The manufacture of iron is a science truly worth the consideration of the philosopher, for it is fraught with the most important consequences, considered either as a material of commerce, or the means to an end. In advancing manufactures and the progress of improvement, it has had an effect on civilization unequalled by any known product, gold not excepted; for no substitute exists for iron, or ever did. No doubt the ancients had their bronze, of which they could form edge tools, even razors; but that was a very limited use of cutting tools: enough, perhaps, for war or subsistence, but not for the progress of the arts. Of the first discovery and use of iron we have no record; though its value may be presumed from the fact, that Quintus Curtius mentions that “Alexander of Macedon, received a present from Porus, an Indian chief, of about 30 lbs. weight of steel.” If this were a present fit for the conqueror of the world, its value, even at that early date, must have been great indeed. For many centuries, up to the sixteenth, all iron was produced by the aid of wood charcoal; and with such contracted and limited means, it was found that not more than 50 per cent, of the metal contained in the ore was extracted; consequently at this day all the ancient deposits of _slag_ are sought for and re-smelted, yielding a handsome return to the manufacturer. The adoption of coal coke was a matter of necessity, but it has been productive of extensive benefit in all manufactures of iron of medium quality. The opinions of many men of science lead to the belief that it has benefited the higher quality also; but I am quite satisfied of the reverse. The quantity formerly obtained in the yield was, as shown, only 50 per cent. of the quantity existing in the ore; but yet it was the purest metal: for it is unquestionable that the best is soonest fused. The iron ore of Great Britain is, beyond a doubt, inferior to that of many parts of the world; as all attempts to produce good steel from it have been attended ultimately with disappointment. Mr. Mushet, in his excellent work on iron, says, “The successful exertions of individuals have increased the manufacture of cast and malleable iron beyond all precedent in this country; nor have we been without some enlightened individuals, who have laudably endeavoured to form a superior quality along with the extension of their manufactures. Success has so far crowned their praiseworthy exertions, aided by the operation of knowledge, in removing the prejudices of the artisan, that bar iron of our own manufacturing has been substituted, to a great extent, in place of that formerly used of the Swedish and Russian marks; but hitherto all attempts have failed to make bars of proper quality to form steel, in any degree comparable to that we daily manufacture in great quantities from foreign iron.