THE BLAST-FURNACE.
In our improved charcoal hot-blast furnaces three cords of dry oak or pitch-pine wood will produce a ton of pig metal; but in the cold-blast furnace, with the same degree of perfection in mechanical construction, and the same skill in conducting the operations, five cords of wood are required to produce the ton of iron.
In France, where great economy is practised in the use of fuel, one ton of charcoal produces a ton of pig iron; while two tons, or double the amount, of charcoal are re quired to elaborate the pig metal into bar iron,—requiring, thus, three tons of charcoal to each ton of merchant bar.
The proportion is rather less when mineral coals are used. Two tons of coal—mostly bituminous—or coke are used to the ten of pigs produced; while only three tons, or one third more, are used to elaborate the pig metal into bar iron, being five tons to produce the merchant bar from the ore.
But in the ordinary charcoal blast-furnaces, taking the average of such in the Southern States, for instance, the production of iron is much less to the amount of fuel used. The best yield we
know of in Virginia and Alabama is about one ton of pig iron to five cords of wood; but, since the charring is done there in open pits, not more than thirty-three bushels of charcoal is obtained from a cord, or 165 bushels from the five cords of wood used. This, however, is the most favorable result: we have seen thirty cords of wood used to produce a ton of pig metal in Alabama; but from eight to ten cords to the ton of iron produced is about the average. To reduce the pig metal to bar, not less than ten ad ditional cords are used. Therefore, to produce bar iron from the ore, by the process of blast-furnace and bloomery, not less than an average of eighteen to twenty cords of wood, or about six hundred bushels of charcoal, per ton of bar iron produced, is required; which is double the quantity used in our improved furnaces, or in the furnaces of France, and considerable more than is used in the improved forges for producing iron direct from the ore.