Dictionary of Chemistry [6th Ed.]

the ability to supply 1 A for 1 hr, or

the equivalent.

bauxiteThe chief ore of alu-

minium, consisting of hydrous alu-

minium oxides and aluminous

laterite. It is a claylike amorphous

material formed by the weathering

of silicate rocks under tropical condi-

tions. The chief producers are Aus-

tralia, Guinea, Jamaica, Russia, Brazil,

and Surinam.

b.c.c.Body-centred cubic. See cubic

crystal.

beam balanceSee balance.

Beattie–Bridgman equationAn

*equation of state that relates the

pressure, volume, and temperature

of a gas and the gas constant. The

Beattie–Bridgman equation uses em-

pirical constants to take into account

the reduction in the effective num-

ber of molecules due to various types

of molecular aggregation. It is given

by

P = RT(1 – ε)(V + B)/V^2 – A/V^2 ,

where P is the pressure, T is the ther-

modynamic temperature, V is the

volume, R is the gas constant, and A,

B, and εare constants related toÜve

empirical constants A 0 , B 0 , a, b, and c

by: A = A 0 (1 – a/V), B = B 0 (1 – b/V), and

ε= c/VT^3.

Beckmann rearrangement The

chemical conversion of a ketone

*oxime into an *amide, usually using

sulphuric acid as a catalyst. The reac-

tion, used in the manufacture of

nylon and other polyamides, is

named after the German chemist

Ernst Beckmann (1853–1923).

Beckmann thermometerA ther-

mometer for measuring small

changes of temperature (see illustra-

tion). It consists of a mercury-in-glass

thermometer with a scale covering

only 5 or 6°C calibrated in hun-

dredths of a degree. It has two mer-

cury bulbs, the range of temperature

to be measured is varied by running

mercury from the upper bulb into

the larger lower bulb. It is used par-

ticularly for measuring *depression

of freezing point or *elevation of

boiling point of liquids when solute

is added, in order toÜnd relative mo-

lecular masses.

bauxite 60

b 5 4 3 2 1 0

reservoir for

adjusting range

scale for measuring

temperature change

stem

Beckmann thermometer

becquerel Symbol Bq. The SI unit

of activity (see radiation units). The

unit is named after the discoverer of

radioactivity A. H. *Becquerel.

Becquerel, Antoine Henri

(1852–1908) French physicist. His

early researches were in optics, then

in 1896 he accidentally discovered

*radioactivity inÛuorescent salts of

uranium. Three years later he

showed that it consists of charged

particles that are deÛected by a mag-

neticÜeld. For this work he was

awarded the 1903 Nobel Prize for

physics, which he shared with Pierre

and Marie *Curie.

Beer–Lambert lawA law relating