flume vs menstruum

flume

noun
  • An open channel or trough used to direct or divert liquids. 

  • A ravine or gorge, usually one with water running through. 

verb
  • To transport (logs of wood) by floating them along a water-filled channel or trough. 

menstruum

noun
  • Any liquid medium 

  • The menses; menstrual discharge. 

  • A solvent. 

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