Ob/fervations on rae and Steel. 17 
argillaceous ores of iron, is in many of a fuperior quality, 
and capable of producing bar iron equal to foreign, if treated 
in the fame manner : this, however, is out of the queftion in 
Britain, and can never bea fubject of general contempla- 
tion; though by thofe who have oppartunity the experiment 
might be made. 
Mott of the bog ores of Sweden and Ruffia contain lefs 
iron than fome of our iron-ftones, and give out a much lefs 
portion of volatile matter in torrefying; fo that fuch iron- 
ftones, by fevere torrefaction, might be reduced: to contain as 
much iron in 60 or 63 parts as in 100 when in a raw flate. 
Several of the fine iron-ftones found in Lanarkfhire are 
compofed as follows : 
Iron - “ Sa 40 
Carbonic acid, fulphur, &c. 38, which flies off intorrefying. 
Clay, lime and filex - 22 
1ooparts: fo that in 100 pounds 
of iron-ftone thus roafted, there would be contained of iron 
64‘ pounds.. Ores in fuch a ftate, and containing fuch a 
quantity of iron, would moft likely fmelt to great advantage 
in,contact with wood-charcoal. In diftinguifhing the qua- 
lities of crude iron, Mr. Collier has copied the French 
writers, without adverting to the difference between the 
fracture of crude iron manufactured with pit-coal, and that 
produced with the charcoal of wood; this laft is that de- 
{eribed by the. French metallurgifts. Crude iron manufac- 
tured with pit-coal is cither white, mottled, or grey: of the 
latter colour there are many fhades; the darker the grey, 
and the larger the grain, the fofter and more fufible is the 
quality of the iron. Thefe properties are exprefsly derived 
from, and dependent upon, the proportion of fuel ufed in re- 
duétion ; the greater the quantity of fuel, the larger and 
more brilliant will be the grains of the fraGture of the metal. 
The carbon contained in crude iron—for a// crude iron con- 
tains carbon—will be in exa& proportion to the relative quan- 
Vo, II. C tity 
