2-pyridinecarboxaldehyde, 3-chloro-

The sharks in the sea are discussed in "Tiangong Kaiwu", and their main uses are as follows.
The sharks skin is tough and can be used as a scabbard for swords. The scabbard is decorated with the sharks skin, which is not only beautiful, but also wear-resistant to protect the blade, which can make the sword last for a long time. The ancient good blade is often matched with the scabbard of the sharks skin, which shows its preciousness and extraordinary. As in the past, when soldiers wore swords, the scabbard of the sharks skin could protect the body of the sword from damage during the march and add a bit of might.
The meat of the sharks, although it is not very beautiful, can also be eaten when there is a lack of food at sea. When sailing on the sea, if there is a shortage of grain and the mackerel is caught, its meat can temporarily relieve the pain of hunger, maintain life, and help the boat people get through difficult times.
In addition, the oil of the sharks burns brightly and lasts for a long time. In ancient times, when lighting was inconvenient, the oil of the sharks could be used as lamp oil. In the dark room, or when sailing at night on the sea, burning the oil lamp of the sharks can disperse the darkness, illuminate the road, and bring convenience to people's life and travel.
The bone of the sharks also has a wonderful use. It can be carved into various utensils, or small pieces for decoration, or practical utensils. Its texture is special, and it is unique after carving, which has both practical and ornamental value.
In short, the sharks in the sea have contributed to many aspects of ancient life. Although they are not rare treasures, they occupy a place in people's production and life with their unique functions.

Mercury, also known as mercury, is a liquid metal with a silvery flowing state at room temperature, which has unique physical properties.
The first to bear the brunt, the melting point of mercury is extremely low, about -38.87 ° C, which makes it capable of maintaining a liquid state in cold environments, unlike other things that solidify easily. Therefore, in the past, mercury was often the first choice for many liquid materials.
In addition, the boiling point of mercury is 356.6 ° C, which is relatively not very high, but it is also higher among common liquid substances. This allows mercury to remain stable in the liquid state for a long time in the normal temperature range, and rarely vaporizes rapidly due to slight changes in temperature.
The density of mercury is quite high, reaching 13.59g/cm ³, far exceeding the density of common liquids such as water. This high density makes mercury play a unique role in many experiments and technological applications. If placed on a liquid mercury, due to the high density of mercury, lighter objects can float on it, just like wood floats on water. This phenomenon has also been noticed by the ancients and has been applied in many experimental observations.
Mercury also has good electrical conductivity. Although it is slightly inferior to metals such as gold, silver, and copper, its electrical conductivity is also excellent in liquid substances. This property makes mercury play an important role in some specific electrical experiments and devices.
In addition, mercury is volatile to a certain extent, and under normal temperature and pressure, it will slowly evaporate mercury vapor. This property has both advantages and disadvantages. The advantage is that some reactions or processes that require the participation of mercury vapor can be realized; the disadvantage is that because of its toxic vapor, if accidentally inhaled, it will cause serious damage to human health.
In the long-term observation and practice, the ancients gradually understood and mastered the many physical properties of mercury. Although the understanding at that time was not as accurate as it is today, they were able to skillfully use its characteristics to exert the unique effects of mercury in the fields of alchemy, medicine, and process production.

Mercury, or mercury, is a unique metal. The element of mercury is liquid at room temperature and pressure, and it is silver and shiny. Its chemical properties have the following characteristics:
First, mercury can form amalgams with a variety of metals. "Tiangong Kaiwu" says: "Where silver is used in the world, but red copper and lead are base. Mercury is a great poison when it enters, and sulphur is invisible." This sentence mentions that mercury can interact with metals such as lead to form amalgams. The formation of amalgams is often due to the fact that mercury atoms can fill the lattice gaps of other metals, changing the properties of metals. For example, in the ancient gilding process, gold and mercury were first made into gold amalgam, which was applied to the surface of the utensils, and the mercury was volatilized by heating, while the gold was retained on the surface of the utensils for the purpose of decoration and protection.
Second, mercury can react with oxygen. Under heating conditions, mercury can combine with oxygen to form mercury oxide. Although this reaction is not detailed in "Tiangong Kaiwu", according to chemical principles, mercury is placed in the air, and if the temperature is suitable, it will gradually combine with oxygen. This reaction is also a redox reaction. Mercury loses electrons and is oxidized, and oxygen gains electrons are reduced.
Third, mercury can react with sulfur. The book says that "if you get sulfur, you will become invisible". This reaction is extremely rapid and violent. Mercury and sulfur powder are mixed and ground to form mercury sulfide in an instant. Mercury sulfide has high stability and is usually red in color. It was often used as a pigment in ancient times, called cinnabar. This property is extremely important in dealing with mercury leakage. Once mercury is sprinkled, sprinkling with sulfur powder can convert mercury into relatively harmless mercury sulfide to prevent mercury volatilization and cause poisoning.
Fourth, the chemical activity of mercury is relatively weak. Compared with common active metals, mercury is not easy to replace other metals in aqueous solution. If mercury is placed in a copper sulfate solution, it will not replace copper like iron. Because of its metal activity sequence, mercury is at the back of the metal activity sequence table and has weak electron loss ability, so it is not easy to replace with common metal salt solutions.

To make potassium cyanide, there are three methods.
One is the method of reacting hydrogen cyanide with potassium hydroxide. Take an appropriate amount of hydrogen cyanide gas and slowly pass it into the potassium hydroxide solution. The gas of hydrogen cyanide is strong and toxic. When operating, it must be in a well-ventilated place, and comprehensive protective equipment must be prepared to prevent the poison gas from hurting people. When the two meet, they will react to form potassium cyanide and water. The chemical formula is: HCN + KOH → KCN + H 2O O. After the reaction, the water will gradually disappear by evaporation to obtain the solid of potassium cyanide.
The second is the method of co-heating potassium carbonate with carbon and ammonia. Potassium carbonate, toner and ammonia are placed in a special high-temperature container in a suitable ratio. Then heat it with intense heat, and the temperature must be controlled within a specific range. Under this high temperature, potassium carbonate interacts with carbon and ammonia, and gradually generates potassium cyanide through a series of complex chemical changes. This process requires attention to the stability of temperature and the flow of gas. If the temperature is inappropriate or the gas is not smooth, the reaction can be blocked. The main reaction formula is roughly: K ² CO 🥰 + C + 2NH 🥰 → 2KCN + 3H ² O. After the reaction is completed, pure potassium cyanide can be obtained through various steps such as cooling, separation, and purification.
The third is the method of using cyanide-containing raw materials. If there are cyanide-containing ores or other cyanide-containing compounds, they can be pretreated to analyze or convert the cyanide content. Then, by means of chemical separation and reaction, they are combined with the potassium source to generate potassium cyanide. This process is quite complicated, including multi-step reaction and separation operations, and the conditions of each link need to be carefully controlled, and the selection and treatment of raw materials are crucial, which is related to the quality and quantity of the product.
However, it is necessary to remember that potassium cyanide is extremely toxic, and it involves great risk to make it and use it. Non-professionals and in compliance experimental sites must not do it. A little carelessness will cause toxic gas leakage, which will endanger life and harm the surrounding area.

For the use of the sea clam, its armor can be decorated, and its beads can be treasured. When it is used, pay attention to all things.
First, you need to choose the time to take the clam. The sea clam breeds beads, often according to the time of day and the change of the tide. The ebb and flow of the tide is related to the life and livelihood of the clam. Therefore, if you want to take the clam, you should observe the law of the tide. When the tide recedes, it is easy to find it when you go to the shallows and wetlands. If you act rashly, you will not notice the tide or the dangerous place, and endanger yourself.
Second, you should be careful when picking pearls. The sea clam hides pearls, and the pearls are in the clam, and it is not easy If the force is too strong, or the pearl quality is damaged, the value of the pearl will be reduced. And the pearl is born in the mussel and is connected to the mussel body. When stripping, it is necessary to use clever means to protect the integrity of the pearl.
Furthermore, protect the ecology of the mussel. The survival of sea mussels depends on the balance of marine ecology. If over-picking does not care about the reproduction of the mussels, it will lead to a sharp decrease in the number of mussels and a bad ecological order. Therefore, when picking mussels for pearls, there should be moderation and follow the rules of nature, so that the sea mussels will continue to grow and the resources will be inexhaustible.
In addition, with mussel armor as decoration, it should also be well carved. Although the mussel armor is beautiful, it is not carved, and When carving, it is necessary to follow the shape and color of the armor, and apply it with art, in order to achieve beautiful decoration. And the method of carving, when passed down with art, inherits the ingenuity of predecessors, and integrates new ideas into it.
When using sea clams, when taking clams, the method of pearling, ecological protection, carving art and other things, you should pay attention, so that you can make good use of sea clams, get the beauty of beading, and keep the ocean ecology.