[10] Decolorized before time was taken. The results appearing in the table on the same horizontal lines are those of experiments made simultaneously, that is, the flasks in these experiments were immersed at the same time and in the same water-bath. These, that is the results appearing on the same horizontal line, and these only are comparable, since it was found that very slight differences in the temperature of the bath were of great influence on the length of time required for the reduction of the permanganate. It is clear that the rate of the reduction of the permanganate is greatly increased by increasing the quantity of the manganese oxide. After reduction of the permanganate, the contents of the flasks were in every case filtered and the filtrate tested by Crum’s reaction for the presence of manganese. No manganese was found. The absence of manganese in the filtrate shows that the reduction of the permanganate was not due to the formation of manganese nitrate, though it will be clear from the results of subsequent experiments that the presence of nitric acid exerts an influence on the rate of the reduction. B. In neutral solution. The condition were the same as under A, except that the nitric acid was omitted. Those flasks containing potassium permanganate and one, two and seven molecular equivalents respectively of the manganese oxide were immersed in the water-bath as before. No. I {containing one molecule of oxide and {one molecule KMnO₄ was reduced in 57 hours No. II {containing two molecules of oxide and {one molecule KMnO₄ was reduced in 35 hours No. III {containing seven molecules of oxide {and one molecule KMnO₄ was reduced in 2¾ hours C. In alkaline solution. The conditions were the same as under B, except that five molecules of potassium hydroxide were added for each molecule of the permanganate. No. I {containing one molecules of oxide for {each molecule KMnO₄ was reduced in 91¾ hours. No. II {containing two molecules of oxide {for each molecule KMnO₄ was reduced in 55(?) hours. No. III {containing seven molecules of oxide for {each molecule KMnO₄ was reduced in 10 hours. It appears that potassium permanganate is less easily reduced by manganese oxide in neutral than in acid solutions and in alkaline that in neutral solutions. The Reduction of Neutral Potassium Permanganate by Manganese Oxide at Ordinary Temperature. In these experiments, the manganese oxide used was prepared in the same manner as that in which the proportion of manganese to available oxygen was found immediately after its preparation to be 1.018 : 1.000