A NEW CLASS OF SALTS. 
515 
And probably the ferroso-ferric oxide is transformed at the expense of the oxyg^en of 
water into ferric oxide, the hydrogen forming ammonia with nitrogen, 
6Fe0+3H0+N=3Fe203+NH3. 
29. In giving the above equation, the blue sulphur compound was supposed to 
consist of nitroprusside of sodium with 3 equivs. of sulphuret of sodium attached. 
The following calculation shows that this is an expression of the analysis : — 
Calculated. 
Mean experiment. 
5 Iron . 
. 140 
17-36 
16-84 
8 Sodium . 
. 186 
23-07 
22-60 
24 Carbon . 
. 144 
17-86 
17-27 
3 Sulphur . 
48 
5-95 
5-71 
6 Hydrogen 
6 
0-74 
0-74 
15 Nitrogen . 
. 210') 
35-02 
36-84 
9 Oxygen . 
. 72 j 
806 
100-00 
100-00 
The approximation is sufficiently near when the difficulty of getting the substance 
in at all a stable state is considered. Two views might be taken of the constitution 
of this singular compound (1), that it is nitroprusside of sodium with 3 equivs. of 
sulphuret of sodium attached — 
Fcg Cyi 2 3N(), 5Na+3NaS+6HO ; 
but this would scarcely account for its extreme facility of decomposition ; it may 
therefore be supposed that caustic soda is attached to the salt, as we have seen that 
it can be, in studying the action of alkalies on the nitroprussides, and that the sulphur 
has taken the place of the oxygen, thus ; — 
Fe 5 Cyi 2 3NS, 5Na+3NaO+6HO. 
Either of these formulae would suit the analysis ; in support of the latter may be 
adduced the fact observed by Gregory, that sulphuret of nitrogen in the presence 
of caustic alkalies acquires a deep transitory amethyst colour, which, on disappear- 
ing, evolved ammonia, a description exactly accordant with the present case. 
Action of Sulphuretted Hydrogen on the Nitroprussides. 
30. Sulphuretted hydrogen decomposes the soluble nitroprussides. The products 
of transformation are most conveniently obtained in the following way: — Nitro- 
prusside of sodium is dissolved in the smallest possible quantity of cold water, and 
three or four times its volume of alcohol is added to the solution. Sulphuretted 
hydrogen is now passed through this alcoholic solution. Sulphur, prussian blue, 
and ferrocyanide of sodium, are very gradually precipitated ; the action, however, is 
very slow, and must be long continued. The alcoholic solution is now of a reddish 
olive-brown colour. When the sulphuretted hydrogen has ceased to act, this super- 
natant brownish liquid gives no coloration when mixed with an alkaline sulphide. 
