After Haldane's method of sampling the alveolar air we took one sharp and forced expiration through a piece of hose-pipe about 105cm long and 2.5cm in diameter, after 2, 5, 10, 15 and 30 times forced breathings each of which was done once per 2 seconds. Then, at once, the last part of this expired air was collected into a vacuous sampling tube introduced air-tight through a hole at the wall of the hose-pipe near the mouth piece, and analysed by means of Haldane's gas analysis apparatus. Conclusion: 1) The CO(2)-pressure in normal resting alveolar air, taken by the original method in a sitting position is 40.4mm-43.5mm of Hg, and the O(2)-pressure in it is 96.5mm-108.2mm of Hg. 2) After 2 times forced breathings, the CO(2)-pressure in alveolar air is remarkably diminished, that is, to 27.1mm-28.7mm of Hg, and the O(2)-pressure raised to 128.7mm-131.0mm of Hg.
More than these 2 times forced breathings did not cause a noticeable change on the CO(2)- and O(2)-pressures in alveolar air.