1. the powdery residue left after a metal or mineral has been heated or burned
Usage: chemistry; archaic
2. lime or calcium oxide
Usage: chemistry; technical

Examples

• The alchemist collected the calx remaining after heating the metal.
• Ancient metallurgists studied the calx produced during smelting.
• The calx of iron was used in early chemical experiments.
• Heating limestone produces calx, which was valuable for construction.
• The chemist analyzed the white calx left in the crucible.
• Medieval scholars wrote about the properties of various calx compounds.