mescalin vs mescaline

mescalin

mescaline

noun
  • A hallucinogenic and intoxicating compound present in the peyote cactus (Lophophora williamsii), the San Pedro cactus (Echinopsis pachanoi), and the Peruvian torch (Echinopsis peruviana). 

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