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allotropy
(Encyclopedia)allotropy əlŏˈtrəpē [key] [Gr.,=other form]. A chemical element is said to exhibit allotropy when it occurs in two or more forms in the same physical state; the forms are called allotropes. Allot...white lead
(Encyclopedia)white lead, heavy, white substance, poisonous, insoluble in water, extensively used as a white pigment and base in paints. It is one of the oldest paint pigments used by humans. Chemically, it is basi...heterotroph
(Encyclopedia)heterotroph hĕtˈərətrōfˌ [key], living organism that obtains its energy from carbohydrates and other organic material. All animals and most bacteria and fungi are heterotrophic. In contrast, aut...air pollution
(Encyclopedia)air pollution, contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health. The major sources of air pollution are t...Pettenkofer, Max von
(Encyclopedia)Pettenkofer, Max von mäks fən pĕtˈənkōˌfər [key], 1818–1901, German chemist and hygienist. He studied medicine at Munich. Pettenkofer is considered a founder of epidemiology and is known for...law of simple multiple proportions
(Encyclopedia)law of simple multiple proportions, in chemistry, the statement that when two or more elements form more than one compound, the ratio of the weights of one element that combine with a given weight of ...Ikaría
(Encyclopedia)Ikaría or Icaria both: īkârˈēə [key], mountainous island, c.100 sq mi (260 sq km), SE Greece, one of the Southern Sporades, near Turkey. It has iron-ore deposits and sulfur springs. According to...Huelva
(Encyclopedia)Huelva wĕlˈvä [key], city, capital of Huelva prov., SW Spain, in Andalusia, on the Odiel R...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...pyrolusite
(Encyclopedia)pyrolusite pīˈrōlo͞ozīt [key], naturally occurring manganese dioxide, MnO2, a black mineral that crystallizes in the tetragonal system but is usually found in earthy or massive deposits. It is th...Browse by Subject
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