acerbate vs vitriol

acerbate

verb
  • To make bitter or sour. 

  • To exasperate; to irritate. 

adj
  • Embittered; having a sour disposition or nature. 

vitriol

verb
  • To subject to bitter verbal abuse. 

  • To dip in dilute sulphuric acid; to pickle. 

  • To vitriolize. 

noun
  • Bitterly abusive language. 

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