Abstract: A colored marker ink for use on a writing board is manufactured by blending a colorant, a resin and a mixed solvent consisting of a good solvent for the resin possessing a high speed of vaporization and a non-solvent for the resin possessing a lower speed of vaporization than that of the good solvent. When a letter or figure is written on the board with this marker ink, the resin component of the ink thus applied to the board gels into opaque lines in the shape of the letter or figure in consequence of gradual vaporization of the good solvent.

Abstract: An electrostatic holding and conveying apparatus having an endless belt member which comprises a base layer of soft, flexible insulative material and two groups of electrodes equally spaced and disposed on a first surface of the base layer. A protective layer of soft flexible semiconductive or insulative material is disposed on the first surface of the base layer to cover the electrodes. Two groups of terminals are provided on a second surface of the base layer and electrically connected to the two groups of electrodes, respectively. The endless belt extends between a drive roller and a driven roller with the second surface of the base layer in contact with the rollers. One of the rollers has two contact rings isolated from each other and supplied with a high DC voltage.