Douglas McDonald, age 13, of Baton Rouge, La., for his question:
WHERE IS SULFUR FOUND?
Sulfur is a solid, nonmetallic element. It is found in many vegetables, such as onions, cabbage and horseradish. Eggs also contain sulfur. In the mineral world, sulfur is found in large quantities both in a pure state and in combination with other substances.
Sulfur occurs in a pure state in places where there are volcanoes. It combines with metals to form certain valuable metal ores wuch as sphalerite, galena, cinnabar and stibnite. Gypsum, or calcium sulfate, is an important mineral that contains sulfur.
Before 1900 almost all sulfur came from Sicily. Today the United States produces much sulfur, chiefly in Louisiana and Texas. Sulfur is also found in Spain, Mexico, Japan and Italy.
Sulfur has many commercial uses. For the farm, sulfur is used in the manufacturer of fertilizers and in preparations that destroy insects and plant pests. Sulfur is also used in making paper pulp. It is also used in various medicines and is considered helpful in certain skin diseases. Also, photographers use a sulfur compound, sodium thiosulfate, to fix photographic images after development.
The most common method of mining sulfur is called the superheated water method. This method was invented about 1900 by an American scientists named Herman Frasch. By this method, sulfur deposits are heated beyond the melting point, known as superheating.
Water is superheated under increased pressure so that its boiling point rises above surfur's melting point. Four pipes, one inside the other, bore into the sulfur deposit.
The two outside pipes force the hot water into the sulfur, causing the sulfur to melt. The fourth and innermost pipe sends down compressed air into the deposit. This causes the melted sulfur to form a froth. The increased air pressure forces the froth up the third pipe.
All other substances that have a higher melting point remain.
Sulfur of about 99 percent purity is obtained with the superheated water method. The frothy sulfur is sprayed into bins after it reaches the surface and it is then allowed to dry thoroughly in the open air.
By another and newer method, the sulfur cools and solidifies on a conveyor belt moving over shallow tanks of cold, running water.
Sulfur may be recovered in acid form from gases at metallic sulfide smelters. Sulfur as an element may be obtained from some natural gases and from refinery gas. ,
Sulfur is brittle and has almost no taste. When it is rubbed or melted, it gives off a "rotten egg" odor. It does not dissolve in water but it dissolves readily in carbon disulfide.
Sulfur ignites at a low temperature and burns very quickly. It burns in air with a pale blue flame and gives off sulfur dioxide, a colorless gas. When sulfur dioxide is exposed to moist air, it mixes with the moisture in the air and forms sulfuric acid. Both sulfur dioxide and sulfuric acid are constantly being formed in the air in cities that burn a large amount of coal and gas.