The mystery of magnetic doors.The mystery of the magnetic doors According to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. Chinese legend, a tomb located near the town of Sian and belonging to the first emperor of the Ch'in dynasty Noun 1. Ch'in dynasty - the Chinese dynasty (from 246 BC to 206 BC) that established the first centralized imperial government and built much of the Great Wall Ch'in, Qin, Qin dynasty dynasty - a sequence of powerful leaders in the same family (221-206 BC) had a door that could not be cut with iron swords because the door magnetically attracted the iron. Moreover, in a newly discovered volume of an encyclopedia compiled in China in 1406, scholars found passages indicating that the gates of a nearby palace were also made of magnetic stone: "Warriors wearing iron armor were detained or attracted and could not pass through." Now scientists think they have a clue to the origin of this magnetic stone. In a letter appearing in the Feb. 13 NATURE, Tai Li-Chi of the Research Institute of Iron and Steel in Beijing reports that a colleague discovered that the sand along the banks of the Wei River Wei River River, north-central China. It rises in the mountains of southeastern Gansu province and flows east through Shaanxi province to join the Huang He (Yellow River). It is 537 mi (864 km) long. , which passes by Sian, can be used as ferrite fer·rite n. 1. Any of a group of nonmetallic, ceramiclike, usually ferromagnetic compounds of ferric oxide with other oxides, especially such a compound characterized by extremely high electrical resistivity and used in computer memory material with good magnetic properties. Tai analyzed the sands and found that they contain magnetite magnetite (măg`nətīt), lustrous black, magnetic mineral, Fe3O4. It occurs in crystals of the cubic system, in masses, and as a loose sand. and other magnetic oxides. "The quality of the material is not inferior to the synthetic oxides used in the manufacture of ferrite in modern industry," he says. But, he concludes, "we have not yet found any direct evidence that this magnetic sand was [indeed] used in ancient times." |
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