CHAPTER XI 

 MAGNETISM AND ELECTRICITY 



Magnets. Many years ago it was observed that an 

 occasional piece of ore possessed the property of attract- 

 ing small bits of iron and steel. It was also observed 

 that the pieces of iron and steel which were rubbed with 

 this ore acquired the same property. This strange ore 

 is -known as magnetite and probably derived its name from 

 Magnesia, a province of Asia Minor in which the ore is 

 quite abundant. The ore is also found in Norway, Sweden, 

 and in the American continent. Pieces of ore which 

 possess this property of attraction are called lode stones 

 or natural magnets. Pieces of steel which have acquired 

 the property of attracting other pieces of iron and steel, 

 by being stroked with natural magnets, are called artificial 

 magnets. Artificial magnets may also be made by pass- 

 ing an electric current around bars of steel. More will 

 be said about this method later. 



Experiment 50. Rub a knife blade or small piece of steel 

 against a bar magnet. Now bring the knife blade near some iron 

 filings. Has it acquired the power^to attract bits of iron? What 

 kind of magnet is it? 



Law of Magnetic Poles. If iron filings are sifted over 

 a magnet, it will be observed that the filings cling in a 

 large bunch at each end of the magnet, but in the middle 

 of the bar scarcely any filings will cling. These centers 

 of attraction are called the poles of the magnet. The 



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