pyridine and urea

Where is the main user of the Tao to his son?
The person who wants to be the one who wants to guide him is also the one who leads him. In ancient times, if you want to understand human feelings and reason about things, you must use your words. If you are walking in a maze, you will not know where you are going; if you are involved in the road, you will be led to follow the way. Therefore, the use of the direction is in the mind of the person, leading him to act and stop, so that he can avoid benefits and harm, and follow the right path. Like the disciple of the person, using words to refer to his work, and using reason to understand his method of standing, the key to this direction is also.
As for the child of the child, it is the thing to measure, and take the meaning of its discernment. The things of the heavens and the earth are multiplied and multiplied, if the child is to analyze them, there is no distinction between the good and the beautiful, and the beauty is indistinguishable. Therefore, the use of the child is to observe the fine and the right, to distinguish right from the wrong. A gentleman is in the world, with the heart of a son, to observe the goodness of things, and the loyalty and disloyalty of people. In this way, the study of reason should not make the slightest difference; in political affairs, it is necessary to discern the pros and cons, so as not to make mistakes. Only in this way can we act appropriately and take measures appropriately.
To those who want to, lead them to do; to those who want to, and to those who want to do it; to those who want to, to those who want to do it, to correct them. The two are related to each other, and they are essential to life. If you want to go to the direction, Only when you are clear to your child can you stand in the world and achieve your deeds, without being entrusted by this life.

Fuyang flintlock and sulfur, both of which have specific physical properties.
The sun flintlock is an ancient fire-making tool, made of copper-tin alloy, in the shape of a concave mirror. Its property is also that it can gather sunlight and make fire. Because the surface of the sun flintlock is smooth and concave, the sun is projected on it, and it is reflected and focused on a point. Where this focus is focused, light energy converges, and the temperature rises sharply, so that flammable things can catch fire. "Huainan Wanbi Shu" says: "Cut ice to make a circle, raise it to the sun, and use Ai to carry its shadow, and then fire will be born." Although it is said that cutting ice to make fire, the reason why the sun flintlock makes fire is the same, all of which use optical principles to gather light to generate heat.
As for sulphur, it is a yellow crystal and is flammable. Sulphur burns, the flame is light blue, and accompanied by a pungent smell. Its ignition point is low, and it is easy to catch fire when heated in the air. In ancient times, sulphur was often used in many fields. For example, in alchemy, sulphur was an important raw material. Warlocks believed that it had a magical effect and could be used to refine longevity pills. And because of its flammability, it is also used in military applications, such as making gunpowder. Gunpowder is mixed with sulphur, saltpeter, and charcoal in a certain proportion. After igniting, it can burn quickly, generating huge energy and triggering explosions. It is very powerful in war.
Yang flintlock can make fire due to its physical properties of optical focusing, while sulfur plays an important role in alchemy and military due to its flammable properties. Although the two have different physical properties, they both have unique significance and uses in the life and practice of the ancients.

Zinc and boron are widely used in chemical reactions.
Let's talk about zinc first. In the metallurgical field, it is often used for galvanizing. This is by plating zinc on the surface of iron or steel to build a dense protective film, which can effectively resist the erosion of metals by air, water, etc., and greatly improve the corrosion resistance of metals. As Kao Gong Ji puts it: "There are six levels of gold, six points of gold and tin in one, which is called the unity of the bell and tripod; five points of gold and tin in one, which is called the unity of the axe and catty; four points of gold and tin in one, which is called the unity of the halberd; three points of gold and tin in one, which is called the unity of the big blade; five points of gold and tin in two, which is called the unity of the killing arrow; gold and tin in half, which is called the unity of the flintlock." Although zinc was not mentioned at that time, it shows the ancient people's research on the application of metal proportions. Zinc is plated on the surface of the metal, which is like a armor for it, so that it can survive in harsh environments.
In the chemical industry, zinc is also a catalyst for many chemical reactions. For example, in organic synthesis reactions, some reactions require hydrogenation or dehydrogenation. Zinc and its compounds can speed up the reaction rate and reduce the activation energy required for the reaction, just like paving a smoother path for the reaction, making the reaction efficient.
Besides boron, in the glass manufacturing industry, borax is an indispensable raw material. Adding borax can significantly improve the thermal and chemical stability of glass. It makes glass products less prone to cracking when the temperature changes abruptly, and more resistant to acid and alkali corrosion. Although the ancients did not have such a deep understanding of the chemical principle of boron as they do today, in long-term practice, they must have noticed that the performance of glass improved after some substances were added to glass raw materials. Boron is like a good friend of glass, giving it more excellent quality.
In the field of agriculture, boron is an essential trace element for plant growth. Appropriate amount of boron can promote plant pollen germination and pollen tube elongation, which is conducive to plant pollination and fertilization, and improves fruit setting rate. When boron is deficient, plants are prone to poor growth and unfruiting flowers. This is like a guide for crop growth, helping them to multiply and grow normally.
To sum up, zinc and boron play a key role in industry, agriculture and other aspects, and have a profound impact on human production and life.

There is a question today, what is the production method of glauberite and turmeric sand? Try to imitate "Tiangong Kaiwu" and ask this question in ancient texts.
Glauberite, its production is also mostly from salt lakes and salt springs. On the other side, the brine is exposed to the sun, the water is gradually evaporated, and the salts are precipitated. Among them, glauberite is easy to crystallize when the temperature becomes cold. The method of mining is to take brine and fry it first, wait for it to be slightly thicker, and place it in an open place. When it is cold, glauberite will form on the four walls and bottom of the utensil, and scrape it to get the crude product of glauberite. Later, it is dissolved in water, filtered out its impurities, and then evaporated and crystallized to obtain pure glauberite.
The sand is often born in volcanic rocks and The method of its production is quite laborious. Before the ore veins, ore containing kao sand is mined. The ore is crushed and leached with water. The kao sand dissolves in water, while the remaining stone is insoluble. The leaching liquid is precipitated and filtered to remove its dross. After that, the clear liquid is put into the kettle and fried over fire. The size of the fire needs to be properly pinched. If the fire is large, the kao sand is vulnerable, and if the fire is small, it evaporates too slowly. When the water is less and less, the kao sand gradually gathers, and it is dipped in bamboo strips and the like, depending on the silk, that is, stop the fire. When it cools, the kao sand crystallizes. However, the sand is very dry, and when refining, it needs to be carefully protected to avoid hurting the body.
In summary, mirabilite is produced by brine and crystallized by cold; cauldron sand comes from ore and is leached and fried. The production methods of the two have their own needs, and they all depend on manpower and time to cooperate.

The effects of lead and selenium on the environment and human health have been observed in ancient times. Lead is heavy and toxic. In the environment, lead is easy to accumulate. Either in water and soil, or floating in the air. If lead enters the water body, all aquatic things are affected by it, and the growth and reproduction of fish and turtles are blocked. If it enters the soil, the life of vegetation will also be damaged, and the roots and leaves will be damaged, resulting in stunted development. And lead is in the atmosphere, drifting with the wind, and everywhere it goes, it is damaged.
In the human body, lead is particularly harmful. If children are exposed to lead, the development of the brain will be damaged, their wisdom will not be open, their reactions will be slow, and their studies will be difficult to progress. Adults touch lead, and their internal organs will be damaged. The liver is also a virus filter for the human body. If lead enters, the liver function will be disordered, and the ability to detoxify will be reduced. The kidneys are also invaded, and the excretion function is difficult, and toxins accumulate in the body. And lead can cause poor qi and blood, and people often feel tired and weak, and their complexion will turn yellow.
In contrast, selenium is an essential micro-substance for the human body. In the environment, selenium can help the soil to be fertile and beneficial to plant growth. Plants obtain selenium, which increases their disease resistance, and the fruit is full and delicious. In the human body, selenium has great power. It can resist oxidation, slow down the aging of the body, make the face moist, and the energy is not weak. It can also strengthen immunity, and evil poison is difficult to invade, and people rarely contract diseases. And selenium also has the ability to protect the cardiovascular vessels, making the
In summary, lead is a harmful substance and should be avoided; selenium is a beneficial substance and should be supplemented. In this way, it is in line with the way of health, ensuring the safety of the environment and the health of the human body.