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12. To ij cli a wire in the middle with one pole of the 

 stone, and the pole of the wire will be in that place, 

 the two ends will IK the other pole. 13. The poles 

 of a small loadstone may piesently be changed, by 

 applying them to the opposite poles of a large one. 



14. lion bars which stand lung in an erect posifion, 

 grow permanency magnctical ; the lower end of them 

 being the north pole, and the upper the south pole. 



15. The same effect follows, il you only hold them 

 perpendicularly ; but if you invert them, the poles 

 will shift their places. 16. Fire, which deprives a 

 loadstone of its attractive virtue, soon gives verticity 

 to a bar of iron, if it be heated red hot, and then 

 cooled in an erect posture, or directly north and 

 south. 17. A piece of English oker thus heated and 

 cooled, acquires the same verticity. 18 The verti- 

 city thus acquired by a bar o kon, is destroyed by 

 two or three smart blows on the middle of it. 19. 

 Either a piece of iron or a loadstone being laid on 

 a cork that swims freely in the water, which ever 

 of the two is held in, the hand, the other will be drawn 

 to it. This proves that the iron attracts the stone, 

 just as much as it is attracted by it. 20. Draw a 

 knife leisurely from the handle to the point over one 

 of the poles of a loadstone, aud it acquires a strong 

 magnetic virtue. But this is immediately lost, if you 

 draw it over the same pole from the point to the 

 handle. Lastly, a loadstone acts with as great force 

 in vacuo, as in the open air. 



The chief laws of magnetism are these, 1. The 

 loadstone has both a attractive and a directive 

 power : iron touched by it has only the former. 2. 

 Iron seems to consist almost wholly of attractive par- 

 ticles, loadstones of attractive and directive together, 

 probably mixed with heterogeneous matter, as not 

 having been purged by fire like iron. And hence 

 iron, when touched, will lift up a much greater weight 

 than the loadstone tiiat touched it. 3. The attrac- 

 tive power of armed loadstones, is caeteris paribus, as 

 their surfaces. 4. Both poles oi the loadstone equally 



