barm vs spurge

barm

verb
  • To spurge; foam 

noun
  • A small, flat, round individual loaf or roll of bread. 

  • Foam rising upon beer, or other malt liquors, when fermenting, and used as leaven in making bread and in brewing; yeast. 

spurge

verb
  • To emit foam; to froth; said of the emission of yeast from beer during fermentation. 

noun
  • Any plant of the genus Euphorbia, a diverse genus of over 2,000 species. 

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