The Coagulation cif Arsenious Sulphide Sol by Cobaltic Complexes 15 



2. — The valency of many simple and complicated cobaltam- 

 mines was determined by means of the limiting concentration. 



o. — r>y utilising the valency effect on the sol, the chemical 

 changes in aqueous solutions of some cobaltainmines has been 

 followed. The results are in agreement with those obtained from 

 conductivity meajSurements and absorption of light. 



The author would like to express his sincere gratitude to Prof. 

 Y. Shtbata and Prof. K. Ikeda for their kind advice. His best 

 thanks are due to Dr. JNIiyasawa for his assistences. 



(The Laboratory of Inorganic Chemistry, College of Science, 

 Imperial University, Tokyo.) 



Published march 31st, 1921. 



