Good quantitative results can be achieved using the Osborne Electrolysis Apparatus. Two graduated 20 mL tubes (with scales graduated in 0.2 mL divisions) slide up and down within the side arms of an H tube. Gases can be retained or released using the screw clamps attached to the rubber tubing at the top of each tube. A glass reservoir tube and platinum electrodes complete the unit. Overall height is 173.4". With instructions.