Dictionary of Chemistry [6th Ed.]

with a wide range of structures.

Borosilicate glasses are particularly

important; the addition of boron to

the silicate network enables the glass

to be fused at lower temperatures

than pure silica and also extends the

plastic range of the glass. Thus such

glasses as Pyrex have a wider range

of applications than soda glasses (nar-

row plastic range, higher thermal ex-

pansion) or silica (much higher

melting point). Borosilicates are also

used in glazes and enamels and in

the production of glass wools.

Bosch process See haber process.

Bose–Einstein statisticsSee

quantum statistics.

bosonA particle or system that

obeys Bose–Einstein statistics (see

quantum statistics). Combining

quantum mechanics with special rel-

ativity theory gives a result that a

boson has to have an integer spin. A

*photon is an example of a boson.

bottled gasGas supplied under

pressure in metal cylinders. The term

includes pressurized gas (e.g. oxygen

and nitrogen cylinders) and gases

liqueÜed under pressure (e.g. liquid

butane for use as a fuel). Colour con-

ventions are used to identify the type

of gas or, in some cases, the speciÜc

gas. The colour indicating the con-

tents is that of the shoulder of the

cylinder at the top. The convention is

not international, and practice differs

in different countries. In the UK, the

convention is:

Yellow for toxic or corrosive gases

Red forÛammable gases

Light blue for oxidizing gases

Maroon for acetylene

Dark green for argon

Grey for carbon dioxide

Brown for helium

Blue for nitrous oxide

Black for nitrogen

White for oxygen

Bosch process 82

b

A

• Information on colour coding of gas
  containers

bound stateA system in which

two (or more) parts are bound to-

gether in such a way that energy is

required to split them. An example

of a bound state is a *molecule

formed from two (or more) *atoms.

bowspritSee ring conformations.

Boyle, Robert(1627–91) English

chemist and physicist, born in Ire-

land. After moving to Oxford in 1654

he worked on gases, using an air

pump made by Robert Hooke. In

1662 he discovered *Boyle’s law. In

chemistry he worked on *Ûame tests

and acid-base *indicators. Boyle is

generally regarded as the person who

established chemistry as a modern

subject, distinct from alchemy. He

was theÜrst to give a deÜnition of a

chemical element.

Boyle’s law The volume (V) of a

given mass of gas at a constant tem-

perature is inversely proportional to

its pressure (p), i.e. pV = constant.

This is true only for an *ideal gas.

This law was discovered in 1662 by

Robert *Boyle. On the continent of

Europe it is known as Mariotte’s law

after E. Mariotte (1620–84), who dis-

covered it independently in 1676. See

also gas laws.

Brackett seriesSee hydrogen

spectrum.

Bragg, Sir William Henry

(1862–1942) British physicist, who

with his son Sir William Lawrence

Bragg(1890–1971), was awarded the

1915 Nobel Prize for physics for their

pioneering work on X-ray crystallog-

raphy. He also constructed an X-ray

spectrometer for measuring the

wavelengths of X-rays. In the 1920s,

while director of the Royal Institu-