The Collaborative International Dictionary of English v.0.48:

Eudiometry \Eu`di*om"e*try\, n. [Cf. F. eudiom['e]trie.] (Chem.)
   The art or process of determining the constituents of a
   gaseous mixture by means of the eudiometer, or for
   ascertaining the purity of the air or the amount of oxygen in
   it.
   [1913 Webster]