The Collaborative International Dictionary
Volumescope
Volumescope \Vo*lu"me*scope\, n. [Volume + -scope.] (Physics) An instrument consisting essentially of a glass tube provided with a graduated scale, for exhibiting to the eye the changes of volume of a gas or gaseous mixture resulting from chemical action, etc.
Wiktionary
volumescope
n. An instrument consisting of a glass tube with a graduated scale that shows the changes in volume of a gas or gaseous mixture.