AMMONIA-COBALT BASES. 



47 



The constitution of the neutral carbonate appears to be represented by the 

 formula 



6NH 3 .Co 2 3 ,3C0 2 +7HO. 



2495 grs. gave 0.1220 grs. sulphate of cobalt = 18.61 per cent, cobalt. 

 0.3518 grs. gave 0.0786 grs. carbonic acid = 22.34 per cent. 



The formula requires 





Eqs. 





Found. 



Cobalt . 



. 2 



18.79 



18.61 



Carbonic acid . 



. 3 



21.01 



22.34 



The excess of carbonic acid and the deficiency in cobalt, are doubtless due to the 

 presence of a portion of the acid carbonate. The neutral carbonate loses its water 

 of crystallization in dry air, and becomes opaque, with the lustre of porcelain, like 

 many other hydrated salts of this base. 



The acid carbonate of Luteocobalt is most readily prepared by passing a current 

 of carbonic acid gas into a solution of the neutral salt. The acid carbonate usually 

 separates, after a very short time, in the form of large brown-red or sherry-wine 

 colored crystals, which are less soluble than those of the neutral carbonate. Accord- 

 ing to Prof. Dana, the crystals of this salt belong to the monoclinic system, and 

 closely approach Barytocalcite in form. Fig. 21 represents a crystal of this salt. 







ii = 108° 16' 











I = 770 40' and 102° 



20' 





I: 



I = 85° 54' ' 





a:b : c = 0.7219 : 1 : 0.8398 



O 



1 = 139° 50' 





C = 71° 44'. 



I 



1 = 142° 30' 











-2» = 111° 46 







In Barytocalcite the angle corresponding to O : ii =106° 54' and that corres- 

 ponding to I : I = 84° 52'. 



The acid carbonate of Luteocobalt retains its water of crystallization in the air, 

 but loses it under the air-pump. The salt is particularly interesting as being the 

 only acid salt of Luteocobalt which we have as yet been able to obtain. The 

 formula of this salt is 



6NH 3 .Co 2 3 ,3Co 2 +HO,C0 2 +5HO 

 as the following analyses show : 



0.4715 grs. gave 0.2246 grs. sulphate of cobalt = 18.12 per cent, cobalt. 

 1.0506 grs. gave 0.2830 grs. carbonic acid = 26.93 per cent. 



The formula requires 





Eqs. 





Found. 



Cobalt . 



. 2 



18.04 " 



18.12 



Carbonic acid . 



. 4 



26.91 



26.93 



The very distinctly marked triacid character of Luteocobalt, considered as a base, 

 renders it, to say the least, improbable that the formula of this salt should be 

 written 



6NH s .CooO,.4COo+6HO. 



