"No; in that case the bar should be of the softest iron. Remember, therefore, that for a permanent magnet, use the hardest steel, and for a temporary one, the softest iron."
"Then as we want to make a permanent magnet, must we harden both of the bars?"
"No; for our uses, one must be left soft, because on that we shall want to wind some insulated wire to make a temporary magnet."
The small amount of wire which was on hand was then coated with a thin layer of the ramie fiber, which was carefully wrapped around, so that the different layers of wire could not touch each other. When this was completed, a spool was constructed, which fitted over the little bar or rod, because they were rounded off, and one end of the soft iron rod extended out beyond the spool.
The opposite ends of the winding were then brought out and attached to the terminal wires of the battery. A test showed that the magnet thus made would readily pick up pieces of iron or steel. The Professor then took the hardened steel rod, through which a small hole had been bored, midway between its ends, and laying it down on the table, the projecting end of the temporary magnet which projected from the spool was put into contact with the hard steel rod, and slowly drawn along to the end. The soft bar magnet was then raised up and again repeated, as shown in the drawing (Fig. 20), where the dotted line (A) represents the movement of the end of the temporary magnet.
