Perhaps the manufacture of iron(1*) would furnish the best
illustration of this subject; because, by having the actual price
of pig and bar iron at the same place and at the same time, the
effect of a change in the value of currency, as well as several
other sources of irregularity, would be removed.
288. At the present moment, whilst the manufacturers of iron
are complaining of the ruinously low price of their produce, a
new mode of smelting iron is coming into use, which, if it
realizes the statement of the patentees, promises to reduce
greatly the cost of production.
The improvement consists in heating the air previously to
employing it for blowing the furnace. One of the results is, that
coal may be used instead of coke; and this, in its turn,
diminishes the quantity of limestone which is required for the
fusion of the iron stone.
The following statement by the proprietors of the patent is
extracted from Brewster's Journal, 1832, p. 349:
Comparative view of the quantity of materials required at the
Clyde iron works to smelt a ton of foundry pig-iron, and of the
quantity of foundry pig-iron smelted from each furnace weekly
Fuel in tons of 20 cwt each cwt 112 lbs; Iron-stone; Lime-stone
Cwt; Weekly produce in pig-iron Tons
1.
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