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about four feet of ore or over. The strata bearing these three veins is about two hundred yards in thickness—that is from the upper to the lower vein; the middle one being about equidistant from each. Their dip here, as at Bloomsburg, is north and south, from the saddle; no basin having as yet been discovered, though it has been asserted that the north dip of the south basin has been discovered on the south side of the Susquehanna at Danville, and . specimens of rich magnetic ore shown as samples--one of which I have; but the more experienced are inclined to doubt it, and geologists flatly contradict it, because if it does exist, in the magnetic state, it would puzzle them to reconcile it to their theories. With much truth and some philosophy, the school-boy cries, “What goes up must come down." But with coal and iron veins the case is reversed, for when they go down they are sure to come up. With such a theory, which is more of a fact than a theory—the iron seams of this region would present two distinct basins; one to the south, and the other to the north of Montour Ridge. The distance from crop to crop of the basins must be from one to two miles, and on the saddles, though the upper vein crops ont, and in some places the south and the north crop of it is from a half to a mile distant, the underlying veins do not appear to daylight, but overlap the saddle and continue the course without coming to daylight, except in the ravine or gorges of the mountain, where they are plainly discernible.
The strike of the veins are nearly uniform here with that of the coal seams to the south, and the same as that of the same veins in Columbia County, which is within a few points of east and west, extending from Briar Creek, above Bloomsburg on the east, to Hollidaysburg on the west, as it is supposed. A vast field of ore is here presented, equal in proportion to the anthracite coalfields of the State, and admirably situated in regard to the facilities for mining —with every convenience in prospect, for obtaining the requisite material for manufacturing, and for transportation to ever ready markets.
Limestone of the purest quality is found as close to the furnaces as it could be desired, and in quantities commensurate with the vast amount of ore to which it is so important an auxiliary, and which lies so conveniently near.
The quantity of coal now made use of in the manufacturing of iron in this region, cannot be much less than 200,000 tons yearly, besides the large amount which is used for other purposes, and it would be no groundless assertion to state that 1860 would demand 1,000,000 tons of coal from the Shamokin and Wyoming regions, to be delivered on the river from Shickshinny to Sunbury, on the North Branch, and from Sunbury to Williamsport on the West Branch. Danville, 1856.
S. H. D.
In addition to the preceding, we append the following analyses of the ores of the same county :-
The anthracite furnaces of Columbia, Montour, Northumberland and Union Counties, use the fossil ore of Montour Ridge, and obtain their coal from the Wilkesbarre region. The ore of Montour Ridge presents several interesting characters, and produces several grades of cold short iron. The suface ore, and from those strata which have been affected by the percolation of water, are porous, work more easily in the furnace than the compact varieties, and afford an iron with less silica. The compact silicious and calcareous varieties are comparatively refractory, and when used alone, generally produce a silicious cold short iron. This is particularly the case withi furnaces having low stacks, and that drive a too heavy blast. In general, the anthracite iron of this region is particularly adapted to neutralize the peculiar and most general properties of other anthracite pig, red shortness which is imparted by sulphur, where the presence of phosphorus does not counteract its influence.
The following are analyses of the fossil ores of Montour Co., Pa., as given by Mr. Boye, for Prof. Henry D. Rogers' Geological Report, 1841 :
By the above we may see that no mention is made of the important and generally present elements-phosphorus and sulphur. As the analyses of sin. gle specimens can rarely give an adequate knowledge of the composition of the bulk of the ore, it is prudent to examine those constituents, the presence of which is obvious from other considerations. Fossil remains of shells or other bony structures, we can safely presunie to contain phosphate of lime; and crystals of pyrites afford indubitable evidence of the presence of sulphur. The qualities of the iron produced also, afford, a great extent, evidences of the presence of certain elements, either in the ore, flux, or fuel; and without much trouble, as a general fact, the material containing the elements may be designated. This subject opens too wide a field of remarks for a full examination in this connection. To show more clearly what we consider as a proper statement of the composition of the ores of Montour Ridge, we give the following table, estimated from the analyses of Mr. Boye, and from the wellknown composition of minerals disseminated through the ores, and from the properties of the iron and the comparative yield in smelting:
Average proportions of iron 35 per cent. in hard, and 44 per cent. in soft.
EXPERIMENTS WITH OAST METALS.
A work has recently appeared under the authority of the Secretary of War, which contains some valuable reports of officers belonging to the U. S. Ordnance Department, in relation to experiments made with cast metals:
The experiinents were extended over a series of years, and were made to test the strength and other properties of metals employed in the manufacture of cannon. The work is a scientific one of great value, especially the information it contains relating to the nature and treatment of cast-iron, a material of deep interest to so many millions of people in our own and other countries.
The experiments were mostly conducted under the charge of Major W.
Wade, who details them in an exceedingly clear and interesting manner. One new fact developed by them is, that iron fused a number of times up to a certain point, is thereby greatly improved in strength. In trials with some iron it was found that its transverse strength was nearly doubled by being melted and cast four times. This is a discovery of great importance to all engineers and cast-iron founders. At the South Boston foundry, experiments were made to test the strength of cast-iron which bad been submitted to fusion during different periods of time. Eleven thousand pounds of iron were cast into four six-pounder guns: one after the metal had been under fusion or melted half an hour; the second, under fusion an hour and a half; the third, under fusion three hours; and the fourth, under fusion three hours and three quarters. The gun tirst cast burst at the thirty-first fire; the second, at the thirty-fourth; the third was fired thirty-eight times, and remained unbroken. Thus the strength of the metal seemed to increase in a ratio corresponding to the period of fusion, or under which it was kept in a highly molten state, and it might have been inferred from this that the fourth gun would have been the strongest of all. Instead of this being so, however, it proved to be the weakest, for it burst at the twenty-fifth discharge. In view of these experiments, Major Wade, in this report, says: “these results appear to establish satisfactorily the fact, that a prolonged exposure of liquid iron to an intense heat, does augment its cohesive power, and this power increases as the time of the exposure up to some (not well ascertained) limit, beyond which the strength of the iron is diminished.” This is a new developed fact in relation to castiron, subject to concussions, of deep import to all engineers. Experiments were also made to test the transverse strength of cast iron bars, two inches square and twenty-four inches long, the metal of which was kept under fusion during different periods of time. These bars were set on supports twenty inches apart, and the breaking force was applied at the middle. The results obtained from four castings were in favor of that which was kept fused longest --three hours. On this head the report says, " from this it appears that the cohesive power of the iron, so far as it can be shown by its capacity to resist transverse strains, is increased 60 per cent. by its continued exposure in fusion.” This is also a fact of importance to engineers and architects, regarding girders and beams, subject to a crushing force.
In most of the books which treat of the strength of cast-iron, the resistance which it opposes to certain strains is given ; but little useful information can be obtained in them regarding the very great difference of strength in different kinds of cast iron. But as the density between the lower and higher grades of this metal differs as 6.9 to 7.4a difference of 31 pounds per cubic foot, and as the tenacity of the metal has a relationship to its density, it was found by these experiments that cast iron, having a density of 6,900, had only a tenacity of 9,000; while that having a density of 7,400, had a tenacity of 45,970.
Castings of the greatest weight, according to their size, are by far the strongest, and weighing them is a ready means of judging comparatively of their strength.
Some important facts were also developed in relation to the cooling of heavy castings. At the Fort Pitt Iron Works, two eight-inch and two teninch guns were cast, one of each in the common way, solid, and one of each with a core on a tube of iron, through which water was inade to circulate after casting, to cool it from the interior, according to an invention of Lieut. Rodman. The solid eight-inch gun burst at the seventy-third discharge; the hollow cast one stood 1,500 discharges, and did not burst; the solid ten-inch cast gun stood only twenty fires, while the hollow ten-inch gun stood 249. These guns were cast of the same material and at the same time, the difference in favor of the hollow cast guns is astonishing. This is attributed to the method of cooling, it being supposed that in cooling, the solid guns contract entirely from the outside, and that a strain is exerted upon the arrangement of the particles of the metal, in the same direction as the strain of the discharges.
Lieut. Rodman goes into a very subtle mathematical demonstration to show that this is the case, and that his method of cooling the casting obviates this unequal strain. But on the back of this, Major Wade presents a new fact in relation to the effect of time after the castings are made, and before they are used, which is also of vast importance to engineers. Eight-inch guns proved thirty days after being cast solid, stood but 72 charges; a gun of the saine bore, proved thirty-four days after being cast, stood 84 charges, while one which was proved one hundred days after being cast, stood 731 charges, and another, proved after being cast six years, stood 2,582 charges. What ini important fact is thus newly developed, showing us that solid cast iron shoul. not be actively used until they have been kept for some years. Major Wada accounts for this phenomenon in cast-iron, by supposing that the particles strained in the cooling re-adjust themselves in the course of time to their new position, and become free or nearly so, and he presents some good arguments in favor of this theory.
The lesson to be derived from this by our engineers is, that heavy castings of iron for beams and machinery, subject to strains, are less capable of resisting them immediately after being cast; in other words, old castings are much stronger than new iron castings.
THE MANUFACTURE OF STEEL,
The method by which steel is manufactured is in its leading principle generally known. The interest in this pursuit must greatly increase in this country, and a statement somewhat in detail of the process of its manufacture may be instructive to many of our readers. Preparations are making to use the Lake Superior iron extensively for this purpose.
It has been clearly demonstrated that the Lake Superior iron can be converted into steel of the finest and best quality; and the Sharon Iron Co. of Pennsylvania, which owns the Sharon Iron Mountain of Lake Superior, is making preparations for entering extensively into its manufacture, intending to convert all their iron from Lake Superior into steel. The success of this enterprise (and there is no reason to doubt it) will form a new era in American manufactures, and give increased value and importance to Lake Superior iron, as no other kind in this country has been found capable of making steel that would at all compare with Swedes, English, Russia and Madras. Indeed, in Great Britain there is only one kind of iron, the Wolverstone charcoal, that can be converted into good steel; and with that exception, nearly all steel manufactured in England is made from Madras, Swedes and Russia iron.
Steel is iron passed through a process called cementation, the object of which is to impregnate it with carbon. Carbon exists more abundantly in charcoal than in any other fusible substance, and the smoke that goes up from a charcoal forge is carbon in a fluid state. Now, if you can manage to confine that smoke, and put a piece of iron into it for several days, and heat the iron at the same time, it will become steel. Heating the iron opens its pores, so that the smoke or carbon, enters into it.
The furnace for this purpose is a conical building of brick, in the middle of which are two troughs of brick or stone, which hold about four tons of bar iron. At the bottoin is a large grate for the fire. A layer of charcoal dust is put upon the bottom of the troughs, then a layer of bar iron, and so on alternately, until the troughs are full. They are then covered over with clay to keep ont the air, which, if admitted, would prevent the cementation. Fire is then communicated to the wood and coal with which the furnace is filled, and continued until the conversion of the iron into steel is completed, which generally happens in about eight or ten days. This is known by the blisters on the bars, which the workinen occasionally draw out, in order to determine when the conversion is completed. The fire is then left to go out, and the
bars remain in the furnace about eight days to cool. This is called " blistered steel.” German steel is made of this blistered steel, by breaking the bars into short pieces, and welding them together, drawing thein down to a proper for nse.
Blistered steel when reduced into smaller bars, and beaten under heavy hammers, forms what is termed “tilted steel.” The building in which the operation is performed is called "a tilt" on account of the workmai, when holding a bar of steel sitting in a kind of cradle suspended from the roof, and swinging to and fro as he thrusts or "tilts” the bar under the hammer. The word “ tilt,” as applied to this action, and to the rise and fall of the hammer, is of Saxon origin-implying to thrust at, and also to vacillate, or to move up and down.
Tilted steel, when broken, heated, welded, and again forged into bars, is known as “ shear steel," from the circumstance of its universal employment in the manufacture of the best shears for sheep-shearing.
English cast steel is another variety of this protean compound of iron and carbon, and is obtained by melting steel with vitrifiable matter and charcoal, then casting it into the form of ingots, which are subseqnently gently heated, and carefully hammered or rolled into the form of smaller bars.
Blistered steel and cast steel contains 98 to 99 per cent. of iron; the remaining portion consists of carbon.
Tempering Steel.–Steel which has been rendered excessively hard and brittle by heating to redness and suddenly quenching in water, admits of having its hardness reduced, and of acquiring elasticity by a process called " tempering.". This admits of the following illustrations:
Let three strips of elastic steel, of equal length and breadth, and thickness, be placed on a clear glowing fire; when they become equally red-hot, remove two of them with a pair of tongs, and drop them into cold water ; then remove the third and place it upon the hearth to cool.
Take one of the suddenly quenched strips and attempt to bend it by the strength of the hands; it will not bend but break short, and will scratch glass; so that the steel by this treatment becomes exceedingly brittle and hard.
Take the strip that has slowly cooled down upon the hearth; it will bend with the same facility as a similar sized strip of copper would bend; and, like it, will keep the form into which it is bent, and will not scratch glass, so that the steel by this treatment bas become extremely flexible and soft.
Lastly, take the remaining strip of suddenly quenched steel, polish one of its surfaces with emery paper, then let the end of a large iron poker be heated bright red-hot, and afterwards be supported horizontally upon a brick or tile, placed on a table near the light; lay the strip of steel, with its polished surface uppermost, on the red-hot poker in the direction of its length; in the course of a few seconds the steel will present a curious display of colors, commencing with a straw tint, which gradually deepens to a brown, next to red, with streaks of purple, and ultimately to fine blue; let it be removed and allowed to cool. When cold it will be found to bend with readiness, and to fly back to its original straight form when the bending force is removed. It admits of being scratched with a piece of the brittle, hard strip; so that by this treatment the steel bas become less hard than it was, and also regains its elasticity, or technically, it has acquired “spring temper."
The colors that appear upon sieel, during the process of tempering, depend upon its iron sustaining slight oxidation, and is therefore rendered capable of decomposing light and of reflecting some of its chronic rays, or their mixtures; for when polished steel is heated out of the contact of the air, it retains its peculiar lustre and only reflects white light, yet it becomes perfectly tempered to any required extent.
The chemist has accurately determined the degree of heat by which steel may be suitably tempered for various implements, and has communicated another important fact to the artisan, that mercury may be heated to any degree short of its boiling point, so that a thermometer introduced into it will denote