Abstract Methods for rapid determination of oxygen consumption among young chickens have been described by Strite and Yacowitz (1956) and by Charkey and Thornton (1959). Both methods use gas burettes, leveling bottles and CO2 absorbents to measure consumption of oxygen. Strite and Yacowitz (1956) measured the amount of oxygen used in 10 minutes, with an inverted beaker for a chamber. Charkey and Thornton (1959) read the amount of oxygen used in 3 minutes, with a dessicator for a chamber. Repeated observations were made until successive readings checked. The apparatus shown in Fig. 1 and procedure described here have evolved from the use of chambers and methods noted above. The chamber is built around a 9.46 liter cooking pot with a lid having a vertical lip. A moat is constructed on the pot so that the lid will drop into a fluid seal. The original chamber held an aluminum strip with “pop” . . .