combustion vs stewing

combustion

noun
  • The act or process of burning. 

  • A process wherein a fuel is combined with oxygen, usually at high temperature, releasing heat. 

  • A process whereby two chemicals are combined to produce heat. 

  • Violent agitation, tumult. 

stewing

noun
  • The act by which something is stewed. 

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