brittleness vs unsadness

brittleness

noun
  • The state of being brittle; aptness to break; fragility. 

  • The property by virtue of which a material is fractured without appreciable deformation by the application of load. 

unsadness

noun
  • infirmity, unsteadiness, weakness 

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