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Roanne

(Encyclopedia)Roanne rôänˈ [key], town (1990 pop. 42,848), Loire dept., E central France, on the Loire River. Cotton and metals are the chief products; other industries include tanning, machine and vehicle manuf...

calcination

(Encyclopedia)calcination kălˌsənāˈshən [key], in metallurgy, process of heating solid material to drive off volatile chemically combined components, e.g., carbon dioxide. It is sometimes a step in the extrac...

superconductivity

(Encyclopedia)superconductivity, abnormally high electrical conductivity of certain substances. The phenomenon was discovered in 1911 by Heike Kamerlingh Onnes, who found that the resistance of mercury dropped sudd...

radium

(Encyclopedia)radium rāˈdēəm [key] [Lat. radius=ray], radioactive metallic chemical element; symbol Ra; at. no. 88; mass number of most stable isotope 226; m.p. 700℃; b.p. 1,140℃; sp. gr. about 6.0; valence...

hallmark

(Encyclopedia)hallmark, mark impressed on silverwork or goldwork to signify official approval of the standard of purity of the metal, also called plate mark. The hallmark was introduced by statute in England in 130...

Fréjus

(Encyclopedia)Fréjus frāzhüsˈ [key], town, Var dept., SE France. With adjoining Fréjus-Plage, located ...

Guéret

(Encyclopedia)Guéret gārāˈ [key], town, capital of Creuse dept., central France. It is a market center ...

galena

(Encyclopedia)galena gəlēˈnə [key] or lead glance, lustrous, blue-gray mineral crystallizing usually in cubes, sometimes in octahedrons. It is the most important ore and the principal source of lead. It consist...

Chełm

(Encyclopedia)Chełm khĕlm [key], Rus. Kholm, city, Lubelskie prov., E Poland. It is a railway junction an...

Chieti

(Encyclopedia)Chieti kyĕˈtē [key], city, capital of Chieti prov., Abruzzi region, central Italy, on the ...