272 
Steel. 
bination would be dissipated*. I shall at present confine 
my remarks to the operations performed on iron in Shef- 
field and its neighbourhood, from whence various com- 
munications have been transmitted to me by resident 
friends, and where I have myself seen the operations re- 
peatedly performed. The iron made in that part of York- 
shire is procured from ores found in the neighbourhood, 
which are of the argillaceous kind, but intermixed with 
a large proportion of foreign matter. These, however, 
are frequently combined with richer ores from Cumber- 
land and other places. The ore is first roasted with cin- 
ders for three days in the open air, in order to expel the 
sulphureous or arsenical parts, and afterwards taken to the 
furnaces, some of which are constructed so that their in- 
, m 
ternal cavity has the form of two four- sided pyramids! 
joined base to base ; but those most commonly used are i! 
of a conical form, from forty to fifty feet high. The fur- 
nace being previously heated in various proportions accor- 
ding to the nature of the ore, is charged at the top with,! 
coal-cinder and limestone. The limestone acts as a flux, 
at the same time that it supplies a sufficient quantity of 
earthy matter, to be converted into scoriae, which are ne- 
cessary to defend the reduced metal from calcination, when 
it comes near the lower part of the furnace. The fire is 
lighted at the bottom ; and the heat is excited by means 
of two pair of large bellowst blowing alternately. Thq 
quantity of air generally thrown into the furnace is from 
1000 to 1200 square feet in a minute, The air passes 
through a pipe, the diameter of which is from two inches 
* It is the opinion of some metallurgists, that a partial abstras* 
tion of oxygen takes place, by plunging hot metal into cold water. 
t Rather two inverted cones, of which the base of the larger rests 
upon the base of the smaller. 
;£ These are now discarded and large cast iron cylinders subst itu- 
ted in their stead. 
H From 1500 to IS00 out of a pipe of or 3 inch bore 
