Columbia Encyclopedia

Search results

500 results found

delta

(Encyclopedia)delta [from triangular shape of the Nile delta, like the Greek letter delta], a deposit of clay, silt, and sand formed at the mouth of a river where the stream loses velocity and drops part of its sed...

grease

(Encyclopedia)grease, mixture of lubricant and thickener. It is used to reduce friction between surfaces from which oils would leak away or cause damage by dripping, or where lubrication must be assured for extende...

ovenbird

(Encyclopedia)ovenbird, common name for a member of the family Furnariidae, primitive passerine birds, which build elaborate, domed nests of clay or dig tunnels in the ground to lay their eggs. Ovenbirds are most c...

Nicaragua Canal

(Encyclopedia)Nicaragua Canal, proposed waterway between the Atlantic and the Pacific oceans. One often considered route would be 172.8 mi (278 km) long and would generally follow the San Juan River, then go throug...

cyclic compound

(Encyclopedia)cyclic compound, any one of a class of compounds whose molecules contain a number of atoms bonded together to form a closed chain or ring. If all of the atoms that form the ring are carbon, the compou...

land tax

(Encyclopedia)land tax, impost levied upon real property. It is sometimes called a real estate tax, especially when assessed against both improved and unimproved land. Probably the earliest direct tax and formerly ...

't Hooft, Gerardus

(Encyclopedia)'t Hooft, Gerardus, 1946–, Dutch theoretical physicist, Ph.D. Univ. of Utrecht, 1972. He has been a professor at the Univ. of Utrecht since 1977. 't Hooft shared the 1999 Nobel Prize in Physics with...

polycarbonates

(Encyclopedia)polycarbonates, group of clear, thermoplastic polymers used mainly as molding compounds (see plastic). Polycarbonates are prepared by the reaction of an aromatic difunctional phenol with either phosge...

Dacron

(Encyclopedia)Dacron dāˈkrŏn, dăkˈrŏn [key], trademark for a polyester fiber. Dacron is a condensation polymer obtained from ethylene glycol and terephthalic acid. Its properties include high tensile strength...

Berthollet, Claude Louis, Comte

(Encyclopedia)Berthollet, Claude Louis, Comte klōd lwē, kôNt bĕrtōlāˈ [key], 1748–1822, French chemist. His contributions to chemistry include the analysis of ammonia and prussic acid and the discovery of ...