hg is the chemical symbol of murcurie.
murcurie was the messanger of greek gods.
probably none of which has anything to do with a girl flying around with fluffy wings and a number zero floating around her head.

nor i suppose, with mercurie rising in a glass tube to indicate a rise in temperature.

existence is of course not confined to our physical world
neither is the non-physical confined to what or how we choose to perceive.