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grinding

(Encyclopedia)grinding, process by which surface material is removed from an object, usually metal, by the abrasive action of a rotating wheel or a moving belt that contains abrasive grains. A grinding wheel can be...

sarin

(Encyclopedia)sarin zärēnˈ [key], volatile liquid used as a nerve gas. It boils at 147℃ but evaporates quickly at room temperature; its vapor is colorless and odorless. Chemically, sarin is fluoroisopropoxymet...

Red River, river, China and Vietnam

(Encyclopedia)Red River, Chinese Yuan Chiang, Vietnamese Song Hong, chief river of N Vietnam, 730 mi (1,175 km) long, rising in Yunnan prov., S China, and flowing southeast, in deep, narrow gorges, through N Vietna...

thorium

(Encyclopedia)thorium thôrˈēəm [key] [from Thor], radioactive chemical element; symbol Th; at. no. 90; mass number of most stable isotope 232; m.p. about 1,750℃; b.p. about 4,790℃; sp. gr. 11.7 at 20℃; va...

corundum

(Encyclopedia)corundum kərŭnˈdəm [key], mineral, aluminum oxide, Al2O3. The clear varieties are used as gems and the opaque as abrasive materials. Corundum occurs in crystals of the hexagonal system and in mass...

citric acid

(Encyclopedia)citric acid or 2-hydroxy-1,2,3-propanetricarboxylic acid, HO2CCH2C(OH)(CO2H)CH2CO2H, an organic carboxylic acid containing three carboxyl groups; it is a solid at room temperature, melts at 153℃, an...

nitroglycerin

(Encyclopedia)nitroglycerin nīˌtrōglĭsˈərĭn [key], C3H5N3O9, colorless, oily, highly explosive liquid. It is the nitric acid triester of glycerol and is more correctly called glycerol trinitrate. It is insol...

brownstone

(Encyclopedia)brownstone, red to brown variety of sandstone. Its unusual color is caused in some instances by the presence of red iron oxide which acts as a cement, binding the sand grains together. Vast thicknesse...

sodium silicate

(Encyclopedia)sodium silicate, any one of several compounds containing sodium oxide, Na2O, and silica, Si2O, or a mixture of sodium silicates. Sodium orthosilicate is Na4SiO4 (or 2Na2O·SiO2); sodium metasilicate i...

antimony

(Encyclopedia)antimony ănˈtĭmōˌnē [key] [Lat. antimoneum], semimetallic chemical element; symbol Sb [Lat. stibium,=a mark]; at. no. 51; at. wt. 121.760; m.p. 630.74℃; b.p. 1,750℃; sp. gr. (metallic form) ...