Abstract: A hydrous silica gel is dehydrated by freezing, thawing, and removing water separated by thawing, thereby yielding silica particles. In addition, the silica particles thus formed is washed and fired, thereby producing a synthetic quartz glass power. A water glass is dealkalized, an oxidizing agent and an acid are added, the mixture thus formed is passed through a hydrogen type cation exchange resin, the aqueous silica solution thus formed is then gelled, and the gelled material is then washed and fired, thereby producing a synthetic quartz powder. Silica is sequentially held for a predetermined time at each temperature range of 150 to 400° C., 500 to 700° C., and 1,100 to 1,300° C., thereby producing a quartz glass.

Abstract: A hydrous silica gel is dehydrated by freezing, thawing, and removing water separated by thawing, thereby yielding silica particles. In addition, the silica particles thus formed is washed and fired, thereby producing a synthetic quartz glass power.

Abstract: A latent heat storage apparatus is provided and a latent heat storage solution therefor stores and retrieves a cool heat substantially in or from a latent heat thereof necessary for air conditioning, cooling, refrigerating, and so forth. The latent heat storage apparatus has an aqueous solution of a plurality of inorganic salts as a latent heat storage solution in a heat storage tank, formed to retrieve a cold heat from a stored latent heat, the latent heat storage apparatus. The latent heat storage solution is formed of (N-1) kinds of inorganic salts in at least an N-component aqueous solution where N.gtoreq.3. The latent heat storage solution stores the cold heat as the latent heat thereof. The cold heat is retrievable from the stored latent heat at a desired temperature almost invariably within a range higher than the N-component eutectic point and lower than any one of binary eutectic points of salts with water.

Abstract: A knocking sensor comprises a casing for receiving a pickup assembly including a transducer, which produces an electrical signal in accordance with engine vibrations, and a connector having at least a single pin electrically connected to the transducer. The casing comprises a threaded projection to be screwed in a screw hole of an engine, and a nut-like periphery to be rotated by a tool. The knocking sensor can be attached to the engine by means of an impact wrench, by rotating the nut-like portion. A plug connected to one end of a shielding code can be plugged in the connector to make an electrical connection between the transducer and a signal processing circuit after the knocking sensor has been attached to the engine, and therefore, the shielding code is prevented from being damaged during installation of the knocking sensor. The use of an impact wrench ensures secure attachment of the sensor, and reduces the installation time.