The three flasks after having been filled as described were attached to the apparatus and then all submerged to the same depth in the boiling water of a single glass water-bath. The stop-cocks of the azotometers were then opened and the mercury allowed to fall to within about fifty millimetres of its level in the reservoirs. This difference in level was maintained as nearly as practicable by lowering the reservoirs commenserably with the increase in gas volume. No action could be observed in flasks No. I and No. II during the whole course of the experiment. The contents of flask No. III however gave off bubbles of oxygen immediately, the mercury fell in the azotometer and the dark purple of the permanganate solution in flask No. III became rapidly lighter. Within about five minutes it was reduced to a delicate pink but this tint persisted for about ten minutes when it also disappeared. Immediately after the disappearance of the permanganate color the solution was filled with a brown oxide which remained for about thirty five minutes when it subsided leaving the supernatant liquid clear. Notwithstanding the fact that the color of the permanganate had entirely disappeared and the suspended oxide had subsided within an hour after beginning the experiment, the flasks in the earlier experiments were allowed to remain for two hours longer. By admitting distilled water through the tube =D= [see figure] the gas was then forced over into the azotometer. Finally, the oxygen was determined in the manner previously described. The following illustration from the first experiment may serve to show the method of calculating the results. I II III Total air and oxygen = 42.60 c.c. 52.40 c.c. 60.60 c.c. Nitrogen after absorption of oxygen = 34.00 c.c. 40.90 c.c. 37.80 c.c. Oxygen = 8.60 c.c. 11.50 c.c. 22.80 c.c. Air = 79.8% nitrogen 20.2% oxygen Oxygen of air 20.2 -------------- × ---- = 8.60 c.c. 10.353 c.c. 9.57 c.c. Nitrogen found 79.8 Oxygen obtained = 0.0 1.147 c.c. 13.23 c.c. Temperature = 21°C. Barometer = 737 mm. Oxygen obtained at Normal = 0 1.033 c.c. 11.913 c.c. The 20 c.c. KMnO₄ = 112.48 m.g. 1 atom of oxygen = 7.967 c.c. Atoms oxygen found I II III from the molecule KMnO₄ = 0 0.129 1.496