed, and must not be taken lightly, so as to ensure personal safety and the environment from mercury damage.