Double Chlorides, Bromides and Iodides. 419 



The previously described double halogen salts of cobalt and 

 nickel, as far as I have been able to learn, correspond to two 

 types of the caesium salts, and are as follows : 



2 : 1 Type. 1 : 1 Type. 



(NH 4 ) 2 CoF 4 . 2H 2 NH 4 CoCl 3 . 6H 2 



(NH 4 ) 2 NiF 4 . 2H o NH 4 NiCl 3 . 6H 9 



KCoF 3 . H„0 

 KNiF 3 . H" 2 

 NaCoF 3 .H 2 

 NaNiF 3 . H 2 



The following table gives approximately the composition of 

 the solutions from which the caesium salts under consideration 

 were crystallized by concentration and cooling. 



Gs : Co or Ni {Atoms.) 



Cs 3 CoCl 6 





From 



12: 



; 1 



to 6:1 



Cs 2 CoCl 4 





c< 



6: 



: 1 



" 0-4 : 1 



CsCoCl 3 . 



2H 2 



(C 



0-4: 



: 1 



" syrupy solution of CoCl 2 



Cs.CoBr, 





cc 



2 : 



: 1 



"1:1 



Cs 2 CoBr 4 





(C 



1 : 



;1 



" syrupy solution of CoBr, 



Cs 2 CoI 4 





it 



1 



:4 



"1:16 



CsNiCl 3 





CC 



12 



: 1 



" syrupy solution of NiCl„ 



CsNiBr, 





u 



2-5: 



1 



" syrupy solution of NiBr 2 



More or less of the corresponding halogen acid was present 

 in each case, and an increase of this was apparently equivalent 

 in effect to the addition of the cassium halide. In the case of 

 the two nickel salts, a rather large amount of the acid was 

 desirable, for if it was not present, the salts appeared only 

 upon heating the concentrated solutions and dissolved when 

 they cooled. 



The color of the chlorides containing cobalt is a magnificent 

 blue, the bromides and the iodides containing the same metal 

 are green, while the two nickel salts are yellow. The two 

 nickel salts form almost microscopic crystals. The two salts of 

 the 3 : 1 type were obtained in crystals having a diameter of 

 about 5 mm , apparently combinations of the cube and octahe- 

 dron. The salts of the 2 : 1 type form large plates or prisms, 

 the habit evidently depending upon the composition of the 

 solutions from which they crystallize. The salt CsCoCl 3 . 2H 2 

 forms rather small plates. Besides the blue salt just mentioned, 

 a red csesium-cobalt chloride of the 1 : 1 type was obtained 

 which lost water of crystallization so readily, with change of 

 color, that it could not be analyzed in its original condition. 



The compound Cs 2 CoI 4 is deliquescent, while the other salts, 

 here described, are stable. All the salts are whitened when 

 brought into contact with water or alcohol, evidently on 

 account of decomposition. 



Am. Jour. Sci.— Third Series, Vol. XLVIII, No. 287.— Not., 1894. 

 27 



