Abstract: In a ceramic wall or floor covering consisting of single tile-shaped elements which are designed to be electrically conductive, the electrical voltage is dissipated via the flanks of the tile-shaped ceramic element and via electrically conductive elements laid on the tile plane.

Abstract: A method for making pencil leads without firing includes taking mixtures of graphite and MgO which are made of Mg salts with MgCl.sub.2 solutions, forming such mixtures into desired shapes (crayons or pencil leads) and hardening them at room temperatures. Colored pencil leads are produced by processing MgO with inorganic or organic colors together with slip additives and MgCl.sub.2 solutions into pressable pastes, and then forming them into leads or crayons for room temperature hardening. To increase breakage resistance, the resulting leads or crayons are encased in wood. The MgCl.sub.2 solutions are mixtures of Sorel's cement, and the slip additive is talcum.

Abstract: The invention is concerned with the production of pencil leads and also pencil leads as produced by the proposed method. In accordance with the invention, graphite, enamel frit and quartz flour, preferably at least approximately in a ratio of one part of graphite, two to four parts of enamel frit and one part of quartz flour, are processed to form a starting mixture which is then pressed into the form of a lead, is dried and is fired. The invention renders it possible to perform sintering below a temperature of 550.degree. C. and, accordingly, to perform the sintering firing operation in a normal oxidizing atmosphere.

Abstract: For producing uneven coloring on firing plate-like ceramic material such as tiles or flags in a kiln, more specially a roller kiln, made up of preheating, firing and cooling zones, and through whose oxidizing atmosphere in the firing zone the material to be fired is moved in a single layer without burning tools for supporting it, in or at the end of the firing zone, in a screened-off part of the kiln, the material to be fired is acted upon by a partly reducing atmosphere. In this respect the material to be fired may be passed at this position through a reducing zone and then through a pulsating oxidation zone. It is however possible as well for the material to be fired to be moved through a reducing zone and then purposefully acted upon by blowing with a strongly oxidizing gas. A further possible way of undertaking the process is such that in or at the end of the firing zone the material to be fired is moved in a pulsating reducing zone.