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chemical industry
(Encyclopedia)chemical industry, the business of using chemical reactions to turn raw materials, such as coal, oil, and salt, into a variety of products. During the 19th and 20th cent. technological advances in the...civil disobedience
(Encyclopedia)civil disobedience, refusal to obey a law or follow a policy believed to be unjust. Practitioners of civil disobedience usual base their actions on moral right and employ the nonviolent technique of p...fossil
(Encyclopedia)fossil, remains or imprints of plants or animals preserved from prehistoric times by the operation of natural conditions. Fossils are found in sedimentary rock, asphalt deposits, and coal and sometime...solid waste
(Encyclopedia)solid waste, discarded materials other than fluids. In the United States in 1996, nearly 210 million tons—about 4.3 lb. (2 kg) per person daily (up from 2.7 lb./1.2 kg in 1960)—were collected and ...algae
(Encyclopedia)algae ălˈjē [key] [plural of Lat. alga=seaweed], a large and diverse group of primarily aquatic plantlike organisms. These organisms were previously classified as a primitive subkingdom of the plan...clay
(Encyclopedia)clay, common name for a number of fine-grained, earthy materials that become plastic when wet. Chemically, clays are hydrous aluminum silicates, ordinarily containing impurities, e.g., potassium, sodi...calcium
(Encyclopedia)calcium kălˈsēəm [key] [Lat.,=lime], metallic chemical element; symbol Ca; at. no. 20; at. wt. 40.078; m.p. about 839℃; b.p. 1,484℃; sp. gr. 1.55 at 20℃; valence +2. Calcium is a malleable, ...Australopithecus
(Encyclopedia)Australopithecus ôstrāˌlōpĭthˈəkəs, –pəthēˈkəs [key], an extinct hominin genus found in Africa between about 4 and 1 million years ago. At least seven species of australopithecines are n...Germanic religion
(Encyclopedia)Germanic religion, pre-Christian religious practices among the tribes of Western Europe, Germany, and Scandinavia. The main sources for our knowledge are the Germania of Tacitus and the Elder Edda and...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...Browse by Subject
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