demountable vs erasable

demountable

adj
  • Able to be removed from its mount; designed to be dismantled. 

noun
  • A temporary and portable building, especially a portable classroom in a school. 

erasable

adj
  • Capable of being erased 

noun
  • Any recording medium whose contents can be erased. 

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