OF ARTS AND SCIENCES. 37 



Sulphato-platino-chloride, Co^CNHg) 12(86 J^Cl+PtCl^ 



Cerous double sulphate 



(Wing), Co,(NH3)i,(SOj3+3SO,Ce-fOH, 



Ceric double sulphate (Wing), Co2(NH3)i2(SOj3+Ce2(SO,),+ok3 



Hyperiodides, Hyperbromides, ^c. — When bromine is added to solu- 

 tions of the salts of roseocobalt, purpureocobalt, and luteocobalt, yellow 

 or orange crystalline precipitates are formed which contain bromine in 

 excess of the quantity of the chlorous element necessary to form a 

 normal salt. These compounds give off bromine readily on drying, 

 and cannot be obtained pure for analysis. Iodine behaves in a sim- 

 ilar manner with some of the cobaltamines, but not with all. I have 

 already described the hyperiodides of the xanthocobalt and croceoco- 

 balt series, and shall content myself with having established the exist- 

 ence of this class of compounds which bear a certain resemblance to 

 the hyperiodides of the higher alkaloids. 



FORMATION AND PREPARATION OF THE COBALTAMINES. 



In our joint memoir Genth and I confined our attention almost 

 exclusively to the determination of the constitution of the cobaltamine 

 salts and to their desci-iption, reserving a detailed study of the mode 

 of formation of these compounds for the second part of our work. 

 Circumstances prevented for many years a resumption of the subject. 

 In the mean time the excellent memoir of Dr. Friedrich Rose * has 

 appeared, and in this the formation of the cobaltamines by the oxida- 

 tion of ammoniacal solutions of cobaltic salts has been carefully studied. 

 The memoir contains also the fullest history of the whole subject wiiich 

 has yet been given. Eose's results may be epitomized as follows: 

 An ammoniacal solution of cobaltic chloride absorbs oxygen, forming 

 a brown solution which, after some days, becomes red by loss of oxy- 

 gen. The red solution can again absorb oxygen and become brown. 

 "When strong chlorhydric acid is added to the brown solution, carbonic 

 dioxide and chlorine are evolved, while a reddish-yellow precipitate is 

 formed. This precipitate is a mixture of the chlorides of pur|)ure()-, 

 roseo-, and luteocobalt, of a black salt for which no rational formula 



* Untersuchungen iiber ammoniakalische Kobalt-Verbindungen. Von Dr. 

 Friedrich Rose. Heidelberg, 1871. 



