Steel. 
281 
porting the sides and bottoms of the pots, and for direct- 
ing the flame equally round them. The great object is 
to communicate to the whole an equal degree of heat in 
every part. The fuel is put in at each end of the fire- 
place, and the fire is made the whole length of the pots, 
and kept up as equally as possible.” 
On this paper of Collier’s it may be remarked, that the 
bars are often put into iron as well as brick or earthen 
cases, and indeed in England generally so — that although 
the heating and cooling may occupy altogether a dozen 
idays, it does not require more than a dozen hours of white 
, heat, to convert into good blistered steel, bar iron the 8th 
of an inch thick — that steel of cementation, blistered or 
German bar steel, should be made of the very best, and 
best worked iron that can be procured ; generally of Swe- 
dish iron, the whole of which used to be bought up by 
2 or 3 houses in England. If not well hammered in its 
state of iron, it will shew the want of uniformity in its tex- 
ture, much more as steel -Cast steel is always made 
originally from bar steel, or steel of cementation equal 
proportions of limestone and cinders, is far too much of 
limestone : one part of limestone to 3 or 4 of cinders is 
more common; and the English rich Cumberland ore, 
worked with wood charcoal, requires no more than one 
twentieth of limestone— there is hardly any such thing 
in use at an English blast furnace as bellows ; they are 
supplied with air either from cast iron drums or cylinders 
worked with the power of water or steam ; or by a water 
blast ; and the air is condensed so as to support a column 
of 6 inches of mercury ; by which compression from 15 
to 1800 cubic inches of air will pass through the discharg- 
ing pipe of 3 inches wide in a minute- -Mr. Collier 
has not noticed the common process of puddling introduce 
ed by Mr. Cort, which has succeeded in practice ; and 
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