Page:On the economy of machinery and manufactures - Babbage - 1846.djvu/269

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ON OVER-MANUFACTURING.
235
"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.
Ironstone. Limestone. Weekly
produce in
pig-iron.
Tons. Cwt. Tons.
1. With air not heated and coke 7  31/4 15  45
2. With air heated and coke 43/4 31/4 10  60
3. With air heated and coals not coked 21/4 31/4 71/2 65

"Notes.—1st. To the coals stated in the second and third lines, must be added 5 cwt. of small coals, required to heat the air.

"2d. The expense of the apparatus for applying the heated air will be from 200l. to 300l. per furnace.

"3d. No coals are now coked at the Clyde Iron Works; at all the three furnaces the iron is smelted with coals.

"4th. The three furnaces are blown by a double-powered steam engine, with a steam cylinder 40 inches in diameter, and a blowing cylinder 80 inches in diameter, which compresses the air so as to carry 21/2 lbs. per square inch. There are two tuyeres to each furnace. The muzzles of the blow-pipes are 3 inches in diameter.

"5th. The air heated to upwards of 600° of Fahrenheit. It will melt lead at the distance of three inches from the orifice through which it issues from the pipe."

(289.) The increased effect produced by thus heating the air is by no means an obvious result: and an analysis of its action will lead to some curious views respecting the future application of machinery for blowing furnaces.

Every cubic foot of atmospheric air, driven into a