ELEMENTARY MAGNETISM. 271 



gainer by my own utterance, and by the reaction of your 

 fervor. The magnet also is the gainer by the reaction of 

 the body which it magnetizes. 



Look now to your excited piece of steel; figure euch 

 molecule with its opposed fluids spread over its opposite 

 faces. How can this state of things be permanent? The 

 fluids, by hypothesis, attract each other; what then, keeps 

 them apart? Why do they not instantly rush together 

 across the equator of the atom, and thus neutralize each 

 other? To meet this question philosophers have been 

 obliged to infer the existence of a special force, which 

 holds the fluids asunder. They call it coercive force; and 

 it is found that those kinds "of steel which oifer most 

 resistance to being magnetized which require the greatest 

 amount of "coercion" to tear their fluids asunder are the 

 very ones which offer the greatest resistance to the reunion 

 of the fluids, after they have been once separated. Such 

 kinds of steel are most suited to the formation of per- 

 manent magnets. It is manifest, indeed, that without 

 coercive force a permanent magnet would not be at all 

 possible. 



Probably long before this you will have dipped the end 

 of your magnet among iron filings, and observed how they 

 cling to it; or into a nail-box, and found how it drags the 

 nails after it. I know very well that if you are not the 

 slaves of routine, you will have J3y this time done many 

 things that I have not told you to do, and thus multiplied 

 your experience beyond what I have indicated. You are 

 almost sure to have caused a bit of iron to hang from the 

 end of your magnet, and you have probably succeeded in 

 causing a second bit to attach itself to the first, a third 

 to the second; until finally the force has become too feeble 

 to bear the weight of more. If you have operated with 

 nails, you may have observed that the points and edges 

 hold together with the greatest tenacity; and that a bit of 

 iron clings more firmly to the corner of your magnet than 

 to one of its flat surfaces. In short, you will in all likeli- 

 hood have enriched your experience in many ways without 

 any special direction from me. 



Well, the magnet attracts the nail, and the nail attracts 

 a second one. This proves that the nail nn contact with 

 the magnet has had the magnetic quality developed in it 

 by that contact. If it be withdrawn from the magnet its 



