5-Chloropyridine-2-carboxaldehyde

It is recorded in "Tiangong Kaiwu" that sheep casings are mainly used to make bow strings.
Those who have sheep intestines are tough and elastic, and should be the strings of the bow. The hair of the bow covers the arrow, and the elastic force of the string is used to shoot the arrow. Those who have the string of the sheep intestines can store energy and quickly send the arrow, so that the arrow can travel far and powerful. The method of its production is to choose the tough one of the sheep intestines, and after various treatments, remove the filth, make it even, and then stretch it on the bow.
In ancient times, in combat and hunting, the bow was an important equipment. The performance of the sheep intestine string has a great impact on the bow. Compared with other objects as strings, it can better meet the shape and force requirements of the bow. When the bow is full of strings, the intestinal string of the sheep is deformed by force, converting manpower into elastic potential energy, and when the string is released by the hand, the potential energy is suddenly converted into kinetic energy, which drives the arrow to shoot out quickly.
And in archery competitions, military drills and other occasions, the bow of the intestinal string of the sheep is also common. It helps the shooter to accurately hit the target, and plays an indispensable role in the battlefield and daily shooting and hunting activities in the era of cold weapons. Therefore, the use of the intestinal string of the sheep is a manifestation of the wisdom of the ancients, which is of great significance to the military and production at that time.

The synthesis of mercury in ancient times was studied by many alchemists, and the methods were different. I will briefly describe it today.
First, use Dan sand to burn into mercury. In the case of Dan sand, mercury sulfide is also calcined and decomposed, and mercury comes out of it. "Baopuzi Inner Chapter" says: "Dan sand burns into mercury, and the accumulation changes into Dan sand." This is the ancient people's wonderful observation of the transformation of mercury and Dan sand. First take an appropriate amount of Dan sand, put it in a closed cauldron, and slowly burn it with charcoal fire. When it changes, mercury will precipitate out of the wall.
Second, use lead amalgam method. Lead and mercury can be fused to form lead amalgam. Put lead in a container, heat and melt, and add mercury, and mix the two. After that, the mercury is separated from the lead amalgam by an appropriate method, such as distillation.
Third, it is made of aluminium stone and other mercury-related substances. There are many kinds of aluminium stone, and some aluminium stone and mercury or its compounds can also obtain mercury after specific treatment. The method may require multiple processes, such as grinding, mixing, and roasting. First, the aluminium stone is ground into a fine powder, mixed in proportion with the mercury-containing substance, and placed in a stove to be roasted at a suitable temperature. During the process, its changes are closely observed. After many refinements, pure mercury can be obtained.
Fourth, the synthesis is assisted by herbs. Ancient alchemists believed that certain herbs were combined with mercury and its related minerals, or could promote the synthesis of mercury. However, there are many mysteries in this, and many of them contain speculative ingredients. Select a specific herb, wash it and dry it in the sun, place it in a stone mortar with mercury ore, pounded into mud, then placed in a clay pot, sealed, buried in the soil for a few days, and then taken out for treatment. However, the effect of this method is often unstable, and the effect is elusive due to the complex composition of herbs.
All these methods are attempts by the ancients to explore mercury synthesis. Although many of them are unscientific, they also reflect the unremitting exploration of material changes at that time.

Zinc and mercury, with various physical properties. Zinc is blue-white in color and slightly brittle in texture, but it can be easily formed by melting and casting. Its melting degree is quite low, about 419.53 degrees Celsius, and its boiling point is 907.0 degrees Celsius. At ordinary temperatures, zinc can be kept solid, but when heated, it gradually melts into a liquid. Its density is about 7.14 grams per cubic centimeter, which is heavier than water, and sinks when placed in water.
Zinc is chemically active and easily reacts with various substances. When it encounters acids, such as sulfuric acid and hydrochloric acid, it will react violently and release hydrogen gas. In the air, zinc can be gradually oxidized, and a layer of zinc oxide film is formed on its surface. Although this film is thin, it can protect the zinc under it and slow down its further oxidation, so zinc is often used to prevent rust.
Mercury is the only metal that is liquid at room temperature, commonly known as mercury. Its color is silver-white, shiny and fluidity is good. Mercury has a great density, reaching 13.59 grams per cubic centimeter, so it can support various objects, such as gold and silver. Gold belongs to mercury and can float on its surface.
Mercury has an extremely low melting degree, which is minus 38.87 degrees Celsius, and its boiling point is 356.6 degrees Celsius. Its vapor pressure is also higher at room temperature, so if mercury is accidentally spilled, it is easy to volatilize in the air. Although mercury is chemically stable, it can also form amalgam with some metals. If it meets sodium, it can form sodium amalgam. And mercury can combine with sulfide to form mercury sulfide, which is often used to remove mercury pollution.

Potassium and mercury are chemical substances. Its properties are strange and there are many wonders, let me tell you one by one.
Among potassium and mercury, potassium is very active. Potassium alone ignites violently in contact with water, and its shape is like a dragon's fire leaping, hissing, and immediately converts into potassium hydroxide and hydrogen. This is because its electronegativity is very small, it is very easy to lose electrons, and it is often highly reducible in chemical reactions.
As for mercury, it is a liquid metal at room temperature, and silver optical flows like a spiritual liquid. The boiling point of mercury is quite high, but the vapor pressure is very low. Its chemical properties are relatively stable, and it is not easy to react with many substances. However, when it encounters strong oxidants, it can also be synthesized into new substances.
When potassium and mercury are combined into potassium amalgam, it has both properties. Potassium in potassium amalgam has a slightly convergent activity, but it is still highly reductive. It has a wide range of uses in organic synthesis and can be used as a reducing agent to promote specific reactions. And potassium amalgam is also used in the battery field, because of its unique electrochemical properties, it may optimize the performance of batteries.
The properties of potassium and mercury are both active and stable. The blending of the two shows its ability in many fields such as chemical industry and scientific research. It helps humans to explore the material world and develop science and technology.

In today's market, the price of turtles varies from place to time. I have heard that the price of turtles is as low as tens of dollars per catty, and as high as hundreds of dollars per catty.
The price varies from one reason to another. First, it depends on the type of turtle. The turtle is a wild turtle or an artificial one. Wild turtles grow in nature and eat natural bait. Their quality and taste are good, so the price is often high. Artificial turtles grow faster, but their taste may not be as good as wild ones, and the price is slightly lower.
Second, it is related to the size of the turtle. Large turtles have thick and fat meat, and the price is higher if the eater likes it. The smaller ones are slightly inferior, and the price is correspondingly lower.
Third, the supply and demand of the city also has a great impact on the price. If the season is in season, and everyone wants to buy turtles for food, they need more and less, and the price will rise. If in normal times, the supply exceeds the demand, the price will drop.
Also, the distance of the land is also a factor. In the place where the turtle is produced, the supply is more and the price is flat. To remote places, the price will increase through transshipment.
Generally speaking, the price of turtle in the market is about tens of dollars to hundreds of dollars per catty, but this is only a rough estimate. In fact, it varies depending on time, place, category, size, and supply and demand.