The artificial magnetization method was invented by the working people in ancient China through long-term production practice and repeated experiments, and it is a leap in the history of the development of magnetism and geomagnetism.
Emperor Wu of the Han Dynasty was a good fairy, so there were many famous magicians in the Han Dynasty. At that time, there was an alchemist named Luan Da, who liked to talk big and didn't even blink when he was bragging.
One day, Luan Da said to Emperor Wu of the Han Dynasty, "I once went out to sea and met a fairy. These immortals all hide fairy medicine, and people can live forever after eating it. "
Emperor Wu of the Han Dynasty was skeptical about Luan Da's words. Luan Da volunteered to perform a little magic trick first, so that Emperor Wu of the Han Dynasty could recognize himself and open his eyes.
Luan Da plays chess. He mixed chicken blood, iron filings and magnets in advance, tamped them and painted them on the chess pieces. During the performance, he put the chess pieces on the chessboard and muttered to himself on purpose. Due to the magnetic attraction, the chess pieces kept hitting each other.
Emperor Wu of the Han Dynasty and the people present were dazzled and thought it was driven by divine power, so they couldn't help cheering. So he worshipped Luan Dawei as the "General of Five Benefits" and asked Luan Dawei to go to the East China Sea to ask the immortals for the elixir of life.
Anxious Emperor Wu asked Luan Da when he would enter the sea.
Luan Da didn't dare to risk his life to go to the sea, so he went to Taishan to handle affairs.
Luan's ability to cheat Emperor Wu of the Han Dynasty is really unique. He can make the pieces collide with each other under the traction of a magnetic bar, but it also shows that he knows a lot about magnets.
In fact, the method used by Luan Dadou Qi is one of the artificial magnetization methods recorded in ancient books, that is, the "magnetic powder gluing method".
The ancients knew and used magnets for a long time and mastered some methods of artificial magnetization. There are basically three kinds of records about artificial magnetization in ancient books in China: magnetic powder bonding, geomagnetic induction and friction magnetic transmission.
Magnetic powder bonding method began in Han Dynasty. Huainan Wanbi Book of the Western Han Dynasty said that "cishi moves chess", and its practice is to use chicken blood to grind the needle, and the mixture of chicken blood and iron powder obtained during the needle grinding is mixed with magnet powder and coated on the surface of the chess piece. Put it on the chessboard after drying, and the pieces will attract or repel each other.
Obviously, this chess piece has become an artificial magnet.
Theoretically, every magnetic powder has polarity, and adding iron filings can greatly enhance the magnetic domain. Stick the magnetic powder and iron powder on the chess piece and put it in the geomagnetic field to dry slowly. In the process of drying, each magnet and iron particles should be arranged regularly along the geomagnetic induction line, and the chess pieces will show polarity, which can attract or repel magnets.
Zhuang Chuo in the Southern Song Dynasty once wrote in Chicken Ribs: "When you pound a magnet, you will wipe each half of the ladle with glue." "Take two spoons for an experiment, one or two feet apart, but jump up and turn up and down."
Fang Yizhi in the Ming Dynasty also recorded similar things. On the whole, artificial magnets made of magnetic powder glue may indeed be used in ancient times.
The most typical application of geomagnetic induction method is the method of making guide fish described in Jing Zong Yao written by Wu in Northern Song Dynasty. This geomagnetic induction method is the earliest practice of artificial magnetization in the world.
The principle of this method is as follows: firstly, the iron leaf fish is burned red, so that the kinetic energy of the molecules in the iron leaf fish is increased, and thus the molecular magnetic domain is changed from the original fixed state to the dynamic state.
Secondly, the iron fish must be cooled in the north-south direction when entering the water, and then magnetized. Now the analysis is reasonable. Because this can make the fish closer to the direction of geomagnetic field and make maximum use of geomagnetic induction. It can be seen that the existence of geomagnetic dip angle has been realized here.
Thirdly, "dipping in the pot without stopping at the tail" makes it cool rapidly and fixes the regular arrangement of molecular magnetic domains, which is also a quenching process.
Finally, when the fin guide fish is not used, it should be placed in an iron closed box to form a closed magnetic circuit to avoid magnetization loss, or placed next to a natural magnet in a certain direction to continue magnetization.
This magnetization method is entirely based on experience, but it is an important link in the development of magnetism and geomagnetism, which is more than 400 years earlier than the same magnetization method in Europe.
The magnetism obtained by artificial magnetization using geomagnetic field is still relatively low, which limits the practical value of this artificial magnet. Later, people invented the friction magnetic transfer method. This method of artificial magnet was first seen in Shen Kuo's Meng Qian Bi Tan in the Northern Song Dynasty.
Shen Kuo's "Meng Qian Bi Tan" said: "The Fang family can be guided by a magnet grinding needle." In other words, people who specialize in physics can make iron needles magnetic by rubbing their heads with magnets. This method is simple and easy, and its discovery and popularization have played an important role in the acquisition and application of magnets, first of all, the production and application of compasses, and its value is immeasurable.
Before the modern electromagnet appeared, almost all compasses were made in this way. Until today, this method is still in use.
In the west, it was not until A.D. 1200 that the method of making a compass by rubbing an iron needle with a natural magnet was recorded in Pingdingshan, which was more than a century later than that recorded by Shen Kuo in the Northern Song Dynasty.
Due to the deepening understanding of the properties of magnets and the invention of artificial magnets, the application of magnets is possible. Magnets were widely used in ancient times. In addition to the magnetic guide mentioned above, magnets are also used in the military.
During the period of Emperor Wu of Jin Dynasty, Bald Tree, the leader of Xianbei, was able to capture Liangzhou. Emperor Wu of Jin named Malone to protect the enemy. After Malone was ordered, magnets were piled up on both sides of the road to attract and block the functional parts of the bald tree wearing armor, making it difficult to move. The Jin army, on the other hand, armored with rhinoceros armour, advanced and retreated freely. Ma Longjun fought thousands of miles to kill bald trees, and Liangzhou was pacified. Whether it is true or not that Malone used magnets to attract and resist armored enemy forces remains to be verified, but at least it can be regarded as a design idea.
In production, magnets are used in ceramics, pharmaceuticals and other processes to absorb the iron filings mixed in raw materials to ensure the purity and whiteness of products.
China is the first country in the world to use magnetic therapy to treat diseases. In BC 180, Sima Qian, a historian of the Han Dynasty, wrote in Historical Records? "Biography of Bian Que Cang Gong" records: "The King of Qi was ill, so he sent for a doctor, refined five stones and presented them. Those who are not spicy in his mouth can't even take five stone heads. " Among them, "five stones" refer to magnets, realgar, green, cinnabar and bletilla.
The above historical facts show that China took the lead in understanding and applying magnets in the world for a long time in ancient times.