MAGNETS. 189 



the upper ring upon your finger, and remove the magnet. The 

 force that separated the fluids in the molecules of the first ring and 

 held them apart is no longer present ; those fluids, therefore, rush 

 together. There is now no cause capable of holding apart the 

 opposite fluids in the molecules of the second ring, and they con- 

 sequently rush together ; and so in the case of each ring. 



(&.) Suspend an iron key from the positive end of a bar magnet. 

 The key is inductively magnetized, the relation of its poles to each 

 other and to the magnet being as shown in Fig. 125. A second 



FIG. 125. 



bar magnet of about the same power, with its poles opposite, is 

 moved along the first magnet. When the end of the second 

 magnet comes over the key, the key drops. The + pole of the 

 lower magnet attracted the and repelled the + of the key. The 

 pole of the upper magnet had an opposite effect, and as the two 

 magnets were of the same power, or nearly so, the separating influ- 

 ence became less than the mutual attraction of the opposite fluids, 

 which consequently reunited. This experiment goes to show that 

 when a magnetic body is attracted by a magnet, the attraction is 

 preceded ly polarization. 



313. Magnetic Curves. The inductive influence 

 of a magnet upon iron is not affected by the interposition 

 of any non-magnetic body. Over a good bar magnet place 

 a piece of card -board, upon which sprinkle iron filings; 

 tap the card-board lightly. The "magnetic curves" 

 (Fig. 126) thus formed are very interesting and instruc- 

 tive. The filings in any one of these curves are temporary 

 magnets with adjoining poles opposite and therefore attrac- 

 ting. By using two bar magnets placed side by side, first, 

 with like poles near each other, and, secondly, with unlike 



