acerbate vs spit feathers

acerbate

verb
  • To make bitter or sour. 

  • To exasperate; to irritate. 

adj
  • Embittered; having a sour disposition or nature. 

spit feathers

verb
  • To feel very angry; to sputter angrily. 

  • To feel very thirsty. 

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