placate vs sadden

placate

verb
  • To calm; to bring peace to; to influence someone who was furious to the point that they become content or at least no longer irate. 

sadden

verb
  • To make sad or unhappy. 

  • To darken a color during dyeing. 

  • To become sad or unhappy. 

  • To render heavy or cohesive. 

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