MECHANICS AND USEFUL ARTS. 93 



Unite, an ore of iron containing manganese. This iron was far more 

 tenacious and fibrous than the best Swedish, bending readily double, 

 in some instances, where the Swedish broke short off. 



S3IELTING MAGNETIC IRON ORES. 



THE Journal of the Franklin Institute, for February, contains a 

 paper by Mr. H. Fairbairn, on " smelting magnetic iron ores." The 

 author states that these ores of iron are found in New Jersey, Penn- 

 sylvania, New York, Maryland, Virginia, South Carolina, and many 

 of the Southwestern States, but are most known, in a manufacturing 

 point of view, in New Jersey and Pennsylvania, especially on the 

 bunks of the Lehigh. They are the richest of all the ores of iron, being 

 not only productive of iron in the greatest quantities, but the iron 

 is of very fine quality. In this country great difficulty has been ex- 

 perienced in smelting this species of ore without adding an admixture 

 of hematite, a poorer variety, and though one or two furnaces have at 

 times smelted the ore pure, the damage to the furnace was found to 

 be so great that the attempt was soon abandoned, so that it is gen- 

 erally considered that it is not practicable to smelt the magnetic oxide 

 of iron, with profit to the manufacturer, unless with the admixture of 

 considerably more than one half of the inferior hematite ore. But 

 this admixture deteriorates the quality of the metal, and is fatal to any 

 competition with Russian iron. 



It is therefore of great importance to overcome this difficulty ; and 

 that it can be overcome is shown by the fact, that iron equal to the 

 Russian, produced from the magnetic ores, is from time to time ex- 

 hibited in this country. The author thinks that the waste of lime- 

 stone in the smelting-furnace is one of the leading causes of the un- 

 successful attempts to produce iron for steel from the magnetic ores 

 of the Lehigh, and urges that, if the earthy ingredients in the ores be 

 only 10 per cent., 1 cwt. of limestone is the true quantity to be used 

 in the smelting-furnace. Another important error is the filling the 

 furnaces with the ores in an insufficiently reduced state. This variety 

 of iron ore, being of great specific gravity, naturally tends to fall 

 through and below the coals, the limestone and the other ores in the 

 furnace at the same time lying impressed against the boshes, obstruct- 

 ing the blast, impeding its own reduction, and causing much of the 

 superincumbent coal to be lost to the process of smelting and wasted 

 at the tunnel-head. The remedy for this is to be found in reducing 

 the magnetic ores to the smallest size, and also in filling the furnace 

 with the ores more intimately mixed with the limestone and the coals. 



The internal form of the furnaces on the Lehigh, which is cylindri- 

 cal, is another impediment to the successful smelting of these heavy 

 ores, which press with great force, owing to their increased weight, 

 against the walls of a furnace with an imperfect internal curve. The 

 Stanhope furnaces, where the magnetic ores are smelted without any 

 admixture of hematite, are true circles. The author thinks there can 

 be no truth in the usual reasoning of the proprietors of iron-works, 

 that the use of the hot-blast is the cause of the difficulty in the pro- 

 duction of iron for the purposes of steel 



