Definition of calx in US English:


nounPlural calces

  • A powdery metallic oxide formed when an ore or mineral has been heated.

    • ‘Then a French pharmacist named Pierre Bayen pointed out to Lavoisier that calx of mercury, which we would now call mercuric oxide, can be converted to mercury simply by heating.’
    • ‘Boyle knew the tin gained weight as the calx was formed.’
    • ‘The calx combines with a flux containing phlogiston-rich materials.’
    • ‘Other common names by which the compound is known include burnt lime, unslaked lime, fluxing lime, and calx.’
    • ‘The reason a metal formed when its calx was heated with charcoal was therefore because the phlogiston left the charcoal and united with the calx.’


Late Middle English: from Latin, ‘lime’, probably from Greek khalix ‘pebble, limestone’.