Sulphur, Chlorine and Iodine

Sulphur
You hear of copper, gold, silver and iron through out the Bible, but sulphur is mentioned more then once. Sluphur is translated to brimstone and no matter when it is mentioned it is always accompanied by punishment, destruction or threat of violence. In Genesis, the cities of Sodom and Gomorrah are over thrown when "brimstone and fire from the Lord out of heaven" comes upon them. No matter where sulphur is a bad connotation follows whether it is from stories or from it rotting egg sent. Sulphur was used ,though, to combat cholera into the 20th century.
Chlorine
Chlorine is best known for its use in warfare, which began in 1915. Chlorine is twice as heavy as air making it the best option for trench warfare, because it would settle in the trenches, leaving the enemy no choice; retreat or die. When chlorine is breathed in it rips through the blood vessels in the lungs and to try to mitigate the damage the body produces mucus, which eventually becomes so much that the person drowns. This was not the only time chlorine was used for war though, "Agent Orange" is a chlorofluorocarbon. This herbicide was used during the Vietnam War to try and thin the jungle to give the enemy less places to hide. Another herbicide, DDT, is well known too; it is a chlorinated hydrocarbon. After WWI there was a epidemic of the flu, which chlorine was used to help cure it; the irony in this is that it did not help a bit, but was used religiously.
Iodine
Iodine is said to be one of the great accidental discoveries of science. It is actually found I seawater and other mineral sources and used to treat goiter. The concentration of iodide in seawater is less the 100 ppb, but in seaweed its concentration can be the upwards of 3 thousand ppm. Iodine is an effective disinfectant, but produces quite a sting.