adulteration vs refinement

adulteration

noun
  • The action of adulterating, being mixed with extraneous material, illicit substitution of one substance for another. 

refinement

noun
  • The act, or the result of refining; the removal of impurities, or a purified material 

  • A fine or subtle distinction. 

  • High-class style; cultivation. 

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