“This name, which means `beautiful black,' was originally given to the Æthiop's mineral, or black sulphuret of mercury. It was afterwards applied in joke by Sir Theodore Mayerne to the chloride of mercury, in honour of a favourite negro servant whom he employed to prepare it. As calomel is a white powder, the name is merely a jocular misnomer.” —Medical Dictionary.
Greek, kaloz beautiful, melaz black.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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