clarification vs emendation

clarification

noun
  • The act of freeing from obscurities. 

  • The act of clarifying; the act or process of making clear or transparent by freeing visible impurities; particularly, the clearing or fining of liquid substances from feculent matter by the separation of the insoluble particles which prevent the liquid from being transparent. 

emendation

noun
  • The act of altering for the better, or correcting what is erroneous or faulty; correction; improvement. 

  • An intentional change in the spelling of a scientific name, which is usually not allowed. 

  • Alteration by editorial criticism, as of a text so as to give a better reading; removal of errors or corruptions from a document. 

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