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rare-earth metals
(Encyclopedia)rare-earth metals, in chemistry, group of metals including those of the lanthanide series and actinide series and usually yttrium, sometimes scandium and thorium, and rarely zirconium. Promethium, whi...diesel engine
(Encyclopedia)diesel engine, type of internal-combustion engine invented by the German engineer Rudolf Diesel and patented by him in 1892. Although his engine was designed to use coal dust as fuel, the diesel engin...Burckhardt, Jacob Christoph
(Encyclopedia)Burckhardt, Jacob or Jakob Christoph yäˈkôp krĭsˈtôf bo͝orkˈhärt [key], 1818–97, Swiss historian, one of the founders of the cultural interpretation of history. He studied under Ranke at th...capacitor
(Encyclopedia)capacitor or condenser, device for the storage of electric charge. Simple capacitors consist of two plates made of an electrically conducting material (e.g., a metal) and separated by a nonconducting ...electrocardiography
(Encyclopedia)electrocardiography ĭlĕkˌtrōkärdēŏgˈrəfē [key], science of recording and interpreting the electrical activity that precedes and is a measure of the action of heart muscles. Since 1887, when ...lanthanum
(Encyclopedia)lanthanum lănˈthənəm [key] [Gr.,=to lie hidden], metallic chemical element; symbol La; at. no. 57; at. wt. 138.90547; m.p. about 920℃; b.p. about 3,460℃; sp. gr. 6.19 at 25℃; valence +3. Lan...boiling point
(Encyclopedia)boiling point, temperature at which a substance changes its state from liquid to gas. A stricter definition of boiling point is the temperature at which the liquid and vapor (gas) phases of a substanc...rubidium
(Encyclopedia)rubidium ro͞obĭdˈēəm [key], metallic chemical element; symbol Rb; at. no. 37; at. wt. 85.4678; m.p. 38.89℃; b.p. 686℃; sp. gr. 1.53 at 20℃; valence +1. Rubidium is a very soft silver-white ...acoustics
(Encyclopedia)acoustics əko͞oˈstĭks [key] [Gr.,=the facts about hearing], the science of sound, including its production, propagation, and effects. Various branches of acoustics that deal with different aspects...heating
(Encyclopedia)CE5 Typical warm-air heating system heating, means of making a building comfortably warm relative to a colder outside temperature. Old, primitive methods of heating a building or a room within it ...Browse by Subject
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