The History of Chlorine
Chlorine was discovered by Karl Wilhelm Scheele, a Swedish chemist, in 1774. Scheele thought that chlorine was an oxide of murium, or hydrochloric acid. Scheele heated manganese dioxide and hydrochloric acid and discovered this greenish, yellow gas. He did not, however, establish chlorine as an element. In 1810, chlorine was named and classified as an element by Humphrey Davy. It was named after the Greek word chloros, which means pale green.
Chlorine has also been used during World War I. It was first introduced as a weapon on April 22, 1915 at Ypres by the Germans. The results of this weapon were disastrous because gas makes had not yet been invented. But, some compounds of chlorine are more dangerous and have replaced chlorine gas on the battle field. They are phosgene, chloropicrin, Lewsite, and mustard gas.