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reduce

a. To lower the oxidation state by adding electrons to a chemical species.
b. In general, to treat metallurgically for the production of metal.
Fay

reduced iron

Free iron in a fine state of division obtained by reducing ferric oxide by
heating it in a current of hydrogen. Also called iron by hydrogen, iron
powder, and spongy iron. Standard, 2; Fay

reduced level

Height above specified datum level of a surveyed point. Pryor, 3

reduced natural frequency

The natural frequency of vibration of a foundation at an average ground
pressure of unity is the reduced natural frequency divided by the square
root of the ground pressure. This relationship has been established by
Tschebotarioff. Hammond

reducing agent

a. A material that adds hydrogen to an element or compound.
McGraw-Hill, 1
b. A material that adds an electron to an element or compound; i.e.,
decreases the positiveness of its valence. McGraw-Hill, 1

reducing atmosphere

a. An atmosphere having a deficiency of oxygen.
b. An atmosphere of hydrogen or other substance that readily provides
electrons.
c. Space from which air has been displaced by hydrogen, carbon monoxide,
or other reducing gas. CTD

reducing flame

The blue part or inner cone of the flame produced by a blowpipe;
characterized by an excess of hydrocarbon over oxygen so as to reduce
mineral samples heated in it. See also:blowpiping
CF:oxidizing flame

reducing furnace

A furnace in which ores are reduced from oxides, or metal is separated
from other substances by a nonoxidizing heat or flame; usually a shaft
furnace. Syn:reduction furnace

reducing roast

The reduction of metallic oxides, sulfides, or halides by heating in
contact with carbon or other reducing agents. Newton, 1; Newton, 2

reduction

a. Process of reducing a metal compound to the metal and separating it
from the slag; sometimes applied to the smelting process.
b. A reaction taking place at the cathode in electrolysis through transfer
of electrons to the species being reduced.
c. A decrease in positive valence, or an increase in negative valence by
the gaining of electrons. A metallic oxide loses oxygen through the action
of reducing gas, reducing its valence. CF:oxidation

reduction cell

A pot or tank in which either a water solution of a salt or a fused salt
is reduced electrolytically to form free metals or other substances.
ASM, 1

reduction factor

The factor relating the allowable stress on a long column with that on a
short column in order to prevent buckling. Hammond

reduction furnace

See:reducing furnace.

reduction of area

a. The difference between the cross-sectional area of a tension specimen
at the section of rupture before loading and after rupture, expressed as a
percentage of the original area. Roark
b. Percentage decrease in cross-sectional area of bar or wire after
rolling or drawing. Hammond

reduction of levels

The calculation of reduced levels from the staff readings recorded in a
field book. Hammond

reduction ratio

In crushing, the ratio of the size of the largest feed particle to the
smallest distance between the roll faces. As used frequently in the field,
it is the ratio of the smallest aperture passing all of the feed to that
passing all of the product. Another basis of expression is the ratio of
the average size of feed to the average size of product.
See also:overall reduction ratio; primary breaker. Taggart, 1

reduction roasting

Lowering of oxygen content of ore by heating in reducing atmosphere.
Pryor, 3

reduction smelting

A pyrometallurgical process that produces an impure liquid metal and a
liquid slag by heating a mixture of ore, flux, and reducing agent (usually
coke). Newton, 1; Newton, 2

reduction to center

The offset of a side auxiliary telescope requires a correction to observed
horizontal angles, and the offset of a top auxiliary telescope requires a
correction to observed vertical angles. The process of computing the
correct angle from the observed angle is called reduction to center.
Urquhart

reduzate

A sediment formed in a strongly reducing environment; e.g., coal,
sedimentary sulfides, or sedimentary sulfur. AGI

red vitriol

See:bieberite; rose vitriol.