72 ELEMENTARY LESSONS ON [CHAP. n. 



CHAPTER II. 



MAGNETISM. 



LESSON VIII. Magnetic Attraction and Repulsion. 



76. Natural Magnets or Lodestones. The 



name Magnet (Magnes Lapis) was given by the 

 ancients to certain hard black stones found in various 

 parts of the world, notably at Magnesia in Asia Minor, 

 which possessed the property of attracting to them small 

 pieces of iron or steel. This magic property, as they 

 deemed it, made the magnet-stone famous ; but it was 

 not until the tenth or twelfth century that such stones 

 were discovered to have the still more remarkable pro- 

 perty of pointing north and south when hung up by 

 a thread. This property was turned toi advantage in 

 navigation, and from that time the magnet received the 

 name of Lodestone 1 (or "leading- stone"). The 

 natural magnet or lodestone is an ore of iron, known to 

 mineralogists as magnetite and having the chemical 

 composition Fe 3 O 4 . This ore is found in quantities in 

 Sweden, Spain, Arkansas, the Isle of Elba, and other 

 parts of the world, though not always in the magnetic 

 condition. It frequently occurs in crystals ; the usual 

 form being the regular octahedron. 



77. Artificial Magnets. If a piece of iron, or, 

 better still, a piece of hard steel, be rubbed with a lode- 

 stone, it will be found to have also acquired the properties 

 characteristic of the magnet ; it will attract light bits of 



1 The common spelling loadstone is due to misapprehension. 



