vial vs watch glass

vial

noun
  • A glass vessel or bottle, especially a small tube-shaped bottle used to store medicine, perfume or other chemicals. 

verb
  • To put or keep in, or as in, a vial. 

watch glass

noun
  • An item of glass laboratory equipment consisting of a simple, slightly concave circle of glass. It is a general utility item, used to hold small samples, to evaporate liquids, to cover a beaker, and so on. 

  • A sandglass. 

  • The glass covering of the face of a watch. 

How often have the words vial and watch glass occurred in a corpus of books? (source: Google Ngram Viewer )