hollowness vs solidity

hollowness

noun
  • The state or quality of being hollow. 

solidity

noun
  • Moral firmness; validity; truth; certainty. 

  • The state or quality of being solid. 

  • The solid contents of a body; volume; amount of enclosed space. 

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