system of units. Such a set requires
three mechanical units (usually of
length, mass, and time) and one elec-
trical unit; it has also been found
convenient to treat certain other
quantities as fundamental, even
though they are not strictly inde-
pendent. In the metric system the
centimetre–gram–second (c.g.s.)
system was replaced by the metre–
kilogram–second (m.k.s.) system; the
latter has now been adapted to pro-
vide the basis for *SI units. In British
Imperial units the foot–pound–
second (f.p.s.) system was formerly
used.
fungicideSee pesticide.
furanA colourless liquid com-
pound, C 4 H 4 O; r.d. 0.94; m.p. –86°C;
b.p. 31.4°C. It has aÜve-membered
ring consisting of four CH 2 groups
and one oxygen atom.
239 fusion
f
OFuran
furanose A *sugar having aÜve-
membered ring containing four car-
bon atoms and one oxygen atom.
furfural A colourless liquid,
C 5 H 4 O 2 , b.p. 162°C, which darkens
on standing in air. It is the aldehyde
derivative of *furan and occurs in
various essential oils and in *fusel
oil. It is used as a solvent for extract-
ing mineral oils and natural resins
and itself forms resins with some
aromatic compounds.fused ringSee ring.
A- Information about IUPAC nomenclature
fusel oilA mixture of high-
molecular weight *alcohols contain-
ing also esters and fatty acids, some-
times formed as a toxic impurity in
the distillation products of alcoholic
fermentation. It is used as a source of
higher alcohols and in making paints
and plastics.fusible alloysAlloys that melt at
low temperature (around 100°C).
They have a number of uses, includ-
ing constant-temperature baths, pipe
bending, and automatic sprinklers to
provide a spray of water to prevent
Üres from spreading. Fusible alloys
are usually *eutectic mixtures of bis-
muth, lead, tin, and cadmium.
*Wood’s metal, *Rose’s metal, and
Lipowitz’s alloy are examples of al-
loys that melt in the range 70–100°C.
fusionMelting.