(Encyclopedia) Quebec campaign, 1775–76, of the American Revolution. The Continental Congress decided to send an expedition to Canada to protect the northern frontier from British attack and to…
(Encyclopedia) Vicksburg campaign, in the American Civil War, the fighting (Nov., 1862–July, 1863) for control of the Mississippi River. The Union wanted such control in order to split the…
(Encyclopedia) cyanide process or cyanidation, method for extracting gold from its ore. The ore is first finely ground and may be concentrated by flotation; if it contains certain impurities, it may…
(Encyclopedia) amalgamation processamalgamation processəmălˌgəmāˈshən [key], in particular, a method to extract gold and silver from ores. The ore is crushed and treated with mercury, in which the…
(Encyclopedia) Frasch processFrasch processfräsh [key] [for Herman Frasch, the German-American chemist who devised it], process for the extraction of sulfur from subsurface deposits. Three pipes, one…
(Encyclopedia) Haber processHaber processhäˈbər [key], commercial process for the synthesis of ammonia, NH3. Pure hydrogen and nitrogen gases are mixed in the appropriate proportion, heated to…
(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…
