(D) If you find that the needle is magnetized, rub its point upon the point of the other needle; then test the point of the second needle for magnetism.
21. Discussion; Bar Magnets. A piece of good steel will attract iron after merely touching a magnet. To thoroughly magnetize it, however, a mere touch is not sufficient. There are several ways of making magnets, depending upon the size, shape, and strength desired. For these experiments, the student needs only a good horseshoe magnet, or, better still, the electro-magnets described later; with these any number of small[10] magnets may be made. Straight magnets are called bar magnets.
EXPERIMENT 9. To make small magnets.
Apparatus. [Fig. 3]. The horseshoe magnet, H M; sewing-needles; iron filings. (See Apparatus Book, Pg. 140, for various kinds of steel suitable for small magnets.)
22. Directions. (A) Hold H M ([Fig. 3]) in the left hand, its poles being uppermost. Grasp the point of the needle with the right hand, and place its point upon the N or marked pole of H M.
(B) Pull the needle along in the direction of its length (see the arrow), continuing the motion until its head is at least an inch from the pole.
(C) Raise the needle at least an inch above H M, lower it to its former position ([Fig. 3]), and repeat the operation 3 or 4 times. Do not slide the needle back and forth upon the pole, and be careful not to let it accidentally touch the S pole of H M.
(D) Test the needle for magnetism with iron filings, and save it for the next experiment.
