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XX. On the separation of Iron from other metals. By J. F. W. 
Herschel, Esq. F. R. S. 
Read April 5, 1821. 
.An easy and exact method of separating iron from the 
other metals with which it may happen to be mixed, has 
always been a desideratum in chemistry. Every one con- 
versant with the analysis of minerals is aware of the difficulty 
of the problem, which indeed is such that, in experiments 
conducted on any thing like a large scale, it might hitherto 
be regarded as insuperable. Irr consequence of this, and of 
the importance of the enquiry, there is hardly a chemist of 
eminence who has not proposed some process for the pur- 
pose, but (with the exception of that which depends on the 
insolubility of the persuccinate of the obnoxious metal, which 
I have not tried, and which is too expensive to be resorted to 
for any but the nicer purposes of analytical research) they 
are all of them either inadequate to the end proposed, intole- 
rably tedious, or limited in their application. That which I 
have now to propose, on the other hand, is liable to none of 
these objections, being mathematically rigorous, of general 
application, and possessing in the highest degree the advan- 
tages of facility, celerity, and cheapness. It is briefly this : 
The solution containing iron, is to be brought to the maxi- 
mum of oxidation, which can be communicated to it by 
boiling with nitric acid. It is then to be just neutralized 
while in a state of ebullition , by carbonate of ammonia. The 
