Calx

[S]ome ladies apply to what are termed coſmetics under various names, which crowd the newspapers. Of theſe the white has deſtroyed the health of thouſands; a calx, or magiſtery, of biſmuth is ſuppoſed to be ſold in the ſhops for this purpoſe; but it is either, I am informed, in part or entirely white lead or ceruffa. […] The real calx of biſmuth would probably have the ſame ill effect.

Source: wiktionary

The regeneration of mercury from its calx, without addition of any other substance, had been a chief example for anti-phlogiston, but that could, as Kirwan showed, be explained in a way consistent with phlogiston theory.

Source: wiktionary