Sulphur is the processed product from natural sulphur ore, a nonmetallic chemical element belonging to the oxygen family, one of the most reactive of the elements.
Known to the ancients (in Genesis it is called brimstone), sulphur was first classified as an element in 1777 by Antoine Lavoisier. It is estimated to be the ninth most abundant element in the universe. In the form of sulphides, sulphates, and elemental sulphur, the element constitutes about 0.03 percent of the Earth's crust. After oxygen and silicon, it is the most abundant constituent of minerals.
Native or free sulphur occurs chiefly in volcanic or sedimentary deposits. The former are located throughout the world; the latter are especially common along the U.S. coastal region of Texas and Louisiana. Coal, petroleum, and natural gas contain sulphur compounds. Sulphur-containing ores include such sulphides as pyrite (iron disulphide), galena (lead sulphide), cinnabar (mercury sulphide), sphalerite (zinc sulphide), and chalcopyrite (copper iron sulphide), as well as such sulphates as gypsum (calcium sulphate) and barite or heavy spar (barium sulphate).
Where deposits of sulphur are located in salt domes, as they are along the coast of the Gulf of Mexico, the element is recovered by the Frasch process. This process has made sulphur of a high purity (up to 99.9 percent pure) available in large quantity and has helped establish sulphur as one of the four most important basic chemical commodities.
Pure sulphur is a tasteless, odorless, brittle solid that is pale yellow in colour, a poor conductor of electricity, and insoluble in water. The element exists in several different forms, the two most important being the orthorhombic (often called rhombic) and monoclinic crystalline modifications.
Rhombic sulphur, which is stable at room temperature, includes the common roll sulphur (or brimstone), flowers of sulphur (a finely divided form obtained by sublimation of vapor directly to a solid upon cooling), and much natural sulphur.
Monoclinic, or prismatic, sulphur, which is obtained when liquid sulphur is cooled slowly, consists of long, needlelike crystals. It is stable between 96¢X C and 119¢X C, but at room temperature it changes slowly to the rhombic form. When hot molten sulphur is cooled suddenly (as by pouring it into cold water), it forms a soft, sticky, elastic, noncrystalline mass called amorphous, or plastic, sulphur. Although the rhombic and monoclinic forms are highly soluble in carbon disulphide, amorphous sulphur is not.
In China, sulphur is produced mainly in Shanxi, Shandong and Henan provinces. For oral administration as a drug, it should be boiled in water with soybean curd (till gets dark green) and dried in the shade after removing the bean curd and grinded into powder when used.
Also spelled Sulfur. |
