bathtub gin vs firewater

bathtub gin

noun
  • Gin or a similar alcoholic beverage which is of very poor quality, as if made by a homebrewer in a bathtub. 

firewater

noun
  • High-proof alcohol, especially whiskey (especially in the context of its sale to or consumption by Native Americans). 

  • High-temperature hydraulic condensate discharged from industrial boilers. 

  • Water for use in firefighting. 

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