ABSTRACT
The consumption or production of oxygen by biological systems can be measured by two alternative techniques based on quite different principles. The Warburg manometer, derived from the “blood-gas manometer” of Barcroft and Haldane, is a constant volume system in which gas evolution or uptake results in a pressure change; the physical parameters for each flask must be known before the necessary calculations can be made. The alternative is a constant pressure system, which has the distinct advantage that gas changes can be measured directly and flask calibration is not required. At its most sophisticated, in the Gilson differential respirometer, this provides direct readout by vernier scales fitted to individual flask and manometer units which are used to move volume compensating pistons. Generally speaking, capacities, procedures for setting up reaction vessels, levels of accuracy, and flexibility are similar whether the conventional Warburg apparatus or the Gilson constant pressure system is being used.
