Bog iron

“ Magnetite is not unknown in several of the remoter parts of Scotland, but the distance from fuel has hitherto prevented its application to economic purposes, at least in modern times. Bog iron ore, an hydrated oxide of iron still more readily fused, is also common in Sweden, and abundant in the northern and western islands of Scotland ”

“ Bog-iron is to be found wherever the land is bleak and barren, and hundreds of tons of it are shipped annually to England, where it is used instead of lime for the purification of gas. Along the shores of Lough Swilly a light blue clay is found about forty feet above the present sea-level: it contains numerous fragments of shells, and seems to mark the old sea-beach. Bog is the surface deposit on a large portion of the county, and in some places it is as much as twenty feet deep, with trees occurring abundantly in it. ”

“ In Norway and Sweden there are large and important deposits of bog iron-ore, which have presumably been formed in the beds of lakes.
Fig. 53.
Cainozoic Ironstone with Leaves (Banksia ? marginata, Cavanilles) .
Slightly enlarged. Below Wannon Falls, Redruth, Victoria.
Clay ironstone nodules (sphaerosiderite) have generally been formed as accretions around some « 81 » decaying organic body. Many clay ironstone nodules, when broken open, reveal a fossil within, such as a coprolitic body, fern frond, fir-cone, shell or fish. ”

“ The ores are first formed in the hydrated condition, and then lose their water by metamorphic agencies, becoming specular and magnetic, or the state in which the Laurentian irons are now known. Ores of iron are conceived to have been formed under similar conditions in all ages. At the present day they accumulate in swamps and low grounds in the condition of the hydrated peroxide (ferric) , or bog-ore, oftentimes in company with manganese. The presence of organic vegetable matter is requisite in order to extract the iron from the rock or soil and effect its deposition. ”

“ Bog-ore, to be spoken of as bog ore, is abundant, and manganese is known to exist in large quantities. Soapstone of excellent quality is also plentiful, and the peasantry will tell you that on the passing of the Home Rule Bill they will at once proceed to dig out the inexhaustible stores of gold, silver, lead, iron, tin, and coal, with which the district abounds. ”

“ On the application of heat in furnaces, constructed for the purpose, the charcoal unites with the oxygen of the oxide, reducing it to the metallic state, and escapes in the form of carbonic acid; and the lime, if the ore be argillaceous, unites with the clay, forming a kind of glass, which floats on the melted metal. When the iron is suffered to run into moulds, prepared for its reception, it usually takes the name of pig iron.
Manufacturers distinguish cast iron by its colour and other qualities. The white cast iron is hard and brittle, and can neither be filed, bored, nor bent. ”

“ As a commercial product, such as is used in the arts and manufactures and by the smith, it is always combined with other substances, such as carbon, silicon, and phosphorus.
Iron is distributed through the earth very widely, but not always in sufficient quantities to make its extraction from the ore profitable; consequently the ores used for the extraction of iron are somewhat limited. There are four general grades of iron ore, which are known by the following names: magnetite, red hematite, limonite, and ferrous carbonate. ”

“ Up to that time cast-iron was converted into wrought-iron by heating it with charcoal and exposing the melted metal to a blast of air. By this process only small quantities of wrought-iron were obtained at a time, through the necessity of producing but one bloom in a heat, which might easily be hammered out; and also on account of the cost of charcoal. In this process mineral coal could not be placed in contact with the iron, because the never-failing presence of sulphur in that kind of coal would render the iron unfit for use. ”

“ When the iron is present as bicarbonate, it acts on soap solutions like the analogous lime and magnesia compounds, producing even worse results. In wool scouring, cotton bleaching, and other processes requiring the use of alkaline carbonates, ferric oxide is precipitated on the fibre. A yellowish tinge is communicated to bleached fabrics, and to dye bright and light colours is rendered almost out of the question. You may always suspect iron to be present in water flowing from or obtained directly out of old coal pits, iron mines, or from places abounding in iron and aluminous shales. ”

“ It is so, and that is one of its worst properties. Every liquor, and even a moist air corrode it. But the rust of iron is not pernicious: on the contrary, it is a very useful medicine.
Geo. I have heard of steel drops and steel filings given for medicine.
Tut. Yes; iron is given in a variety of forms, and the property of them all is to strengthen the constitution. Many springs are made medicinal by the iron that they dissolve in the bowels of the earth. These are called chalybeate waters, and they may be known by their inky taste, and the rust-coloured sediment they leave in their course. ”

“ Wrought iron will occasion scintillations, somewhat of the same appearance, and steel, also, in greater abundance; and hence both are employed in sundry compositions. But the particular character, beauty, and brilliancy of Chinese fire must be attributed, first to the iron, and secondly to its peculiar state of combination with carbon and oxygen; for, we have said, that malleable iron, (which is deprived in a great measure of these substances in the operation required for its preparation) , produces an effect far inferior to cast iron. ”

“ Age or time dries, consumes, undermines and reduces to ashes, no less than fire; indeed with an action far more subtle; but because such motion is very sluggish, and acts on particles very small, the heat is not perceived. It is also shown by comparing the dissolution of iron and gold. Gold is dissolved without any heat being excited, while the dissolution of iron is accompanied by a violent heat, though it takes place in about the same time. The reason is that in gold the separating acid enters gently and works with subtlety, and the parts of the gold yield easily ”

“ Pig-iron, or, as it is sometimes called, crude iron, being saturated with carbon and oxygen, and containing also a portion of scoria, is too brittle for any other purpose than castings. Many of these, such as stoves, grates, mill-irons, plough-irons, and kitchen utensils, are commonly manufactured at blast furnaces, and in many cases nearly all the iron is used for these purposes. In such cases, the metal is taken in a liquid state, from the hearth, in ladles. ”

“ Descending underground waters charged with oxygen have decomposed the iron carbonate and deposited the iron, in the form of iron oxide, in troughs of the strata where their downward progress was arrested by impervious floors.
The pre-Cambrian rocks of the eastern United States also are rich in iron. In certain districts, as in the Highlands of New Jersey, the black oxide of iron (magnetite) is so abundant in beds and disseminated grains that the ordinary surveyor’s compass is useless. ”

“ Avicenna, in his fifth book De Animâ, according to Roger Bacon, distinguishes three very different species of iron: “1st. Iron which is good for striking or bearing heavy strokes, and for being forged by hammer and fire, but not for cutting-tools. Of this hammers and anvils are made, and this is what we commonly call Iron simply. 2nd. That which is purer, has more heat in it, and is better adapted to take an edge and to form cutting-tools, but is not so malleable, viz. Steel. And the 3rd is that which is called Andena. This is less known among the Latin nations. ”

“ The latter salt, under the combined influence of hydrogen and heat, is reduced to metallic iron, which assumes the appearance of a fine black powder. When the experiment is completed the glass vessel is closed, and the iron, thus protected from contact with the air, can be preserved indefinitely; but if it is exposed to the air by breaking off the end of the receptacle (fig. 311) , it ignites immediately, producing a shower of fire of very beautiful effect. Iron thus prepared is known under the name of pyrophoric iron. Iron is acted upon in a very powerful manner by most acids. ”

“ During the melting of the charge the heat is kept as high as possible and the molten iron is “puddled,” i. e., stirred, by the “puddler” or his helper with a “rabbler” or iron bar. In order to take out the phosphorus and sulphur, which for best results should be removed before the carbon is eliminated, the heat of the furnace is lowered somewhat as soon as all of the pig has melted, and some iron oxide is mixed into the “bath” of molten iron and cinder. Most of the phosphorus and sulphur are chemically acted upon and pass into the cinder which covers the iron. ”

“ Prescott, “just remember three things: fuel, blast, and hammer—power, of course, behind the hammer. It’s the different variations that men have been making on those three things that have brought iron where it is to-day.
“Iron ore has so many things besides iron in it that the problem has always been how to get the impurities out.
“The old blacksmiths used to put it in the fire and hammer it; put it back in the fire and hammer again, until they worked most of the other things out. They made what is called forge iron. ”

“ That, heated by the bricks, is forced into the furnace.
“One of those great pipes up there is where they draw off the slag. It is so much lighter than the iron that it rises to the top, like cream on milk.
“Down here they draw off the iron. Sometimes they keep it hot for the next process; sometimes it is made into pig iron.”
“What,” asked Dr. Crandon, “becomes of the slag?” ”

“ It is so highly 75refined that it can hardly be called steel at all but is often called “open-hearth iron” or “ingot iron.” It is probably the purest iron on the market in commercial quantities to-day. While in the chemical laboratory iron of considerably greater purity can be made, for a commercial product this is remarkably pure, seldom containing more than 1⁄4 per cent of elements other than the metal, iron. ”

“ The metal was costly and scarce, and hence one of the most obvious sources of the lengthened period over which we have seen reason to believe that the Archaic era extended. Throughout that whole period metal in every form was a rare and valued luxury, and it was as such that iron, the most widely diffused, the most abundant and most useful of all the metals, was first introduced into the British Isles. This is sufficiently accounted for from the fact, that iron rarely, if ever, occurs in nature in a metallic state; and that it requires great labour and a most intense heat to fuse it. ”

“ One has no difficulty in realizing that these flakes, which cut in every direction through the metal, make it structurally weak, especially toward a sudden blow.
No. 1d shows a typical section of wrought iron cut lengthwise of the rolled bar. It will be noted that, as in photomicrograph No. 99b, there are no graphite flakes.
In the process of wrought iron manufacture practically all of the carbon of the original pig iron is burned out, leaving little besides the iron itself and some viscous cinder or slag. ”

“ Pure iron like pure gold is homogeneous, but unlike gold it is rarely pure. If gold be kept in a melted condition a sufficiently long time, all extraneous matters may be burnt away, but if iron be kept in a hot state too long it will be burnt away itself. Pure iron appears to be ductile, but pure iron will not melt. To form cast-iron, a quantity of carbon must be mixed with the pure iron. If the quantity of carbon be less in amount, steel is the result. ”

“ The pig iron contains from 2 to 5 per cent of carbon, which it obtains from the coal in the blast-furnace, and it is this particular proportion of carbon which gives it its own peculiar properties. To convert it into wrought iron a workman puts a long iron rod into the furnace and stirs the metal about, thereby exposing it to the air and permitting the carbon to be burnt out. As it loses carbon the iron becomes less and less fluid until it reaches a sticky stage. ”

“ Peat-bogs do not wholly consist of peat, and nothing else. The trunks of such trees as the oak, yew, and fir, are often found mingled with the remains of mosses and reeds, and these often assume a decidedly coaly aspect. From the famous Bog of Allen in Ireland, pieces of oak, generally known as "bog-oak," which have been buried for generations in peat, have been excavated. These are as black as any coal can well be, and are sufficiently hard to allow of their being used in the manufacture of brooches and other ornamental objects. ”

“ Prescott; “we might ask the wrong questions.”
“Then, Billy Bradford,” said Mr. Farnsworth, smiling at Billy, “I’ll explain to you, and the others may listen.
“You see we chemists analyze the ores before they are smelted; so we know something about what kind of pig iron we shall have. But when we want to know what kind of finished iron or steel we have from a given process, we can’t tell much by analyzing it, so we have to depend on our microscopes.
“Metals crystallize, if they have just the right conditions. Each metal has its own form ”