childish vs quicksilver

childish

adj
  • Immature in thought or behaviour. 

  • Of or suitable for a child. 

quicksilver

adj
  • Unpredictable, erratic or fickle; mercurial. 

noun
  • The metal mercury. 

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

verb
  • To overlay with quicksilver. 

  • To treat with quicksilver. 

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