1. The photochemical reversible reaction of the alkaline solution of malachite green was studied with the quartz-mercury-lamp, and its nature was discussed. 2. The reaction velocities were determined both in the light and the dark reaction, using Nutting’s spectro-photometer. The former is proportional to the intensity of light and the latter to the concentration of the alkali added. 3. The temperature coefficient of the reaction velocity of the light reaction was found to be unity at the interval between 25° and 35°C. 4. Equation of the reaction of first order was derived with approximation for the light reaction.
The substance which was formerly supposed as 2,6-dioxydiphenyl was shown to be 2-oxydiphenylene oxide (III). A new phenol was obtained, the formula of which was shown to be dioxydiphenylene oxide C12H6O (OH)2. Two hydroxy groups seem to be in 2 and 2′ positions from the mechanism of its formation and its absorption spectrum.