(B) Touch the two new poles together to see whether they are like or unlike. (C) Test the nature of the poles with O C (Fig. 5) (D) Break one of the halves and test its parts. _=51. Discussion.=_ The above results agree with the theory that each molecule is a magnet (Exp. 18). No matter into how many pieces a magnet is broken, each part becomes a magnet. (Fig. 10). This shows that those molecules near the equator of the magnet really have magnetism. Their energy, however, is all used upon the adjoining molecules; hence no external bodies are attracted at that point. CHAPTER III. INDUCED MAGNETISM. [Illustration: Fig. 11.] =EXPERIMENT 24. To find whether we can magnetize a piece of iron without touching it with a magnet.= _Apparatus._ Horseshoe magnet, H M; iron filings, I F (Fig. 11). =52. Directions.= (A) Hold the armature of the magnet in a vertical position (Fig. 11), its lower end being directly in a little pile of iron filings. (B) Bring the N pole of H M near the upper end of A, but do not let them touch each other. (C) Keeping A and the pole of H M the same distance apart, lift them. Do any filings cling to A? (D) Without moving or jarring A, take H M away from it and note result upon the filings. _=53. Temporary Magnetism; Induced Magnetism.=_ The armature, A, was induced to become a magnet without even touching H M. Its magnetism was _temporary_, however, as the filings dropped as soon as the _inductive action_ of H M was removed. A small amount of residual magnetism (44) remained in A. Soft iron is exceedingly valuable, because it has very little retentivity (44), and because it can be easily _magnetized by induction_. The armature was made of soft iron. It had _induced magnetism_. It was a _temporary magnet_. =EXPERIMENT 25. To find whether a piece of steel can be permanently magnetized by induction.= _Apparatus._ An unmagnetized sewing-needle; horseshoe magnet, H M; iron filings; sheet of stiff paper. =54. Directions.= (A) Test the needle for magnetism. (B) Place the unmagnetized needle upon the paper, then move H M about immediately under it, so that the needle will be attracted. (C) Test the needle again for permanent magnetism. [Illustration: Fig. 12.] =EXPERIMENT 26. To study the inductive action of a magnet upon a piece of soft iron.= _Apparatus._ Horseshoe magnet, H M; iron filings, I F; a piece of soft iron wire about an inch long, I W (Fig. 12), placed upon the N pole of H M; compass, O C (No. 18), (§ 32). =55 Directions.= (A) Test the lower end of I W for magnetism with I F. (B) Leaving I W upon the N pole of H M, test the pole at the lower end of I W with O C, to determine whether it is N or S. (C) Jar I W (Exp. 19), then place it upon the S pole of H M, and again test the polarity of the lower end.