lye vs sodium

lye

noun
  • Potassium or sodium hydroxide (caustic soda). 

  • An alkaline liquid made by leaching ashes (usually wood ashes). 

  • A short side line, connected with the main line; a turn-out; a siding. 

verb
  • To treat with lye. 

sodium

noun
  • Employing sodium. 

  • The chemical element (symbol Na) with an atomic number of 11 and atomic weight of 22.990. It is a soft, waxy, silvery, reactive alkali metal that is never found unbound in nature. 

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