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ammonia

(Encyclopedia)ammonia, chemical compound, NH3, colorless gas that is about one half as dense as air at ordinary temperatures and pressures. It has a characteristic pungent, penetrating odor. Ammonia forms a minute ...

Pleistocene epoch

(Encyclopedia)Pleistocene epoch plīˈstəsēn [key], 6th epoch of the Cenozoic era of geologic time (see Geologic Timescale, tablegeologic timescale, table). According to a classification that considered its depos...

sewerage

(Encyclopedia)sewerage, system for the removal and disposal of chiefly liquid wastes and of rainwater, which are collectively called sewage. The average person in the industrialized world produces between 60 and 14...

ring, in astronomy

(Encyclopedia)ring, in astronomy, relatively thin band of rocks and dust and ice particles that orbit around a planet in the planet's equatorial plane. All four of the giant planets in the solar system—Jupiter, S...

energy, sources of

(Encyclopedia)energy, sources of, origins of the power used for transportation, for heat and light in dwelling and working areas, and for the manufacture of goods of all kinds, among other applications. The develop...

forest

(Encyclopedia)forest, a dense growth of trees, together with other plants, covering a large area of land. The science concerned with the study, preservation, and management of forests is forestry. A forest is an ec...

forgery, in art

(Encyclopedia)forgery, in art, the false claim to authenticity for a work of art. A forger often unconsciously produces a confusion of styles or subtly accents elements reflecting contemporary bias. A major examp...

smoking

(Encyclopedia)smoking, inhalation and exhalation of the fumes of burning tobacco in cigars and cigarettes and pipes; in the 21st cent., vaping, the similar use of e-cigarettes, also has become common. Some persons ...

salt, chemical compound

(Encyclopedia)salt, chemical compound (other than water) formed by a chemical reaction between an acid and a base (see acids and bases). Salts are also prepared by methods other than neutralization. A metal can c...

periodic table

(Encyclopedia)CE5 periodic table, chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley. In the periodic table the elements are arrange...