18 



Art. 10. — K. Matsuno: 



That the dichro-salt gives the same curve (fig. II) as those of 

 tlie rest of the first class is to be explained by the fact that al- 

 though at first while the colour of its solution is yet green, it has 

 the configuration already mentioned, with the gradual transforma- 

 tion of the colour to indigo and at last to violet, the conversion of 

 the structure must take place as follows : 



— I — 



(green) 



CI 



XH3 

 (indigo) 



C1-. 



Cl^ 



V. 



(violet) 



CI2 



And [Co (NH3)3 (HP), CI] Clj will be also in equilibrium with 

 [Co (NHgjs (1120)3] CI3 in tlie water solution thus : 



[Co (NH3)3 (R,0), CI] C\, + -R,0 -^ [Co (NH3)3 (H20)3] CI3 



As regards this point, it will be fully discussed later. There 

 are many examples where, when the cldorocobaltaramines are 

 dissolved in water their chlorine atoms are easily replaced by 

 water molecules. The absorption spectra^'^ of [Co (NH3)5 CI] CI2 

 and [Co (NH3)5 HjO] CI3 in aqueous solution are identical, which 

 proves that the following substitution occurs to a certain extent: — 



I 



CI , 1 , NH, 



NH, 



CI2 + UoO 



NH3 



ILO, I . NH, 



NH, 



is^n, 



NH, 



CI3 



[Co CI H2O (NH3),] C]^ and [Co (H^O), (NH3),] CI3 have also the 

 same absorption curves, which are confirmed as follows: 



(1) Y. Shibata, Journ. College of Science, Imp. Univ., Tokyo, Vol. XXXVII, Art. 2, 1915. 



