Abstract: To provide a pipe joint which can be easily assembled and can maintain the connection of pipes firmly while simplifying the pipe connecting work. Tapered surfaces 6 which reduce in diameter toward openings 2 are formed on inner peripheral portions of half portions of a tube 1 in order to join pipes A and B together, and a diameter-reducible elastic wedge ring 7 is disposed on the large inside diameter portion of the tapered surface 6. In order that when the pipes A and B are about to slip out, the wedge rings 7 are pressed out along the tapered surfaces 6 to reduce a diameter thereof, rubber rings 10 capable of being placed in close contact with the pipes A and B are engaged with and held on sliding rings 8 capable of sliding smoothly along the inner periphery of the tube 1 and provided adjacent to the wedge rings 7. When the wedge rings 7 assume a diameter-reduced state, they are encroached on the outer peripheral surfaces of the pipes A and B to prevent the pipes from slipping out.

Abstract: Disclosed is a recording liquid comprising a carbon black dispersed in an aqueous medium, which is characterized in that a toluene extract of the carbon black has an absorbance of 0.05 or less at .lambda.max within the range of from 330 nm to 340 nm or at 337.5 nm when the toluene extract does not have .lambda.max within the range of from 330 nm to 340 nm. The recording liquid can be used in ink-jet recording in high safety. During and after long storage of the recording liquid, the carbon black does not precipitate out. Using the recording liquid, reliable recording can be attained with good jettable durability of the liquid. Even when the recording liquid is recorded onto ordinary papers, high-quality images with good water-fastness and good light-fastness can be formed. The recording liquid is especially suitable for thermal ink-jet recording systems.

Abstract: In an anisotropic polymeric magnet in tubular form, the magnetization orientation is directed in one direction perpendicular to the axial line of the tubular magnet. In a bipolar anisotropic magnet in tubular form, the magnetic poles can be formed only at symmetrical portions of the magnet with respect to the axial line and an imaginary line connecting the magnetic poles with each other is parallel to said one direction.In order to symmetrically distribute the magnetism around a tubular bipolar anisotropic magnet, a weld line(s) formed by injection molding of a mixture of ferromagnetic material powder and polymeric material is located in the portion(s) of the magnet where the magnetic poles are not formed.

Abstract: A rubber or plastic magnet of high magnetic properties is produced by incorporating a magnetoplumbite type magnetic powder into a rubber or thermoplastic or thermosetting matrix at a high concentration with a high degree of orientation of the magnetic particles. Such high concentration and orientation can be obtained by using a magnetoplumbite type magnetic powder having a compressed density in the range between 3.30 g/cm.sup.3 and about 3.55 g/cm.sup.3 and an average particle size of about 1.00 and 1.50.mu., said particles being prepared by dry crushing process from coarse sintered particles and having predominantly single crystal structure.