solidify vs unify

solidify

verb
  • To concentrate; consolidate. 

  • To make solid; convert into a solid body. 

  • To become solid; to freeze, set. 

unify

verb
  • Cause to become one; make into a unit; consolidate; merge; combine. 

  • Become one. 

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