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allergy

(Encyclopedia)allergy, hypersensitive reaction of the body tissues of certain individuals to certain substances that, in similar amounts and circumstances, are innocuous to other persons. Allergens, or allergy-caus...

electromagnet

(Encyclopedia)CE5 Electromagnet electromagnet, device in which magnetism is produced by an electric current. Any electric current produces a magnetic field, but the field near an ordinary straight conductor is ...

spinal cord

(Encyclopedia)spinal cord, the part of the nervous system occupying the hollow interior (vertebral canal) of the series of vertebrae that form the spinal column, technically known as the vertebral column. Extending...

Burchfield, Charles

(Encyclopedia)Burchfield, Charles (Charles Ephraim Burchfield), 1893–1967, American painter, b. Ashtabula Harbor, Ohio, studied Cleveland School of Art. Living at first in Ohio, then moving (1921) to upstate New ...

pen

(Encyclopedia)pen, pointed implement used in writing or drawing to apply ink or a similar colored fluid to any surface, such as paper. Various kinds of pens have been used since ancient times. Reeds that were slit ...

hydrogen

(Encyclopedia)hydrogen hīˈdrəjən [key] [Gr.,=water forming], gaseous chemical element; symbol H; at. no. 1; interval in which at. wt. ranges 1.00784–1.00811; m.p. −259.14℃; b.p. −252.87℃; density 0.08...

clay

(Encyclopedia)clay, common name for a number of fine-grained, earthy materials that become plastic when wet. Chemically, clays are hydrous aluminum silicates, ordinarily containing impurities, e.g., potassium, sodi...

oxidation and reduction

(Encyclopedia)oxidation and reduction, complementary chemical reactions characterized by the loss or gain, respectively, of one or more electrons by an atom or molecule. Originally the term oxidation was used to re...

milling

(Encyclopedia)milling, mechanical grinding of wheat or other grains to produce flour. Milling separates the fine, mealy parts of grain from the fibrous bran covering. In prehistoric times grain was crushed between ...

diatom

(Encyclopedia)diatom dīˈətŏmˌ, –tōmˌ [key], unicellular organism of the kingdom Protista, characterized by a silica shell of often intricate and beautiful sculpturing. Most diatoms exist singly, although s...