adulterate vs expiate

adulterate

verb
  • To corrupt, to debase (someone or something). 

  • To make less valuable or spoil (something) by adding impurities or other substances. 

expiate

verb
  • To make amends or pay the penalty for. 

  • To wind up, bring to an end. 

  • To purify with sacred rites. 

  • To atone or make reparation for. 

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