Columbia Encyclopedia

Search results

500 results found

cheese

(Encyclopedia)cheese, food known from ancient times and consisting of the curd of milk separated from the whey. The numerous cheeses (often named for their place of origin) depend for their distinctive qualities ...

diffusion

(Encyclopedia)diffusion, in chemistry, the spontaneous migration of substances from regions where their concentration is high to regions where their concentration is low. Diffusion is important in many life process...

engineering

(Encyclopedia)engineering, profession devoted to designing, constructing, and operating the structures, machines, and other devices of industry and everyday life. Until the Industrial Revolution there were only t...

stellar structure

(Encyclopedia)stellar structure, physical properties of a star and the processes taking place within it. Except for that of the sun, astronomers must draw their conclusions regarding stellar structure on the basis ...

synthetic elements

(Encyclopedia)synthetic elements, in chemistry, radioactive elements that were not discovered occurring in nature but as artificially produced isotopes. They are technetium (at. no. 43), which was the first element...

sodium chloride

(Encyclopedia)sodium chloride, NaCl, common salt. Salt is important in many ways. It is an essential part of the diet of both humans and animals and is a part of most animal fluids, such as blood, sweat, and te...

photographic processing

(Encyclopedia)photographic processing, set of procedures by which the latent, or invisible, image produced when a photographic film is exposed to light is made into a permanent visible image. The negative may b...

botany

(Encyclopedia)botany, science devoted to the study of plants. Botany, microbiology, and zoology together compose the science of biology. Humanity's earliest concern with plants was with their practical uses, i.e., ...

Thatcher, Margaret Hilda Roberts Thatcher, Baroness

(Encyclopedia)Thatcher, Margaret Hilda Roberts Thatcher, Baroness, 1925–2013, British political leader. Great Britain's first woman prime minister, nicknamed the “Iron Lady” for her uncompromising political s...

compound

(Encyclopedia)compound, in chemistry, a substance composed of atoms of two or more elements in chemical combination, occurring in a fixed, definite proportion and arranged in a fixed, definite structure. A compound...