Flask No. I Manganese oxide, black, = 150 m.g. N/10 nitric acid = 14.93 c.c. [= Mn in KMnO₄ in No. II or No. III] Water = 27.46 c.c. [Total solution = 42.39 c.c.] Flask No. II Potassium permanganate = 20 c.c. = 117.71 m.g. N/10 nitric acid = 22.39 c.c. [= K and Mn in KMnO₄] [Total solution = 42.39 c.c.] Flask No. III Potassium permanganate = 20 c.c. = 117.71 m.g. N/10 nitric acid = 22.39 c.c. [= K and Mn in KMnO₄] Manganese oxide, black = 150 m.g. [Total solution = 42.39 c.c.] The first two results are from experiments in which the action was stopped at the first loss of the color of potassium permanganate. The last two are the results from experiments in which the action was stopped after the oxide had settled leaving a clear colorless supernatant liquid. The amount of oxygen given off in any one case is expressed in the table as the number of atoms of oxygen derived from each molecule of potassium permanganate, as follows: A = N/10 nitric acid. No. of molecules. ------------------+-------------------------+-------------------- Flask I | Flask II | Flask III ------------------+-------------------------+-------------------- Black | Potassium | Potassium oxide A |permanganate A | permanganate A 150 m.g. | 20 c.c. = | 20 c.c. | 117.71 m.g. | = 117.71 m.g. ----------------------+-------------------------+---------------- 1 2 hours. 0.00 2 0.18 3 1.337 3 2 2¼ hours 0.02 ” 0.24 ” 1.335 ” 3 2½ hours 0.02 ” 0.44 ” 1.402 ” 4 4½ hours 0.00 ” 0.55 ” 1.362 ”