Figure 1 - Device for the measurement of oxygen evolution. The reaction test tube (RT) is held by a support (ST), connected to the stirrer motor (M) through a steel bar (B). RT is connected to the manometer (MA) by a rubber tubing (T). The bulb of the manometer is provided with a valve (V) to equilibrate the system with the atmospheric pressure before mixing the reagents. RT total capacity is 12.0 ml.