crack cocaine vs freebase

crack cocaine

noun
  • A mixture of baking soda and cocaine in solid form that is smoked in a pipe as a narcotic. 

  • A mixture of salt substitute, ether, and cocaine in a semi-liquid form, which is far more potent than if made with baking soda alone. 

freebase

noun
  • The purified, dry form of certain illegal drugs, especially cocaine. 

  • The purified, dry form of an amine, especially an alkaloid natural product, that is normally used in solution. 

verb
  • To purify a drug by crystallization. 

  • To use a purified drug, especially cocaine, by heating it and inhaling the fumes produced. 

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