496 Intelligence and Miscellaneous Articles. 
and explicitly attributed it to him. I find on reperusing the abstract, 
that though such is the case, this discovery is also included aléng 
with the other facts in the general theory proposed, and that from its 
being apparently a necessary consequence of the theory the merit of 
its originality might appear lessened. Such however is not the 
case: what the theory does is rather to confirm its truth, of which 
Professor Forbes has brought abundance of evidence from other 
sources. 
If you will give this Note a place in your forthcoming Number 
you will oblige, 
Gentlemen, yours, &c., 
Liverpool, March 10, 1843. JouHN SUTHERLAND. 
ON THE COMBUSTION OF IRON PYRITES FOR THE MANUFAC- 
TURE OF SULPHURIC ACID. 
To the Editors of the Philosophical Magazine and Journal. 
GENTLEMEN, 
In the combustion of iron pyrites for the purposes of sulphuric 
acid manufacture, it is well known that sulphate of iron is more or 
less formed ; the proportion will depend on the quality of the pyrites, 
and the degree of perfectness with which it is burnt. On examina- 
tion, I find that the sulphate of iron formed is the sesquisulphate, 
whose symbol is Fe,0,;+3 SO,. A careful analysis of the average 
run of pyrites ashes gives 3°20 per cent. as sulphuric acid. 
It was my intention to have sent you a more detailed account of 
my experiments on this subject, had not other demands on my time 
obliged me to leave them imperfect ; should returning leisure enable - 
me to finish them, if acceptable they shall be at your service. 
I remain, Gentlemen, your obedient Servant, 
April 23, 1843. A SUBSCRIBER. 
OXIDE AND PEROXIDE OF BISMUTH—BISMUTHIC ACID. 
M. Frémy states that when hydrated oxide of bismuth is boiled 
in a solution of alkali, a period arrives in which the precipitate, 
which was originally white, is converted into a considerable quantity 
of small yellow brilliant needles, which are anhydrous oxide of 
bismuth. 
He also states, that by acting on oxide of bismuth by the alkalies 
at a high temperature, he has been able to obtain peroxide of bis- 
muth of perfect purity. This oxide has been mentioned by several 
chemists, but has not hitherto been obtained in a state of purity. 
M. Jacquelain found that when oxide of bismuth is heated with an 
alkali in a silver crucible, it is peroxidized and combines with the 
alkali; but he could not obtain the peroxide in a separate state. 
M. Frémy obtained in the same way bismuthate of soda, but he 
found that if this salt is boiled with an excess of soda, the acid is dehy- 
drated and quits the alkali. The peroxide thus obtained is of a puce 
colour, like the peroxide of lead, and may be washed with nitric acid 
without being decomposed. By analysis this oxide was found to be 
