quicksilver vs unchanging

quicksilver

verb
  • To overlay with quicksilver. 

  • To treat with quicksilver. 

noun
  • The metal mercury. 

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

adj
  • Unpredictable, erratic or fickle; mercurial. 

unchanging

adj
  • remaining constantly unchanged 

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