1. By means of the coagulation of arsenious sulphide sol, the mechanism of the substitution reactions, (Remark: Graphics omitted.) has been studied, and it has been proved that this change is a monomolecular successive reaction. 2. The velocity constants of the first and second reaction of the substitution above mentioned has been calculated as k1=0.011 and k2=0.0031. 3. The time when the intermediate compound would be in its maximum concentration could be computed. The author is indebted to Prof. Yuji Shibata for his kind advice and to Mr. Haruto Tsukamoto, professor of chemistry in the Hamamatsu Technical High School, for his kind assistance.
The equilibrium of the reciprocal salt pair [K2, (NH4)2]–[SO4, CrO4] was studied at 25°. There exist two complete series of solid solutions in equilibrium with liquid solutions. The compositions of the solid solutions have been determined by a special method. The equilibrium of the system has been graphically represented using Janeck’s square diagram.