The instability of the particle distribution on the Preisach diagram increases markedly with the increasing squareness ratio

and the packing density of fine magnetic particles. This fact means that the instability of particle distribution is closely related to the existence of the strong interaction field which depends on the intensity of the magnetization of the medium. To obtain the intrinsic or stable particle distribution, the effective field strength acting in the medium has been expressed in terms of the interaction field which should be called the Onsager field. Furthermore, the effect of the interaction field on the process of anhysteretic magnetization was interpreted on the modified Preisach diagram.