effluvium vs fossil fuel

effluvium

noun
  • A gaseous or vaporous emission, especially a foul-smelling one. 

  • A condition causing the shedding of hair. 

fossil fuel

noun
  • Any fuel derived from hydrocarbon deposits such as coal, petroleum, natural gas and, to some extent, peat; these fuels are non-renewable, and their burning moves carbon from underground into the atmosphere via the greenhouse gas carbon dioxide. 

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