AMMONIA-COBALT BASES. 59 



OXALATE OF XANTHOCOBALT. 



The oxalate of Xanthocobalt is precipitated when a solution of oxalate of 

 ammonia is added to one of the chloride, nitrate or sulphate of the base. After a 

 very short time yellow acicular crystals make their appearance, the separation 

 being greatly facilitated by strongly agitating the solution. The precipitate is to 

 be thrown on a filter, well washed with cold water and dried, first by pressure and 

 afterwards in pleno over sulphuric acid. As thus prepared, the salt has a pale 

 yellow color, and consists of fine needles, the form of which cannot be determined, 

 even under the microscope. It is nearly insoluble in cold and but very slightly 

 soluble in hot water. The solution is readily decomposed by boiling. The insolu- 

 bility of this oxalate and its characteristic appearance render it of great value in 

 detecting the presence of salts of Xanthocobalt. 



Oxalate of Xanthocobalt has the formula 



NO a .5NH 3 .Co 2 3 ,2C a 3 +5HO 



as appears from the following analyses : 



0.3191 grs. gave 0.1162 grs. sulphate of cobalt = 21.01 per cent, cobalt. 



0.2980 grs. gave 0.1650 grs, 



2.2520 grs. gave 0.7 07 5 grs. carbonic acid 



2.2850 grs. gave 0.7260 grs. 



The calculated results are 



Cobalt . 

 Oxalic acid 



THEORETICAL CONSIDERATIONS. 



The empirical constitution of the ammonia-cobalt bases being, as we believe, 

 established, it remains to offer an exposition of our views of their theoretical 

 structure. Claudet 1 and Weltzien 2 have endeavored to reduce the salts of Roseo- 

 cobalt and Luteocobalt to the type of ammonium, while Fremy has abstained from 

 adopting any particular theory, and gives, without comment, the results of his 

 analyses in the shape of empirical formulae. Claudet's view is necessarily errone- 

 ous, from the fact that his formula for what we term the chloride of Purpureo- 

 cobalt is incorrect, inasmuch as he assigns to it 16 in place of 15 equivalents of 

 hydrogen. Our own numerous analyses, as well as those of Eogojski and Gregory, 

 have clearly shown that the number of equivalents of hydrogen is fifteen. 



For an exposition of Weltzien's views we must refer to his paper; they appear 

 to us wanting in simplicity, since they require us to admit, not merely an equiva- 



: ' 





: < = 21.06 



" 



" 



joni( 



: acid 



= 25.70 

 = 25.99 



a 



oxalic acid. 



Eqs. 





Theory. 



Found. 



2 





21.14 



21.01 



21.06 



2 





25.81 



25.70 



25.99 



1 Phil. Mag. (4) II, 253. 



2 Annalen der Chemie und Pharmacie, XCVII, 19. 



