amalgamate vs vitrify

amalgamate

verb
  • To make an alloy of a metal and mercury. 

  • To combine (free groups) by identifying respective isomorphic subgroups. 

  • To merge, to combine, to blend, to join. 

adj
  • Coalesced; united; combined. 

vitrify

verb
  • To convert into glass or a glass-like substance by heat and fusion. 

  • To be converted into glass, especially through heat. 

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