admix vs catchment

admix

verb
  • To mingle with something else; to mix. 

noun
  • The mixture that results from admixing, especially an alloy. 

  • The act of admixing. 

catchment

verb
  • To divide into catchment areas. 

noun
  • Any structure or land feature which catches and holds water; the collection of such water. 

  • A catchment area, or the people it serves. 

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