Abstract: To provide trimanganese tetraoxide having a high tap density and a uniform particle size distribution, and its production process. Trimanganese tetraoxide having a tap density of at least 1.5 g/cm3 and a relative standard deviation of the particle size of at most 40%. A process for producing such trimanganese tetraoxide, which comprises a step of mixing a manganese aqueous solution and an alkaline aqueous solution so that the oxidation-reduction potential is at least 0 mV and OH?/Mn2+ (mol/mol) is at most 0.55.

Abstract: To provide trimanganese tetraoxide having a high tap density and a uniform particle size distribution, and its production process. Trimanganese tetraoxide having a tap density of at least 1.5 g/cm3 and a relative standard deviation of the particle size of at most 40%. A process for producing such trimanganese tetraoxide, which comprises a step of mixing a manganese aqueous solution and an alkaline aqueous solution so that the oxidation-reduction potential is at least 0 mV and OH?/Mn2+ (mol/mol) is at most 0.55.

Abstract: The pneumatic radial tire comprises a carcass made of a ply of radially arranged cords toroidally extending between a pair of bead portions, a belt arranged outside the carcass in a radial direction of the tire, and a belt reinforcing layer of organic fiber cords arranged outside the belt in the radial direction of the tire, in which the organic fiber cord constituting the belt reinforcing layer has a strand construction and a twisting coefficient N.sub.t of 0.06-0.30 defined according to the equation.N.sub.t =T.times.(0.139.times.D/2.rho.).sup.1/2 .times.10.sup.-3 (1)whereinT: twisting number (turns/10 cm),D: total denier,.rho.: specific gravity (g/cm.sup.3).

Abstract: There is provided an improved electrophotographic image-forming method in which a image-bearing member is charged by brushing a surface of the image-bearing member with a magnetic brush of a charging material containing a magnetic carrier having a volume specific resistance of less than 10.sup.5 .OMEGA..multidot.cm. The present method causes no air pollution including generation of undesired by-products such as ozone, NOx, etc. The present method provides a toner image having high quality such as high resolution and high density without fogging on a background area of a recording sheet.

Abstract: A rotary telephone dial, in which at least one shaft is fixedly planted on a base plate. A rotary member is rotatably mounted on the shaft. Another base plate is engaged with the free end of the shaft to support the shaft. One direction assembling can be performed as a result of the above structure. A finger moving compensation mechanism is provided to obtain a sufficent allowable range of finger moving. The spring retaining structure and the governor mechanism are improved to effectively reduce the number of parts and to realize simplification of the manufacturing process.