sulphur

Two common allotropes of sulphur: rhombic and monoclinic crystals. A reactive element, sulphur combines with most other elements and has a wide range of industrial uses. It often occurs around hot springs and in volcanic regions, and there are large deposits in the USA (Texas and Louisiana), Japan, Sicily, and Mexico.

Brittle, pale-yellow, non-metallic element, atomic number 16, relative atomic mass 32.064. It occurs in three allotropic forms: two crystalline (called rhombic and monoclinic, following the arrangements of the atoms within the crystals) and one amorphous. It burns in air with a blue flame and a stifling odour. Insoluble in water but soluble in carbon disulphide, it is a good electrical insulator. Sulphur is widely used in the manufacture of sulphuric acid (used to treat phosphate rock to make fertilizers) and in making paper, matches, gunpowder and fireworks, in vulcanizing rubber, and in medicines and insecticides.

It is found abundantly in nature in volcanic regions combined with both metals and non-metals, and also in its elemental form as a crystalline solid. It is a minor constituent of proteins. It has been known since ancient times and was called sulphur, later sulfur, in Latin.

Between 20 and 50 million tonnes of sulfur are returned from the oceans to the atmosphere every year in the form of dimethyl sulfide (DMS), the gas that gives sea air its bracing smell. DMS is a breakdown product of a salt produced by marine algae to maintain their osmotic balance (see osmosis). Human activity releases about 80 million tonnes of sulfur.

Sulphur

City in southwestern Louisiana, 16 km/10 mi west of Lake Charles; population (1990) 20,100. It is in an oil and livestock producing area. Oil was discovered nearby in 1924. The large sulphur dome in the city was worked from 1905 to 1926.