262 



On comparing the molecular rotation of the bromides, iodides Sind 

 nitrates of the two series: 



Tri-ethyJenediamine- 



Cobalti- Bromide -. 



[M'Id = ± 6000° 



Tri-ethylenediamine- 

 Rhodium- Bromide : 

 [M]n= ±3500° 



Tri-ethy lenediam ine- 



Cobalti-lodide -. 



[M]d= ± 6120° 



Tri-ethylenedinmine- 



Ehodium- Iodide : 



[M]d= ± 3020° 



Tri-ethy lenediam ine- 



Cobalti- Nitrate: 

 [M^D = ± 4600° 



Tri-ethy lenediamine- 

 Rhodium- JS itr ate : 

 [M]d= ± 3600° 



we see that the Co-salts, besides exhibiting a much greater rotation- 

 dispersion, also possess a much greater absolute rotation. 



This fact will appear conceivable, if we bear in mind the very 

 different chemical nature of the two isomorphous central atoms, and 

 the rather appreciable difference in their atomic weights (59 and 

 103). 



Some experiments on the properties of the analogous /r-salts in 

 this respect, are planned in this laboratory. 



Laboratory for Inorganic and Physical Chemistry 

 of the University, Groningen, Holland. 



I 



