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hearing

(Encyclopedia)hearing: see ear.

hearing aid

(Encyclopedia)hearing aid, device used in some forms of deafness to amplify sound before it reaches the auditory organs. Modern hearing aids are electronic. They contain a tiny receiver and a transistor amplifier, ...

process

(Encyclopedia)process, in law: see procedure.

Haber process

(Encyclopedia)Haber process häˈbər [key], commercial process for the synthesis of ammonia, NH3. Pure hydrogen and nitrogen gases are mixed in the appropriate proportion, heated to between 450℃ and 600℃, comp...

flotation process

(Encyclopedia)flotation process, in mineral treatment and mining, process for concentrating the metal-bearing mineral in an ore. Crude ore is ground to a fine powder and mixed with water, frothing reagents, and col...

Wacker process

(Encyclopedia)Wacker process, an industrial process for the manufacture of ethanol by oxidizing ethene. For example, bubbling ethylene and oxygen when treated by an acidified water solution of palladium and cupric ...

amalgamation process

(Encyclopedia)amalgamation process əmălˌgəmāˈshən [key], in particular, a method to extract gold and silver from ores. The ore is crushed and treated with mercury, in which the metal dissolves. The amalgam i...

Bessemer process

(Encyclopedia)CE5 Bessemer converter Bessemer process bĕsˈəmər [key] [for Sir Henry Bessemer], industrial process for the manufacture of steel from molten pig iron. The principle involved is that of oxidati...

Frasch process

(Encyclopedia)Frasch process fräsh [key] [for Herman Frasch, the German-American chemist who devised it], process for the extraction of sulfur from subsurface deposits. Three pipes, one inside another, are sunk to...

viscose process

(Encyclopedia)viscose process vĭsˈkōs [key], method widely used for the commercial preparation of rayon. Cellulose, prepared from either wood pulp or, less commonly, cotton linters, is treated with sodium hydrox...