from other Metals. 87 
with nitric acid. It is then to be just neutralized, while in a 
state of ebullition, by carbonate of ammonia. The whole of the 
iron to the last atom, is precipitated, and the whole of the other 
metals present (which I suppose to be manganese, cerium, nickel, 
and cobalt) remain in solution. 
The precautions necessary to ensure success in this process are 
few and simple. In the first place, the solution must contain no 
oxide of manganese or cerium above the first degree of oxidation, 
otherwise it will be separated with the iron. It is scarcely pro- 
bable in ordinary cases that any such should be present, the 
protoxides only of these metals forming salts of any stability ; 
but should they be suspected, a short ebullition with a little sugar 
will reduce them to the minimum. _ If nitric acid be now added, 
the iron alone is peroxidized, the other oxides remaining at the 
minimum*, Moreover, in performing the precipitation the me- 
tallic solution should not be too concentrated, and must be agi- 
tated the whole time, especially towards the end of the process ; 
and when the acid reaction is so far diminished that log-wood 
paper is but feebly affected by it, the alkaline solution must be 
added cautiously, in small quantities at-a time, and in a diluted 
state. If too much alkali be added, a drop or two of any acid 
will set all right again; but it should be well observed, as upon 
this the whole rigour of the process depends, that no incon- 
venience can arise from slightly surpassing the point of precise 
neutralization, as the newly-precipitated curbonates of the above 
enumerated metals are readily soluble, to a certain extent, in 
the solutions in which they are formed (though perfectly neu- 
tral). In the cases of cobalt and cerium, this redissolution of 
the recent precipitate formed by carbonate of ammonia is very 
considerable, and a solution of either of these metals, thus ini- 
prégnated with the metallic carbonate, becomes a test of the 
presence of peroxide of iron, of a delicacy surpassing most of the 
reagents used in chemistry, the minutest trace of it being in- 
stantly thrown down by them from a boiling solution, provided 
no marked excess of acid be present. ‘To be certain however 
that we have not gone too far, it is advisable, after separating 
the ferruginous precipitate, to test the clear liquid, while hot, 
with a drop of the alkaline carbonate. If the cloud which this 
produces be clearly redissolved on agitation, we may be sure that 
only iron has been separated. If otherwise, a little acid must 
* Dr. Forschammer, in a paper recently published in Thomson’s Annals 
of Philosophy, contends that the proto-salts of manganese are absolutely void 
of colour. ‘To this I can only say, that I have not succeeded in depriving 
the muriate of its pale rose colour by any length of ebullition with sugar or 
alcohol, after which, however, net a trace of deutoxide could be detected 
init. I cannot help regarding the process herg proposed for freeing man- 
ganese from iron as preferable to that of Dr. F. 
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