Page:The American Cyclopædia (1879) Volume IX.djvu/425

Rh available either for mining purposes or the manufacture of charcoal iron. Passing westward, in Arkansas and Missouri is reached that wonderful range of red oxide of iron, which, in mountains rising hundreds of feet above the surface, or in beds beneath the soil, culminates at Lake Superior in deposits of ore which excite the wonder of all beholders; and returning thence to the Atlantic slope, in the Adirondacks of New York, is a vast undeveloped region, watered by rivers whose beds are of iron, and traversed by mountains whose foundations are laid upon the same material; while in and among the coal beds themselves are found scattered deposits of hematite and fossiliferous ores, which, by their close proximity to the coal, have inaugurated the iron industry of our day. From these vast treasures the world may draw its supply for centuries to come, and with these the inquirer may rest contented, without further question; for all the coal of the rest of the world might be deposited within this iron rim, and its square miles would not occupy one quarter of the coal area of the United States.” The table on the preceding page gives analyses of various ores from different localities, indicated by numbers as follows: A. Hematites. 1. Whitehaven, Cumberland, England. 2. Iron mountain, Missouri; specular ore from vein. (The phosphoric acid is the average of four determinations in as many samples, varying from 0.252 to 0.081 per cent.) 3. Pilot Knob, Missouri; specular ore from main ore bed. B. Hydrous Hematites. 4. Lake ore, Sweden. (Phosphoric acid varies from 0.051 to 1.213 per cent.) 5. Katahdin furnace, Piscataquis co., Me., resulting from the decomposition of iron pyrites. 6. Silicious ore, York co., Pa. 7. Pennsylvania furnace ore-bank, Centre co., Pa. C. Carbonates. I. Spathic ore. 8. Müsner Stahlberg, Prussia. 9. Calcined spathic ore from Altenberg, Styria, used for Bessemer process at Neuberg. 10. Brendon hill, Somersetshire, England. II. Earthy carbonates. 11. Gubbin ironstone, Dudley, S. Staffordshire, England. 12. Sphærosiderite from Ahaus, Prussia. 13. Eston, Cleveland, England; main seam. 14. Carbonate ore from Fayette co., Pa. III. Blackband. 15. Shelton, N. Staffordshire, England. 16. Westphalian blackband, low grade. 17. Best Westphalian, roasted. D. Magnetites. 18. Dannemora ore, Sweden. 19. Granrot ore, Sweden. 20. Lake Champlain, “new bed” ore, unusually free from apatite. 21. A sample from New Hope mine, Morris co., N. J. (The ores in northern New Jersey are very variable in regard to silica and phosphoric acid. The former varies from 2 to 40 per cent., the latter from 0 to 3 per cent. Low percentages of both silica and phosphoric acid, and freedom from sulphur, are usual.) 22. Titaniferous, from Greensboro, N. C. The following table shows the amount of sulphur and phosphorus contained in most of the Swedish and in some of the Prussian ores:

—Treatment of Ores. Iron ores are generally used in the blast furnace in the condition in which they are mined, but sometimes they are submitted to a preliminary treatment. The carbonate ores are invariably roasted before smelting. This drives off the carbonic acid; the ferrous is converted into magnetic oxide; and the ore is rendered not only richer but much more porous, and thereby more readily reduced. Ores containing much sulphur are also roasted with access of air, and the greater part of the sulphur is driven off as sulphurous acid. Heavy compact ores are occasionally roasted to render them friable. Roasting may be effected in open heaps or within brick walls by piling the ore and fuel (wood or brush) in layers, and allowing it to burn out. This method is far less thorough and efficient than roasting in shaft furnaces. In the latter case the fuel (small coal) and ore may be charged alternately, or gas (from the blast furnace or suitable generators) may be used. The operation is continuous. Brown hematites often occur mixed largely with clay and other earthy matters; they are then submitted to a dressing or concentrating process by washing, in which the lighter clay is washed off and the heavier ore remains.—Forge and mill cinders, produced in puddling and heating iron, are very rich in iron, containing from 40 to 75 per cent. Although, strictly speaking, they are not ores of iron, yet they are used for reduction in the blast furnace. Their use in large quantity is attended with disadvantage, owing to the facility with which they melt and escape reduction. Puddling cinder, moreover, contains the greater part of the impurities of the iron from which it is made, and yields therefore inferior iron. Roasting renders the cinder more infusible, and also effects a partial purification.  IRONS, William Josiah, an English clergyman and author, born at Hoddesden, Hertfordshire, Sept. 12, 1812. He graduated at Queen's college, Oxford, in 1833, was some time a curate in the suburbs of London, afterward vicar of Barkway, Hertfordshire, and of Brompton, Middlesex, and in 1860 was made prebendary of St.