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kind of iron the most suitable for one purpose, another kind 
for another purpose. 
The properties of iron are found in Great Britain to 
vary,— 
1st. According to numerous conditions of the manufacture 
of the pig or cast metal, among which are — the kind of ore 
used, the flux, the fuel, the forms of the furnaces, the heat 
of the blast, the heat and degree of moisture of the atmo- 
sphere, and perhaps certain electrical and magnetic condi- 
tions which are not ascertained, but only suspected. 
2nd. According to the process adopted in the manufac- 
ture of pig iron into malleable iron. 
With respect to the ores, the varieties known in Great 
Britain are so numerous, that a mere geological and mine- 
ralogical catalogue of them would occupy far more time than 
could be allowed to an entire paper. To those members 
who have not yet examined the large official descriptive 
catalogue of the Great Exhibition, I would remark that in 
Class I., No. 427, they will find what I believe to be the 
most complete account of the iron making resources of this 
kingdom, as regards the ores. It is written from personal 
observation by my friend S. H. Blackwell, Esq., of Dudley ; 
and his collection of ores was deemed worthy of a Council 
Medal. To him I am indebted for many of the following 
particulars. 
The principal workable ores of Great Britain may be 
divided into three classes. 
1st. The carbonates of the coal measures. 
2nd. The haematites, or red oxides, of the carboniferous 
or mountain limestone formations, and also of the older 
rocks. 
3rd. The carbonates and brown hydrates of the oolites. 
The first class is subdivided into argillaceous and carbon- 
aceous iron stones. The argillaceous iron stones are ex- 
