Spanish green vs aerugo

Spanish green

noun
  • A pigment, formerly used in oil painting, obtained by exposing copper plates to vinegar (acetic acid). 

  • The color of copper after extended exposure to the atmosphere. 

aerugo

noun
  • metallic rust, particularly of brass or copper; verdigris 

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