Büchner flask vs Dewar

Büchner flask

noun
  • A type of glass flask used in a laboratory similar to an Erlenmeyer flask, but with a side spout used for connection to an aspirator. 

Dewar

noun
  • A glass or metal double-walled flask for holding a liquid without much loss or gain of heat; a vacuum bottle or thermos. Generally used for scientific purposes and in particular for cryogenic work. 

name
  • A surname from Scottish Gaelic. 

  • An unincorporated community in Black Hawk County, Iowa, United States. 

  • A city in Okmulgee County, Oklahoma, United States. 

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