liquid gold vs petrol

liquid gold

noun
  • Crude oil. 

  • Water. 

  • Beer. 

  • Urine. 

  • Sandalwood oil 

  • A kind of liquid preparation used to decorate ceramic ware with gold or gold colour. 

  • Any liquid that is yellow in color, such as beer, olive oil or a liquid cheese. 

  • Colostrum. 

petrol

noun
  • petroleum, a fluid consisting of a mixture of refined petroleum hydrocarbons, primarily consisting of octane, commonly used as a motor fuel. 

  • A motor vehicle powered by petrol (as opposed to diesel). 

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