Apparatus. Compass, O C (No. 18); a piece of soft iron wire, 6 in. (15 cm.) long (No. 15). Bend up about an inch of the wire at each end so that it may be firmly held when twisting it.
Note. You have seen that we can pound magnetism into or out of a piece of iron at will. Can we twist it into a wire and out again without the use of magnets?
94. Directions. (A) Test the wire for poles with O C.
(B) Hold the wire in a N and S direction, dipping it at the same time, as directed in [Exp. 47] for the poker, and twist it back and forth.
(C) Test again for poles with O C. As the poles of the wire may be very weak, bring them slowly toward the compass-needle (see [Exp. 14]), and note the first motions produced upon the needle.
(D) Hold the wire horizontally east and west, twist and test again. Has its magnetism become weaker or stronger than before?
EXPERIMENT 50. To test for magnetism in bars of iron, tools, etc.
Apparatus. Steel drills; files; chisels; bars or rods of iron that have been standing in an upright position; stove-lid lifters; stove pokers, etc., etc.; a compass.
95. Directions. (A) With the compass test the ends of the above for magnetism, and note which ends are S.