Columbia Encyclopedia

Search results

500 results found

helium

(Encyclopedia)helium hēˈlēəm [key], gaseous chemical element; symbol He; at. no. 2; at. wt. 4.0026; m.p. below −272℃ at 26 atmospheres pressure; b.p. −268.934℃ at 1 atmosphere pressure; density 0.1785 g...

eye

(Encyclopedia)CE5 Cross section of human eye eye, organ of vision and light perception. In humans the eye is of the camera type, with an iris diaphragm and variable focusing, or accommodation. Other types of ey...

mercaptan

(Encyclopedia)mercaptan thīˈōl [key], any of a class of organic compounds containing the group –SH bonded to a carbon atom. The volatile low-molecular-weight mercaptans have disagreeable odors. Mercaptans are ...

ionization chamber

(Encyclopedia)ionization chamber, device for the detection and measurement of ionizing radiation. It consists basically of a sealed chamber containing a gas and two electrodes between which a voltage is maintained ...

chemical analysis

(Encyclopedia)chemical analysis, the study of the chemical composition and structure of substances. More broadly, it may be considered the corpus of all techniques whereby any exact chemical information is obtained...

swim bladder

(Encyclopedia)swim bladder, large, thin-walled sac in some fishes that may function in several ways, e.g., as a buoyant float, a sound producer and receptor, and a respiratory organ. The swim bladder, or air bladde...

Whittle, Sir Frank

(Encyclopedia)Whittle, Sir Frank, 1907–96, English aeronautical engineer. Whittle was one of the first persons to associate the gas turbine with jet propulsion. Previously the gas turbine had been regarded as a m...

Anderson, Laurie

(Encyclopedia)Anderson, Laurie, 1947–, American performance artist, b. Chicago. Originally a sculptor, she was influenced by Philip Glass and other avant-garde composers in the early 1970s and soon turned to the ...

Chaetognatha

(Encyclopedia)CE5 Anatomy of an arrow worm, Sagitta, representative of the phylum Chaetognatha Chaetognatha kētôgnăthˈə [key], phylum of predominantly pelagic marine animals commonly known as arrowworms. A...

prostaglandin

(Encyclopedia)prostaglandin prŏsˌtəglănˈdən [key], any of a group of about a dozen compounds synthesized from fatty acids in mammals as well as in lower animals. Prostaglandins are highly potent substances th...