JOURNAL OF THE COLLEGK OF SCIENCE, TOKYO IMPERIAL UNIVERSITY. 



VOL. XLI., ART. 11. 



The Coagulation of Arsenious Sulphide Sol by 

 Cobaltic Complexes. 



By 

 Kichimatsu MaTSUNO, Eiijaku^hi. 



Introduction 



The valency of inorganic complex ions is usually determined 

 b}^ measuring their electric conductivities in solutions [Werner 

 aui] MioLATi: Zs. physik. Chem., 12, 3Ö : Ï4, 506(1894)]. 



This method is dependent to a certain extent on the migra- 

 tion velocity of the ions. It is well known that the valency of a 

 coagulating ion has a great effect in determining its coagulating 

 powcA*. Galecki [Zs. Elek. chem, 14, 7(37, (1908)] utilised this fact 

 in determining the valency of beryllium by coagulation experi- 

 ments with arsenious sulphide sol. Freundlich [Zs physik. 

 Chem., 89, 504, (1912)] has shown that it is possible to follow the 

 change in the valency of the cation of a cobaltic complex Ijy 

 coagulation experiments with arsenious sulphide sol. But such 

 experiments with cations of a valency greater than three have not 

 been tried so far. It is now generally accepted that the so-called 

 valency law of Schulze is a rough generalisation [Bancroft, J. 

 Physic. Chem., 19, 348, (1915): Brit. As. Rep. (1918), Wo. 

 Ostwald; Koll. Zeitsch., 26 (1920), 69]. Experiments with 

 complex cations having a valency up to six is of interest as a test 

 of so-called valency law. It Mill be seen from the sequel that tlie 

 valency of the cation has a predominant effect and that the valencies 

 determined by coagulation experiments agree perfectly with the 

 usual formulae given to these salts. 



