elutriate vs expurgate

elutriate

verb
  • To decant; to purify something by straining it. 

  • To separate large and small particles through an upwardly flowing liquid or vapid stream. 

expurgate

verb
  • To undertake editing out incorrect, offensive, or otherwise undesirable information from (a book or other publication); to cleanse; to purge. 

  • To edit out (incorrect, offensive, or otherwise undesirable information) from a book or other publication; to cleanse; to purge. 

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