CHAPTER XXV 

 MAGNETS 



161. Natural Magnet or Lodestone. The ancients 

 found a certain hard, black stone at Magnesia, in Asia 

 Minor, which they called a magnet. It had the property 

 of attracting small pieces of iron. They thought that 

 the stone possessed some magic property and it became 

 very famous. It was not discovered until about the 

 eleventh century that the famous magnet-stone would 

 take a north and south position when it was hung up by 

 a string. This property of the stone enabled men to 

 determine direction by its aid, hence it became useful 

 in navigation. From such uses of the stone it received 

 the name lodestone or "leading-stone." The natural 

 magnet is an iron ore called magnetite, which has the 

 chemical composition FesCX, an iron oxide. The ore is 

 found in quantities in Sweden, Spain, Arkansas, .and 

 other parts of the world, but not always in a magnetic 

 condition. 



162. Artificial Magnet. If a lodestone is rubbed over 

 a piece of hard iron, the iron will become magnetized 

 so that it will attract particles of iron in the same way as 

 the lodestone. The magnetized iron will also take a north 

 and south position when it is suspended by a thread. 

 As early as 1729 it was learned that steel will hold 

 magnetism much longer than iron. 



The illustration shows that the iron filings adhere in 

 a mass at the ends of the magnet instead of covering 



