Dr. E. J. Mills on certain Cobaltamines. 255 



IV. Theoretical Considerations. 



(1) The action of water upon the polyammoniacal cobaltic 

 chlorides would be intelligible without further delay, if it con- 

 sisted merely in the production of sal-ammoniac, hydrous dico- 

 baltic teroxide, and ammonia. Equations in accordance with 

 this hypothesis have been shown, however, not to correspond 

 with experiment. Abundance of sal-ammoniac is, indeed, inva- 

 riably formed ; but tetracobaltic pentoxide is the oxide precipi- 

 tated, and the ammonia which is not required to constitute sal- 

 ammoniac is never wholly recoverable in the free state. 



The constant afterpresence of a minute quantity of hydric 

 nitrate and cobaltic chloride furnish, I believe, a key to this pro- 

 blem, which may be interpreted as follows. Jn the first place, 

 the equation* of movement (which must not be understood sta- 

 tically), 



2[CoCP.5NH 3 ]=2CoCl 2 + 10NH 3 + Cl 2 , . . (a) 



expresses the momentary genesis of cobaltic chloride, ammonia, 

 and chlorine as such. The two latter act upon each other so as 

 to form (nitrogen ?) ammonia, hydric nitrate, and sal-ammoniac, 

 whereby they arrive at a permanent condition of repose. The 

 cobaltic chloride attains that condition only after performing 

 work which may be formulated thus : — 



2CoCl 2 + 2[CoCl 3 .5NH 8 ]+(5 + n)H 2 = Co 4 5 .7iH 2 0"\ 



+ 10[NH 3 .HC1] J ( } 



A fresh portion of the original substance hereupon assumes the 

 properties of transference indicated in (a), and then the statical 

 properties pointed out in (b) and the text immediately preceding 

 it. But as (a) is necessarily in advance of (b), it is evident 

 that a small amount of cobaltic chloride must eventually remain 

 at the close of the reaction. The proportion of chlorine avail- 

 able for oxidizing-purposes is one-sixth of all that is present, and 

 is equivalent to 1*02 per cent, of ammonia for the hexammonio- 

 chloride, on the hypothesis 



3C1 2 + 2NH 3 =N 2 + 6HC1, 



* This is the simplest equation suitable [for the purpose. But as I find 

 that cobaltic sesquioxide and sal-ammoniac, when digested under pressure 

 with water, give rise to traces of cobaltic chloride, those who prefer it may 

 adopt the systems 



2[CoCl 3 . 5NH 3 ] + (3+rc)H 2 0= Co 2 O 3 . rcH 2 0+ 6[NH 3 . HC1]+4NH 3 

 and 



Co 2 O 3 .«H 2 O+6[NH 3 .HCl]+4NH 3 =2CoCl 2 -f-10NH 3 +(3+w)H 2 O-f-Cl 2 



instead of (a). They amount nearly to the same thing, and are possibly 

 better than the single equation given above. 



