quicksilver vs unchangeable

quicksilver

verb
  • To overlay with quicksilver. 

  • To treat with quicksilver. 

adj
  • Unpredictable, erratic or fickle; mercurial. 

noun
  • The metal mercury. 

  • An amalgam of mercury and tin applied to the backs of mirrors, quicksilvering. 

unchangeable

noun
  • Something that cannot be changed. 

adj
  • Not changeable; incapable of being changed or of changing; immutable. 

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