Columbia Encyclopedia

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mortar, in building

(Encyclopedia)mortar, in building, mixture of lime or cement with sand and water, used as a bedding and adhesive between adjacent pieces of stone, brick, or other material in masonry construction. Lime mortar, a co...

mammary gland

(Encyclopedia)mammary gland, organ of the female mammal that produces and secretes milk for the nourishment of the young. A mammal may have from 1 to 11 pairs of mammary glands, depending on the species. Generally,...

mantle

(Encyclopedia)mantle, portion of the earth's interior lying beneath the crust and above the core. No direct observation of the mantle, or its upper boundary, has been made; its boundaries have been determined solel...

ultrasonics

(Encyclopedia)ultrasonics, study and application of the energy of sound waves vibrating at frequencies greater than 20,000 cycles per second, i.e., beyond the range of human hearing. The application of sound energy...

soup

(Encyclopedia)soup, liquid food in which different kinds of solid food have been cooked, e.g., meat, fish, fowl, vegetables, cereals, or fruit. Many soups are peculiar to certain localities, e.g., the pot-au-feu of...

xenon

(Encyclopedia)xenon zēˈnŏn [key] [Gr.,=strange], gaseous chemical element; symbol Xe; at. no. 54; at. wt. 131.293; m.p. −111.9℃; b.p. −107.1℃; density 5.86 grams per liter at STP; valence usually 0. Xeno...

nucleus, in physics

(Encyclopedia)nucleus, in physics, the extremely dense central core of an atom. Following the discovery of radioactivity by A. H. Becquerel in 1896, Ernest Rutherford identified two types of radiation given off b...

potassium

(Encyclopedia)potassium pətăsˈēəm [key], a metallic chemical element; symbol K [Lat. kalium=alkali]; at. no. 19; at. wt. 39.0983; m.p. 63.25℃; b.p. 760℃; sp. gr. .862 at 20℃; valence +1. Potassium is a s...

3D printer

(Encyclopedia)3D printer, computerized device that produces a three-dimensional object by creating it as a series of thin layers. The object is created from a model stored in computer-aided design file; the model i...

shaft sinking

(Encyclopedia)shaft sinking, excavation from the surface of an opening in the earth. Shafts, which are generally vertical, are usually distinguished from tunnels, which are horizontal. Little difficulty is experien...