Zinc, bis(2-pyridinecarboxylato-.kappa.N1,.kappa.O2)-, (T-4)-

The chemical structure of this substance has unique characteristics. Its structure is often highly regular, just like the pattern carefully arranged by the craftsmen of the heavenly palace. The atoms are connected in a specific bonding way, which is orderly, just like the stars in their respective positions in the sky. And the positions and bonding situations of each atom in the structure follow specific chemical rules, which are as strict as the laws of heaven.
Furthermore, its structure often shows a certain symmetry. Or left-right symmetry, or central symmetry, this symmetry gives the substance a unique beauty, just like the artifact of celestial carving, which is natural. This symmetry is not only related to the appearance, but also has a profound impact on its physical and chemical properties, just like the law of balance between heaven and earth, which affects many manifestations of the substance.
In addition, the chemical structure of the substance, the bonds formed by the atoms have different characteristics. Or it is a strong covalent bond that tightly connects the atoms, making its structure as solid as a rock; or it is a relatively weak force, but it is also indispensable in maintaining the stability of the overall structure, just like the various regulations in the celestial palace, which combine strength and weakness to jointly maintain the operation of the celestial court.
In addition, the spatial arrangement of atoms in the structure is also very particular. In three-dimensional space, atoms are distributed according to specific geometric shapes, forming a complex and delicate structure, like celestial palaces, with distinct layers and scattered patterns. This spatial configuration plays a decisive role in the interaction between the substance and other substances, such as chemical reactions, adsorption and other processes, just like the layout of the stars in the sky affects the operation of all things in the world.

A substance has applications in many fields. Viewed from the perspective of "Tiangong Kaiwu", it can be described as follows:
In the agricultural field, this substance may be a fertilizer. The book says: "If the soil has cold pulp, it is better to dip the ashes into the roots of the seedlings, and the lime floods the seedlings. It is not suitable to warm the soil to the sun." If this substance has fertilizer effects, it can nourish seedlings, improve the soil, and make grains flourish. For example, some substances rich in nitrogen, phosphorus and potassium can provide nutrients for crops and increase yield, just as farmyard manure and green manure are used in farmland to ensure the food needs of the people.
In the field of handicrafts, if this substance is metal ore, it is related to smelting and forging. " "Where mirrors are cast, grey sand is used for moulding, and tin and copper are used for moulding, it is also like casting money." Metal ores are smelted to obtain metals, which are used to cast all kinds of utensils, such as agricultural tools, weapons, and living utensils. Farming tools make farming more efficient, weapons ensure the safety of the family and the country, and living utensils facilitate the daily life of the people and promote the development of handicrafts.
In terms of construction, if it is clay or the like, bricks and tiles can be made. "Where clay is used to make tiles, dig more than two feet into the ground, and choose soil without sand sticking (through'sticky ')." Clay is shaped and fired into solid bricks and tiles, which are used to build houses, shelter people from wind and rain, and build a stable place to live.
In the pottery industry, suitable clay or other raw materials can be made into exquisite pottery through ingenious craftsmanship. "A total of one billet of labor, seventy-two in hand, and a square gram becomes a tool." Pottery is used for storage, diet, etc., enriching people's lives.
Although the chemical field is not as modern as the system, some substances also react with each other. For example, in the process of alchemy, various ores and drugs are mixed. If this substance participates in such reactions, it may generate new substances and bring different effects. Although it is different from modern chemistry, it also accumulates experience for the development of chemistry. In short, according to its characteristics, this substance has important applications in agriculture, handicrafts, construction, pottery and other fields, and has a profound impact on people's lives and social development.

The physical properties of a substance are related to its shape, color, odor, density, melting point, boiling point, hardness, solubility, and many other aspects. The following will be described in detail in ancient Chinese sayings.
Looking at the shape of a substance, there are differences between gaseous, liquid, and solid states. Gaseous states are light and formless, pervading the four directions, like clouds and fog, elusive. Liquid states are fluid and can change with the shape of the vessel, such as the softness of water, without amorphous shape. Solid states are fixed in shape, solid in quality, and not easy to deform.
Color is also an important characteristic of matter. Or red like sand, bright and dazzling; or green like jade, warm and elegant; or white like frost and snow, pure and flawless. The brilliance of its color is due to the difference in the internal structure and composition of the substance.
As for the smell, there are those who are fragrant and rich, such as the fragrance of the orchid, which is refreshing; there are also those who smell bad, such as the smell of rot, which is noxious. The uniqueness of this smell is caused by the molecular properties of the substance.
The density is related to the mass of the unit volume of the substance. The heavy one sinks, and the light one is floating. If the genus of gold and iron has a high density, it will sink when placed in water; while the wood and bamboo have a low density and can float on the water surface.
The melting point and boiling point are the key temperatures for the transformation of the state of matter. The melting point is the temperature at which the solid state melts into a liquid state. When the temperature rises to the melting point, the substance changes from solid to liquid and gradually changes its shape. The boiling point is the temperature at which the liquid boils to gaseous state. At this temperature, the liquid tumbles and water vapor evaporates.
Hardness reflects the ability of the substance to resist deformation. Goldstone is hard and can be engraved; while plaster is soft and easy to shape.
Solubility is related to the ability of the substance to dissolve in solvents. Or easily soluble in water, such as salt sugar; or poorly soluble in water, such as the genus of grease. This is due to the interaction between the substance and the solvent molecules.
The physical properties of matter are so complex and diverse, each with its own differences. Only by observing and distinguishing them can we know the characteristics of matter, which is of great significance in daily use, technology, and academia.

Many of the things recorded in "Tiangong Kaiwu" have detailed records of craftsmanship. However, because no specific things are mentioned, the following is only to take the common thing "paper" as an example to describe its ancient production method.
In the production of paper, the first thing to do is to prepare materials. Choose suitable fiber raw materials such as chu peel and bamboo. If you use chu peel as material, take the chu tree first, peel the skin, and soak it in lime water. The lime water has the effect of corrosion and softening, which can make the chu peel fibers easier to separate. After a few days of soaking, remove and cook. When cooking, the fire needs to be uniform and long-lasting, so that the chu peel fibers are completely soft and rotten.
After cooking, take out the material and put it in a stone mortar. The purpose of pounding is to further refine the fibers to make a uniform pulp. The pounding process requires force and meticulousness, so that the fibers are all broken and uniform.
When the pulp is ready, it is papermaking. Gently scoop the bamboo curtain into the pulp, so that a thin layer of pulp is evenly attached to the bamboo curtain, and the excess water is drained from the four sides of the bamboo curtain. This step requires skilled techniques to make the paper have the same thickness.
After copying the paper, press the paper. Place the bamboo curtain attached to the pulp on a wooden board, then cover it with another wooden board, and press it with a heavy object. With the pressure of the heavy object, squeeze out the remaining water in the paper to make the paper initially formed and compacted.
After pressing the paper, the paper is baked. Remove the initial forming paper and stick it in the "alley" to dry. The "alley" is made of earth bricks with a fire channel. The paper is attached to the wall and dried slowly. Pay attention to the heat and ventilation, and do not overheat too quickly to avoid paper cracking. After these several processes, a piece of paper is completed.

The stability of a substance is related to its ability to resist external influences and maintain its own characteristics. Looking at "Tiangong Kaiwu", although it does not directly discuss all substances with "stability", the records of the properties and changes of various substances in the book can reflect the principles related to their stability.
For metal substances, such as "where gold is the length of hardware, after melting and forming, it will never change in the world", this sentence states that gold is extremely stable. After melting and forming, under normal circumstances, it is extremely difficult to react with external factors and can maintain its own shape and properties for a long time, so it is "never change in the world". This is because the chemical properties of gold are extremely stable and are not easily affected by oxidation, corrosion and other effects. < Br >
Look at the firing of various ceramics again. "Water and fire are both good and earth is combined. Where the billet is ready, after drying, it is fired in the kiln." Clay is made into a billet, and after drying, it is fired at high temperature into ceramics. Once the ceramic is fired, its stability is quite impressive. It can withstand a certain degree of temperature change and chemical attack. This is because during the firing process, the composition of the clay is chemically reacted to form a new structure, so that it has good stability. Like the ceramic utensils used in daily use, it can be used to hold all kinds of food and liquids for a long time without significant change in its own properties.
However, there are also some materials that are slightly less stable. Such as some pigments mentioned in the book. Pigments gradually lose their color during the drawing process and preservation, or due to factors such as light and air humidity. This indicates that such pigments are not stable enough and are easily affected by the external environment.
Overall, the stability of substances varies. Those with high stability, such as gold and ceramics, can maintain their own characteristics for a long time in a variety of environments; those with low stability, such as some pigments, are easily changed by external actions. This is all related to the composition, structure and external environment of the substance itself.