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Unterwalden

(Encyclopedia)Unterwalden o͝onˈtərväldən [key], canton, central Switzerland, one of the Four Forest Cantons. A mountainous, forested, and chiefly pastoral region, Unterwalden is divided into the half cantons o...

bellflower, in botany

(Encyclopedia)bellflower or bluebell, name commonly used as a comprehensive term for members of the Campanulaceae, a family of chiefly herbaceous annuals or perennials of wide distribution, characteristically found...

pyridine

(Encyclopedia)pyridine ăzˈēn [key], C5H5N, colorless, flammable, toxic liquid with a putrid odor. It melts at −42℃ and boils at 115.5℃. Chemically, it is a heterocyclic aromatic tertiary amine (see under a...

flux, magnetic

(Encyclopedia)flux, magnetic, in physics, term used to describe the total amount of magnetic field in a given region. The term flux was chosen because the power of a magnet seems to “flow” out of the magnet at ...

surface chemistry

(Encyclopedia)surface chemistry, study of chemical reactions in which the reactants are first adsorbed onto a surface medium (see adsorption) that then acts as a catalyst for the reaction; after the reaction the pr...

species

(Encyclopedia)species, in biology, a category of classification, the original and still the basic unit in the demarcation of plant and animal types. The species marks the boundary between populations of organisms r...

Bolton, Herbert Eugene

(Encyclopedia)Bolton, Herbert Eugene, 1870–1953, American historian and teacher, b. Wilton, Monroe co., Wis. He taught history at the Univ. of Texas (1901–9), Stanford (1909–11), and the Univ. of California (...

apartment house

(Encyclopedia)apartment house, building having three or more dwelling units. Numerous early examples of this form of dwelling have been found in remains of Roman and medieval cities and in the 17th-cent. Pueblo vil...

sextant

(Encyclopedia)CE5 Sextant sextant, instrument for measuring the altitude of the sun or another celestial body; such measurements can then be used to determine the observer's geographical position or for other n...

Chichén Itzá

(Encyclopedia)Chichén Itzá chēchānˈ ētsäˈ [key], city of the ancient Maya, central Yucatán, Mexico. It was founded around two large cenotes, or natural wells. According to one system of dating, it was foun...