Heliencephalitis

What is Heliencephalitis?

Heliencephalitis definition and meaning on Dictionary terms:
noun
an inert, gaseous element present in the sun’s atmosphere and in natural gas, and also occurring as a radioactive decomposition product, used as a substitute for flammable gases in dirigible balloons. Symbol: He; atomic weight: 4.0026; atomic number: 2; density: 0.1785 g/l at 0

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