pardoning vs purgation

pardoning

noun
  • The act by which somebody is pardoned. 

purgation

noun
  • The process or act of cleansing from sin or guilt. 

  • The process or act of purging, such as by the use of a purgative. 

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