Compact unit to compare rates of absorption or evolution of gases by small organisms during respiration. Two stoppered boiling tubes are connected by three way taps at either end of a manometer. One tube holds the organisms and has a syringe for altering level of liquid in the manometer during setting up. The other tube acts as a control thermo – barometer
Features
Two stoppered tubes: One (the experimental tube) holds the living organisms (e.g., germinating seeds, insects) along with a chemical, such as potassium hydroxide (KOH) or soda-lime, to absorb the carbon dioxide they produce. The other (the control or thermo-barometer tube) is identical but contains an inert material, like glass beads, to match the volume of the organisms. A graduated manometer (often U-shaped): This connects the two tubes and contains a colored fluid. A syringe or a three-way tap: Used to adjust the initial fluid level in the manometer and to re-set the apparatus for measurements. A water bath (optional but recommended): The entire apparatus is often placed in a water bath to maintain a constant temperature, preventing gas volume fluctuations due to environmental changes.