go bad vs purify

go bad

verb
  • Of foods and commodities, to spoil, rot, or otherwise become unusable due to age or storage conditions. 

  • Of a person or entity, to cease to be reputable and instead become delinquent, criminal, immoral, corrupt or poorly behaved. 

  • Of a geographic area, to become unsafe. 

purify

verb
  • To cleanse, or rid of impurities. 

  • To become pure. 

  • To free from guilt or sin. 

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