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pollution allowance

(Encyclopedia)pollution allowance or emission rights, government-issued permit to emit a certain amount of a pollutant. The holder of the permit may use it to pollute legally, may trade permits, or may sell the per...

Laurent, Auguste

(Encyclopedia)Laurent, Auguste ōgüstˈ lōräNˈ [key], 1808–53, French organic chemist. He devised a systematic nomenclature for organic chemistry. His studies on naphthalene and its chlorination products led ...

rotary engine

(Encyclopedia)rotary engine, internal-combustion engine whose cycle is similar to that of a piston engine, but which produces rotary motion directly without any conversion from reciprocating motion. A major problem...

Young, Thomas

(Encyclopedia)Young, Thomas, 1773–1829, English physicist, physician, and Egyptologist. He established (1799) a medical practice in London and was elected (1811) to the staff of St. George's Hospital there. His l...

ether, in physics and astronomy

(Encyclopedia)ether or aether, in physics and astronomy, a hypothetical medium for transmitting light and heat (radiation), filling all unoccupied space; it is also called luminiferous ether. In Newtonian physics a...

sun, in astronomy

(Encyclopedia)CE5 Structure of the sun sun, intensely hot, self-luminous body of gases at the center of the solar system. Its gravitational attraction maintains the planets, comets, and other bodies of the sola...

Gerhardt, Charles Frédéric

(Encyclopedia)Gerhardt, Charles Frédéric shärl frādārēkˈ zhārärˈ [key], 1816–56, French chemist, b. Strasbourg. He revived the theory of acid radicals, which he called the theory of residues, and did va...

recoilless rifle

(Encyclopedia)recoilless rifle, light artillery piece, without recoil, usually operated by two men. An American invention, it was used as an infantry weapon for attacking fortifications such as pillboxes and bunker...

Helmont, Jan Baptista van

(Encyclopedia)Helmont, Jan Baptista van yän bäptĭsˈtä vän hĕlˈmônt [key], 1577–1644, Flemish physician, chemist, and physicist. He attributed physiological changes to chemical causes, but his conclusions...

Lucas, Robert Emerson, Jr.

(Encyclopedia)Lucas, Robert Emerson, Jr., 1937–2023, American economist, b. Yakima, Wash., Ph.D. Univ. of Chicago, 1964. Lucas taught at Carnegie Mellon Univ. (1963...