Disulfur decafluoride (S2F10) is a gas discovered in 1934 by Denbigh and Whytlaw-Gray. Each S of the S2F10 molecule is octahedral, and surrounded by 5 fluorines. S2F10 is highly toxic, with toxicity 4 times that of phosgene. It was considered a potential chemical warfare pulmonary agent in World War II because it does not produce lacrimation or skin irritation, thus providing little warning of exposure. It is produced by the electrical decomposition of sulfur hexafluoride (SF6)—an essentially inert insulator used in high voltage systems such as transmission lines, substations and switchgear. S2F10 is also made during the production of SF6, but is distilled out.