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ELEMENTARY PHYSICS.
[§ 251
forces between the molecules maintain equilibrium in the molecular groups after the magnetizing force has fallen below the value at which they were formed; sufficient reduction of the magnetizing force at last occasions a breaking down of these groups and permits the formation of new ones, which exert less external magnetic force. During the time in which this change in grouping occurs, the intensity of magnetization diminishes rapidly; it does not, however, vanish until the magnetizing force has attained a finite negative value. From this point on, changes similar to those already described go on in the reverse sense. Ewing's theory also explains very well all the facts explained by Weber's form of the theory.
