perjure vs soft-soap

perjure

verb
  • To make a false oath to; to deceive by oaths and protestations. 

  • To cause to violate an oath or a vow; to cause to make oath knowingly to what is untrue; to make guilty of perjury; to forswear; to corrupt. 

  • To knowingly and willfully make a false statement of witness while in court. 

soft-soap

verb
  • To attempt to persuade by flattery or pleasing words; to butter up. 

noun
  • Persuasion by means of flattery or pleasing words. 

How often have the words perjure and soft-soap occurred in a corpus of books? (source: Google Ngram Viewer )