Abstract: A filtering apparatus is used to continuously separate a large quantity of a substance such as a slurry, sludge or other suspension into a liquid component and a solid component in such a manner that the separated solid component is obtained as a cake in a semi-dried condition, and comprises a rotary drum including a perforated cylindrical member and a filter cloth provided on the outer peripheral surface. The drum is supported for rotation so that a portion thereof is immersed into the substance to be filtered. The pressure within the drum is reduced by a vacuum pump so that the liquid component of the substance is drawn into the drum through the portion thereof is immersed into the substance while the solid component of the substance is accumulated on the filter cloth of the rotating drum and is held as a cake thereon. The cake is continuously removed by a doctor blade in the portion of the drum which is exposed to the atmosphere.

Abstract: A method of electrolytically etching a ferrite body wherein the body is immersed in an etching electrolyte of controlled concentration, an electrode is positioned in the electrolyte in spaced relation to the body, with the ratio of exposed surface area of the ferrite body and the confronting surface area of the electrode being within a predetermined range, and applying a unidirectional voltage between the ferrite body and the electrode, the ferrite body being at a negative voltage relative to the electrode for a sufficient time to cause the desired etching.

Abstract: A method of manufacturing a ferrite magnetic transducer head is disclosed, in which two Mn - Zn ferrite core blocks are bonded together with glass material containing Fe.sub.2 O.sub.3 and ZnO. By proper thermal treatment, homogeneous dispersion of fine precipitates of Zn - Fe - O is formed in the bonding glass.