| http://www.w3.org/ns/prov#value | - Its boiling and melting points are the lowest among the elements and it exists only as a gas except in extreme conditions.An unknown yellow spectral line signature in light was first observed from a solar eclipse in 1868 by French astronomer Pierre Janssen who is jointly credited with the discovery of the element with Norman Lockyer who observed the same eclipse and was the first to propose this w
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