.INTRODUCTION ABOUT SULPHUR.

Sulphur has been known for its medicine value and it's germicidal effect since 1000 B.C. However, it's chemical nature remained unknown until 1787 when Lavoisier recognized it as an element.

Sulphur makes up about 0.1% of the Earth's crust.
It occurs freely as deposits in u.s.a. , Poland, Japan, new Zealand and Sicily. It is also widely found in the combined state as sulphides of iron, zinc, lead, copper and mercury, and as the tetraoxosulphate (vi) salts of calcium, magnesium and barium. Sulphur is also present in some proteins.

ALLOTROPES OF SULPHUR.

The main allotropes of sulphur are rhombic sulphur (a_ sulphur ) and monoclinic or prismatic sulphur.( B_ sulphur), which are crystalline, and amorphous sulphur (s_ sulphur ) . There is also another form known as plastic sulphur.

1. RHOMBIC SULPHUR _ Free sulphur exists as rhombic sulphur in nature because it is the only stable allotrope at temperatures below 96 .C. crystals of rhombic sulphur are bright yellow and octahedral. They are made up of S8 molecules. Each S8 molecules consists of a ring of eight atoms.

2. AMORPHOUS SULPHUR. Amorphous sulphur has no regular crystalline shape. It is prepared as a pale yellow, almost white deposit when hydrogen sulphide is bubbled through water for a long time and the saturated solution is exposed to air. It is also deposited in chemical reactions, e.g. by the action of dilute hydrochloric acid on a trioxothiosulphate (vi) solution.