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bedbug

(Encyclopedia)bedbug, any of the small, blood-sucking bugs of the family Cimicidae, which includes about 30 species distributed throughout the world. Bedbugs are flat-bodied, oval, reddish brown, and about 1⁄4 in...

silica

(Encyclopedia)silica or silicon dioxide, chemical compound, SiO2. It is insoluble in water, slightly soluble in alkalies, and soluble in dilute hydrofluoric acid. Pure silica is colorless to white. It occurs in sev...

plasma

(Encyclopedia)plasma, in physics, fully ionized gas of low density, containing approximately equal numbers of positive and negative ions (see electron and ion). It is electrically conductive and is affected by magn...

vibration

(Encyclopedia)vibration, in physics, commonly an oscillatory motion—a movement first in one direction and then back again in the opposite direction. It is exhibited, for example, by a swinging pendulum, by the pr...

nickel

(Encyclopedia)nickel, metallic chemical element; symbol Ni; at. no. 28; at. wt. 58.6934; m.p. about 1,453℃; b.p. about 2,732℃; sp. gr. 8.902 at 25℃; valence 0, +1, +2, +3, or +4. Nickel is a hard, malleable, ...

Precambrian

(Encyclopedia)Precambrian, name of a major division of geologic time (see Geologic Timescale, tablegeologic timescale, table), from c.5 billion to 570 million years ago. It is now usually divided into the Archean a...

copper, chemical element

(Encyclopedia)copper, metallic chemical element; symbol Cu [Lat. cuprum=copper]; at. no. 29; at. wt. 63.546; m.p. 1,083.4℃; b.p. 2,567℃; sp. gr. 8.96 at 20℃; valence +1 or +2. Copper and some of its alloys ha...

fire

(Encyclopedia)fire, the phenomenon of combustion as seen in light, flame, and heat. One of the basic tools of human culture, its use is extremely ancient, predating the existence of Homo sapiens by several hundred ...

evaporation

(Encyclopedia)evaporation, change of a liquid into vapor at any temperature below its boiling point. For example, water, when placed in a shallow open container exposed to air, gradually disappears, evaporating at ...

Ericsson, John

(Encyclopedia)Ericsson, John ĕrˈĭksən [key], 1803–89, Swedish-American inventor and marine engineer, b. Värmlands co., Sweden. He moved to London in 1826, and entered the railroad locomotive Novelty in a con...