(1) The velocity of the oxidation of ferrous hydroxide by means of air was studied. The rate of the oxidation was independent of the quantity of ferrous hydroxide present in the reacting vessel, and the values of the velocity constants were almost the same as those of the velocity constants of the oxidation of sodium sulphite or stannous hydroxide under the same conditions. (2) The effect of temperature was small. (3) Sodium hydroxide decreases the velocity of the oxidation, the mechanism of which will be explained by the considerations that the oxidation velocity thus measured is no other than the dissolution velocity of oxygen under the conditions above described, and that sodium hydroxide decreases the dissolution velocity of oxygen into the solution.
1. Molecular compounds of diketopiperazine with copper chloride and bromide were prepared. 2. The formation of such compounds in aqueous solution with formulae other than those obtained in solid state was ascertained. 3. The meaning of these molecular compounds for the chemistry of protein was discussed.