Magnetic Record

General Electric Co.'s laboratories in Schenectady last week demonstrated (see cut, p. 23) a tiny magnet, about the size of a pellet of buckshot, holding aloft a five pound flatiron. The magnet weighs about one-sixteenth of an ounce. The maximum ratio of lifted load to magnet weight is 1,500 to i, highest in the annals of engineering. Thus General Electric's mighty mite is the most powerful permanent magnet on record.

It is made of an aluminum-nickel-cobalt-iron alloy called "Alnico," announced some years ago by General Electric (TIME, Nov. 4, 1935). The first researches on its magnetic properties were by Professor T. Mishima of Tokyo Imperial University. Alnico has come into wide use in motors, radios and amplifiers, blowout fields, and in other apparatus where electromagnets (temporary magnets which lose their drawing power when the current which activates them is shut off) are not suitable.

Permanent magnets are magnetized by electrically coercing the molecules into alignment. The "pull" results because the north poles of the molecules all face in one direction, the south poles in the opposite direction.

Before the development of Alnico and other "age-hardening" alloys like it, permanent magnets were all quenched steels. In the newer alloys "magnetic hardness" is obtained by slow, controlled cooling. They provide more magnetic force at lower cost. The increased power of the Alnico magnet shown last week, designed by Physicist Wayne E. (for nothing) McKibben, is due to a steel sheath around it, which efficiently concentrates the magnetic flux very much as an optical lens focuses rays of light.

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