An instrument designed for the determination of the amount of nitrogen in a compound; especially †(a) (originally) an instrument devised by Andrew Ure (1778–1857) for the measurement of alkalis (including sodium and potassium nitrates) by neutralization with acid (obsolete); (b) (later) an apparatus of a type devised by Georg Lunge (1839–1923), incorporating a burette and a parallel glass tube, for the measurement of the nitric oxide evolved by reaction of nitrates with sulphuric acid in the presence of mercury (and also used to measure gases evolved in other reactions).