The K O H solution is washed into a 11. flask and made up to volume. Aliquots(10 ml.) are analysed gravimetrically for carbonate, hence C0 2 production can be determined accurately. The difference between the weight of the cylinder at the start and finish of the experiment gives O2 consumption. A top-loading balance(Mettler-Ps)1 is used to weigh the cylinder to the nearest 100 mg. by interpolation,or with an error of about 100 ml. in a 24 hr. measurement period.