No. 161.] 
41 
facture is prosecuted in some parts of the United States, and has 
recently been commenced in Canton, St. Lawrence county, where 
this ore occurs in vast quantities. In those cases where the py- 
rites is mixed with alumine or clay, it may also be employed in 
the manufacture of alum. 
In some instances this change takes place spontaneously. The 
sulphuret of iron, being composed of sulphur and iron; by the 
agency of the oxygen of the air, the iron is oxidated, and the sul- 
phur is converted into sulphuric acid, the result of which is the 
formation of sulphate of iron. It is in this way that we are to 
account for the occurrence of native copperas in the vicinity of 
beds of sulphuret of iron. And this deserves to be noticed as an- 
other of those natural chemical processes, the careful study of 
which has led to its imitation by the manufacturer — a striking 
proof of the benefits derived from well directed chemical re- 
searches. 
A fact of some interest in regard to this mineral, is its occur- 
rence in comparatively small quantities in the ores usually employ- 
ed in furnishing iron. When we advert to the injurious effect 
which sulphur has on iron, and to the ease with which the sulphu- 
ret of iron is decomposed by heat, it will not be difficult for us to 
understand how this mineral, although in minute proportion, may 
be a most troublesome ingredient of an ore. Its presence can in 
most cases be detected by the eye, or by the sulphurous odour 
which is given off when the ore is subjected to roasting — an ope- 
ration which should in no case be omitted where it occurs in any 
considerable proportion. 
Arsenical Iron — Mispiekel. — The compounds of arsenic and iron 
known by these names, occur in some parts of the State, and are 
equally, if not more injurious to the manufacture of iron than the 
pyrites. They are found in Dutchess and in Orange counties; in 
the latter also the titaniferous iron is met with. Arsenical iron 
associated with tabular spar and colophonite abounds in the town 
of Lewis, Essex county. 
Having thus laid before you an account of our principal deposi- 
tories of iron ore, it is necessary to the completion of my design, 
and quite consistent with the popular nature of this report, to add 
some remarks upon the present condition of the manufacture of 
[Assem. No. 161.] 6 
