gypsum vs smelt

gypsum

noun
  • A mineral consisting of hydrated calcium sulphate. When calcinated, it forms plaster of Paris. 

smelt

noun
  • Any of the various liquids or semi-molten solids produced and used during the course of such production. 

  • Any small anadromous fish of the family Osmeridae, found in the Atlantic and Pacific Oceans and in lakes in North America and northern part of Europe. 

  • Production of metal, especially iron, from ore in a process that involves melting and chemical reduction of metal compounds into purified metal. 

verb
  • To fuse or melt two things into one, especially in order to extract metal from ore; to meld. 

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