Reduction can occur in the range of
temperatures in which the carbon
curve is lower than the metal curve.
The diagram was devised by the
physical chemist H. J. T. Ellingham.
elliptical polarization See polar-
ization of light.
elongation (in protein synthesis)
The phase in which amino acids are
linked together by sequentially
formed peptide bonds to form a
polypeptide chain. Elongation factors
are proteins that – by binding to a
tRNA–amino-acid complex – enable
the correct positioning of this com-
plex on the ribosome, so that transla-
tion can proceed.
eluateSee chromatography; elu-
tion.
eluent See chromatography; elu-
tion.
elutionThe process of removing an
adsorbed material (adsorbate) from
an adsorbent by washing it in a liq-
uid (eluent). The solution consisting
of the adsorbate dissolved in the elu-
ent is the eluate. Elution is the
process used to wash components of
a mixture through a *chromatogra-
phy column.
elutriation The process of suspend-
ingÜnely divided particles in an up-
wardÛowing stream of air or water
to wash and separate them into sized
fractions.
emanationThe former name for
the gas radon, of which there are
three isotopes: Rn–222 (radium ema-
nation), Rn–220 (thoron emanation),
and Rn–219 (actinium emanation).
emerald The green gem variety of
*beryl: one of the most highly prized
gemstones. TheÜnest specimens
occur in the Muzo mines, Colombia.
Other occurrences include the Ural
Mountains, the Transvaal in South
Africa, and Kaligunan in India. Emer-
alds can also be successfully synthe-
sized.emergency action codeSee
hazchem code.emeryA rock composed of corun-
dum (natural aluminium oxide,
Al 2 O 3 ) with magnetite, haematite, or
spinel. It occurs on the island of
Naxos (Greece) and in Turkey. Emery
is used as an abrasive and polishing
material and in the manufacture of
certain concreteÛoors.e.m.f.See electromotive force.emission spectrumSee spectrum.empiricalDenoting a result that is
obtained by experiment or observa-
tion rather than from theory.empirical formulaSee formula.emulsiÜcation (in digestion) The
breakdown of fat globules in the duo-
denum into tiny droplets, which pro-
vides a larger surface area on which
the enzyme pancreatic *lipase can
act to digest the fats into fatty acids
and glycerol. EmulsiÜcation is as-
sisted by the action of the bile salts
in bile.emulsionA *colloid in which small
particles of one liquid are dispersed
in another liquid. Usually emulsions
involve a dispersion of water in an
oil or a dispersion of oil in water, and
are stabilized by an emulsiÜer. Com-
monly emulsiÜers are substances,
such as *detergents, that have
lyophobic and lyophilic parts in their
molecules.enThe symbol for ethylene diamine
(1,2-diaminoethane) functioning as a
bidentate ligand, used in formulae.enamineA type of compound with
the general formula
R^1 R^2 C = C(R^3 )–NR^4 R^5 ,203 enamine
e