20 



Art. 10.— K. Matsimd : 



lias already studied the constitution of I ^^ h^O (2) ^^^^ Cl<,('^ two 



water molecules of which are coordinated in the cis-position, 

 thus : 



, HjO 



/ 



CIs 



The compounds belonging to this series are general!}^ more 

 stable than those of the first class, while tlie latter seems to have 

 a great tendency to be converted into the former. From the 

 fact that the absorption curve of the cis-diaquodiethylenedia- 

 niine cobaltic chloride (fig. Ill) is analogous to the curves of 

 [Co CO3 (NHg),] CI, [Co CA (NH,),] CI and [Co CO3 ey^g] CI, we can 

 affirm that, when tlie water molecules coordinate to a cobalt atom 

 to form a complex salt, then unite with the central atom by tlie 

 residual affinity of the oxygen of water as illustrated below : 



OH., 



-7 OR,. 



NH. 



>C0. 



NH, 



NH, 



o -c 



KH, 



The chlorotriaquodiaramine cobaltic sulphate must have the 

 following configuration. For its absorption curve (fig. IV) is very 

 similar to that of the cis-diaquodiethylenediamine cobaltic chloride, 



(1) B.T., 40, 285, 1907. 



