heating vs smelting

heating

noun
  • The act of making something hot. 

  • A system that raises the temperature of a room or building. Compare heater. 

adj
  • Causing heat. 

smelting

noun
  • The process of melting or fusion, especially to extract a metal from its ore. 

How often have the words heating and smelting occurred in a corpus of books? (source: Google Ngram Viewer )