Ammoniacal Compounds of Cobalt. ^f 



that it is a sesqui-conjugated compound, if it may be so called, 

 being composed of 3 equivalents of the salt united with 2 equi- 

 valents of the adjunct. 



Another way of grouping the atoms of this compound is the 

 following, proposed by Mr. Graham :-^^ '^ '' -*:;.- jirt; ? inm 



fNH^Co^ /d ]>?:!!?oqropoMi> «i il&p. orii 



Here NH^ Co^ represents an ammonium in which 2 equivalents 

 of hydrogen are replaced by 2 equivalents of cobalt; while NIP 

 NH'* I'epresents an ammonium in which 1 equivalent of hydrogen 

 is replaced by ammonium itself, as the hydrogen of ammonia is 

 replaced by ethyle, methyle, &c. in Wurtz's and llofmann's bases. 



CINJ i^o + 2ClNJ ^^ 



N{g 



Co2 + '^^^^^\NH4 



The compound would then be viewed as a double salt, composed 

 of 1 equivalent of a chloride of cobalt-ammonium and 2 equiva- 

 lents of a chloride of ammonium, in which the fourth atom of 

 hydrogen is replaced by ammonium. 



This peculiar compound has the property of forming double 

 salts with bichloride of platinum and bichloride of mercury. 



Double salt with bichloride of platinum. — On adding a warm 

 solution of the salt to bichloride of platinum in excess, a silky 

 crystalline buff-coloured precipitate falls down, much less soluble 

 than the salt itself; it may therefore be well washed with water, 

 thrown on a filter and dried. 



12 grains of this double salt were fused with carbonate of 

 soda, dissolved in hot water and filtered, to separate the platinum 

 and oxide of cobalt. The solution neutralized with nitric acid 

 and precipitated with nitrate of silver gave 20* 11 grs. AgCl = 

 4"975 CI =41 '6 per cent. The filtrate of platinum and oxide of 

 cobalt ignited was treated with boiling hydrochloric acid, which 

 dissolved out the cobalt, and left 4*05 platinum = 33' 75 per cent. 



18*59 grains of double salt reduced by hydrogen gave 8*06 

 mixed metals =43-35 per cent., giving 9'60 per cent, for the 

 cobalt. The double salt is consequently composed of 1 equiva- 

 lent of the new compound and 2 equivalents of bichloride of 

 platinum. 



Calculated. 



