rock candy vs water ice

rock candy

noun
  • A form of confectionery made by crystallizing sugar around a string. 

water ice

noun
  • A dessert made from crushed ice that has been sweetened and flavoured. 

  • Ice made of frozen water; water in a solid physical state, especially when distinguished from other frozen substances. Contrast liquid water, water vapor. 

How often have the words rock candy and water ice occurred in a corpus of books? (source: Google Ngram Viewer )