gasometer

noun2

1. •
   A large tank or reservoir for storing gas; a gasholder.

   • The attack on the gasworks was probably the most risky, as none of the rebels had any idea of just what kind of blast an exploding gasometer might produce […] — 1977
2. •
   An apparatus used to store or measure gas or the flow of gas, particularly in a laboratory setting.

   • The collected air was metered through a gasometer, and the composition of every gas sample was analyzed in duplicate […] — 2012