Abstract: A rotary switch with a sealed enclosure in which a rotating knife-blade is housed cooperating with two stationary contacts supported by the internal periphery of the enclosure. A permanent magnet is incorporated in the stationary contacts to magnetically blow the arc roots on a curved migration track towards hidden locations which are not facing the knife-blade.The invention is applicable to a gas-insulated medium voltage switch.

Abstract: A method of producing mineral fillers containing hydrated calcium monocarboaluminate.Al(OH).sub.3, CaCO.sub.3 and Ca(OH).sub.2 are reacted together in the presence of water, the operating temperature range being of 50.degree. C.-100.degree. C. Although these materials are insoluble, a quick reaction occurs as well in a highly concentrated solid medium as in a diluted medium. According to a preferred embodiment, the amount of water is such to obtain a final dry matter content of 50%, and the substantially solid resulting paste is directly brought to the fluidity required for use by means of a defloculating agent.Application to paper coating.

Abstract: A binder for producing mortars or micro-concretes containing, by weight, 87% CPA 400 or CPA 500 cement, 13 to 19% aluminous cement and 0.1 to 1.0% of an organic agent. The mortars and micro-concretes prepared by means of said binder are adapted to spraying, in the moist state, or trowelling onto vertical, inclined or horizontal supports without any particular precautionary measure.

Abstract: The present invention relates to an improvement in the process of U.S. Pat. No. 4,002,484, making it possible to obtain ettringite in fiber form.According to the invention, the process is carried out in the same way as in U.S. Pat. No. 4,002,484 but with enough water to assure having a suspension containing a maximum of 25% dry matter at the end of the reaction, and in subjecting said suspension to moderate stirring of 1 to 5 times the force necessary to maintain a homogeneous suspension.Application to the replacement of asbestos fibers, notably as a fire-proof product.