amassment vs dispersal

amassment

noun
  • That which is amassed; a large quantity (of something). 

  • The act of amassing. 

dispersal

noun
  • The act or result of dispersing or scattering; dispersion. 

  • A dispersal prison. 

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