alchemy vs black art

alchemy

noun
  • Any elaborate transformation process or algorithm. 

  • The causing of any sort of mysterious sudden transmutation. 

  • The premodern and early modern study of physical changes, particularly in Europe, Arabia, and China and chiefly in pursuit of an elixir of immortality, a universal panacea, and/or a philosopher's stone able to transmute base metals into gold, eventually developing into chemistry. 

black art

noun
  • A process that is mysterious or difficult to master. 

  • A practice such as witchcraft, sorcery, necromancy, or black magic. 

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