temperatures at standard pressure of
ice in equilibrium with water (0°C)
and water in equilibrium with steam
(100°C). The scale, between these two
temperatures, is divided in 100 degrees. The degree Celsius (°C) is equal
in magnitude to the *kelvin. This
scale was formerly known as the
centigrade scale; the name was ofÜcially changed in 1948 to avoid confusion with a hundredth part of a
grade. It is named after the Swedish
astronomer Anders Celsius (1701–44),
who devised the inverted form of
this scale (ice point 100°, steam point
0°) in 1742.
cement Any of various substances
used for bonding or setting to a hard
material. Portland cement is a mixture of calcium silicates and aluminates made by heating limestone
(CaCO 3 ) with clay (containing aluminosilicates) in a kiln. The product is
ground to a Üne powder. When
mixed with water it sets in a few
hours and then hardens over a
longer period of time due to the formation of hydrated aluminates and
silicates.
cementation Any metallurgical
process in which the surface of a
metal is impregnated by some other
substance, especially an obsolete
process for making steel by heating
bars of wrought iron to red heat for
several days in a bed of charcoal. See
also case hardening.
cementite See steel.
centi- Symbol c. A preÜx used in
the metric system to denote one hundredth. For example, 0.01 metre = 1
centimetre (cm).
centigrade scale See celsius
scale.
centrifugal pump See pump.
centrifuge A device in which solid
or liquid particles of different densities are separated by rotating them in
a tube in a horizontal circle. The
denser particles tend to move along
the length of the tube to a greater radius of rotation, displacing the
lighter particles to the other end.
ceramics Inorganic materials, such
as pottery, enamels, and refractories.
Ceramics are metal silicates, oxides,
nitrides, etc.
cerebroside Any one of a class of
*glycolipids in which a single sugar
unit is bound to a sphingolipid (see
phospholipid). The most common
cerebrosides are galactocerebrosides,
containing the sugar group galactose;
they are found in the plasma membranes of neural tissue and are abundant in the myelin sheaths of
neurones.
cerium Symbol Ce. A silvery metallic element belonging to the *lanthanoids; a.n. 58; r.a.m. 140.12; r.d.
6.77 (20°C); m.p. 799°C; b.p. 3426°C.
It occurs in allanite, bastnasite,
cerite, and monazite. Four isotopes
occur naturally: cerium–136, –138,
–140, and –142; Üfteen radioisotopes
have been identiÜed. Cerium is used
in mischmetal, a rare-earth metal
containing 25% cerium, for use in
lighter Ûints. The oxide is used in
the glass industry. It was discovered
by Martin Klaproth (1743–1817) in
1803.
A
• Information from the WebElements site
cermet A composite material consisting of a ceramic in combination
with a sintered metal, used when a
high resistance to temperature, corrosion, and abrasion is needed.
cerussite An ore of lead consisting
of lead carbonate, PbCO 3 . It is usually
of secondary origin, formed by the
weathering of *galena. Pure cerussite
is white but the mineral may be grey
111
cerussite
c
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ice in equilibrium with water (0°C)
and water in equilibrium with steam
(100°C). The scale, between these two
temperatures, is divided in 100 degrees. The degree Celsius (°C) is equal
in magnitude to the *kelvin. This
scale was formerly known as the
centigrade scale; the name was ofÜcially changed in 1948 to avoid confusion with a hundredth part of a
grade. It is named after the Swedish
astronomer Anders Celsius (1701–44),
who devised the inverted form of
this scale (ice point 100°, steam point
0°) in 1742.
cement Any of various substances
used for bonding or setting to a hard
material. Portland cement is a mixture of calcium silicates and aluminates made by heating limestone
(CaCO 3 ) with clay (containing aluminosilicates) in a kiln. The product is
ground to a Üne powder. When
mixed with water it sets in a few
hours and then hardens over a
longer period of time due to the formation of hydrated aluminates and
silicates.
cementation Any metallurgical
process in which the surface of a
metal is impregnated by some other
substance, especially an obsolete
process for making steel by heating
bars of wrought iron to red heat for
several days in a bed of charcoal. See
also case hardening.
cementite See steel.
centi- Symbol c. A preÜx used in
the metric system to denote one hundredth. For example, 0.01 metre = 1
centimetre (cm).
centigrade scale See celsius
scale.
centrifugal pump See pump.
centrifuge A device in which solid
or liquid particles of different densities are separated by rotating them in
a tube in a horizontal circle. The
denser particles tend to move along
the length of the tube to a greater radius of rotation, displacing the
lighter particles to the other end.
ceramics Inorganic materials, such
as pottery, enamels, and refractories.
Ceramics are metal silicates, oxides,
nitrides, etc.
cerebroside Any one of a class of
*glycolipids in which a single sugar
unit is bound to a sphingolipid (see
phospholipid). The most common
cerebrosides are galactocerebrosides,
containing the sugar group galactose;
they are found in the plasma membranes of neural tissue and are abundant in the myelin sheaths of
neurones.
cerium Symbol Ce. A silvery metallic element belonging to the *lanthanoids; a.n. 58; r.a.m. 140.12; r.d.
6.77 (20°C); m.p. 799°C; b.p. 3426°C.
It occurs in allanite, bastnasite,
cerite, and monazite. Four isotopes
occur naturally: cerium–136, –138,
–140, and –142; Üfteen radioisotopes
have been identiÜed. Cerium is used
in mischmetal, a rare-earth metal
containing 25% cerium, for use in
lighter Ûints. The oxide is used in
the glass industry. It was discovered
by Martin Klaproth (1743–1817) in
1803.
A
• Information from the WebElements site
cermet A composite material consisting of a ceramic in combination
with a sintered metal, used when a
high resistance to temperature, corrosion, and abrasion is needed.
cerussite An ore of lead consisting
of lead carbonate, PbCO 3 . It is usually
of secondary origin, formed by the
weathering of *galena. Pure cerussite
is white but the mineral may be grey
111
cerussite
c
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