The Collaborative International Dictionary
Mercurialist
Mercurialist \Mer*cu"ri*al*ist\, n.
One under the influence of Mercury; one resembling Mercury in character.
(Med.) A physician who uses much mercury, in any of its forms, in his practice.
Wiktionary
mercurialist
n. (context archaic medicine English) A doctor who uses mercury or supports its use in medicine.