One litre of a sample of ozonized oxygen at 0C and 1 atm on passing through a Kl solution, liberated iodine which required 9 ml of a thiosulphate solution. A volume of 12 ml of a '5.675 volume' hydrogen peroxide solution liberated iodine from another iodide solution, which required 24 ml of the same thiosulphate solution. The volume percent of ozone in the ozonized oxygen sample is approximately Backspace 78 9