scoria vs treddle

scoria

noun
  • The slag or dross that remains after the smelting of metal from an ore. 

  • Rough masses of rock formed by solidified lava, and which can be found around a volcano's crater. 

treddle

noun
  • The dung of sheep or hares. 

  • A prostitute; strumpet. 

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