Abstract: A coating composition for thick coating prepared by adding an aggregate to a coating liquid containing 5 to 40% by weight as SiO.sub.2 of a coloidal silica and 3 to 40% by weight of disolved and/or finely dispersed organic polymer, having an SiO.sub.2 /M.sub.2 O mole ratio (in which M is a monovalent alkali metal atom) of at least 7, and having a viscosity lower than 100 c.p. at 20.degree. C. when kept in the sealed state at 50.degree. C. for 10 days.Said coating composition being especially suitable for coating of 1-20 kg/m.sup.2 in thickness and storable for a long period of time with an excellent stability, giving a cured coating having high water resistance, good weather resistance, high adhesive strength and no efflorescence in its surface.

Abstract: An equalizer amplifier of a negative feedback type comprises a common-emitter amplifier, an emitter follower amplifier cascade-connected thereto, and a negative feedback network connected between the output terminal of the emitter follower amplifier and the input terminal of the common-emitter amplifier with its negative feedback level increased as the frequency increases, wherein an inductance element is connected in series with the negative feedback circuit to attenuate harmful signals whose frequencies are higher than those of audio signals, thereby making large the ratio of signal to noise in the equalizer amplifier.

Abstract: A coating composition for building materials which comprises 100 parts by weight of a quaternary ammonium silicate having a silica content, calculated as SiO.sub.2, of 5 to 70% by weight, 2 to 200 parts by weight of a metal oxide and/or hydroxide capable of converting silica sol to silica gel and water in an amount sufficient to plasticize said composition.

Abstract: Calcium silicate monohydrate (2CaO.sup.. SiO.sub.2.sup.. H.sub.2 O) can be produced in a coating which has been formed by a coating material containing silica sol alone or silica sol and other additives such as aggregate, viscosity increasing agent, etc. by subjecting the coating to a chemical treatment such as heat-treatment, ultra-violet ray irradiation treatment, etc. in the presence of water and a calcium compound which may be present either in the coating material, or in the treating liquid, or in an object to be coated. The film which contains the calcium silicate monohydrate produced by said chemical treatment has remarkably high hardness and is excellent in water-resistance, water-imperviousness, weather-resistance, and heat-resistance.

Abstract: A coating composition for thick coating prepared by adding an aggregate to a coating liquid containing 5 to 40% by weight as SiO.sub.2 of a coloidal silica and 3 to 40% by weight of dissolved and/or finely dispersed organic polymer, having an SiO.sub. 2 /M.sub.2 O mole ratio (in which M is a monovalent alkali metal atom) of at least 7, and having a viscosity lower than 100 c.p. at 20.degree. C when kept in the sealed state at 50.degree. C for 10 days.Said coating composition being especially suitable for coating of 1 - 20 kg/m.sup.2 in thickness and storable for a long period of time with an excellent stability, giving a cured coating having high water resistance, good weather resistance, high adhesive strength and no efflorescence in its surface.

Abstract: A refractory composition comprises a basic refractory raw material such as oxides or hydroxides of magnesium, calcium, chromium or maganese, quaternary ammonium hydroxide and silica sol and/or silicate. The composition is used to prepare unfired refractories having a high compression strength by merely molding and drying it without the necessity of firing. When fired, it manifests comparable compression strength. The composition can also be used as monolithic refractory, refractory mortar, refractory coating agent, mold release, etc.