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size of the "grains" is diminished. This is a potent argument against 

 all theories in which hysteresis is attributed to an arrangement of 

 atoms in a uniform space lattice. 



When a magnetic field is applied to an iron crystal in any direction 

 not parallel to one of the axes, the magnetization is not quite parallel 

 to the acting field. This manifests itself, for instance, when one 

 cuts a disc out of a crystal and exposes it to a magnetic field in its own 



Fig. 6— Magnetostriction of a single crystal of iron, magnetized parallel to 

 tetragonal, digonal, or trigonal axes. (After W. L. Webster.) 



plane; it cannot rest in equilibrium until it has so turned itself that 

 one of its three preferred directions lies parallel to the field, for other- 

 wise there is a component of the magnetic moment which suffers a 

 torque from the very field which evoked it. The angle between the 

 vectors I and H seldom attains and never exceeds twelve degrees; 

 when the field is kept constant in direction and varied in magnitude, 

 this angle of deviation is less for very weak and less for strong fields 

 than for some intermediate value of fieldstrength. In pyrrhotine, 



