DISCOVERY: A French astronomer, Pierre-Jules-César Janssen (1824-1907), first obtained evidence for the existence of helium during the solar eclipse of 1868 in India when he detected a new yellow line (587.49 nm) in the solar spectrum very close to the yellow sodium D-line. It was not possible to produce this line in the laboratory. Sir Norman Lockyer (1836-1920), an English astronomer, recognised that no known element at that time gave this line and named the element …showed first 75 words of 269 total…

…showed last 75 words of 269 total…as an inert gas shield for arc welding in countries where helium is cheaper than argon  protective gas in growing silicon and germanium crystals, and in titanium and zirconium production  cooling medium for nuclear reactors  a mixture of 80% helium and 20% oxygen is used as an artificial atmosphere for divers and others working under pressure  cryogenic applications as a gas for supersonic wind tunnels  a protective gas for semiconductor materials pressurizing liquid fuel rockets Bibliography none