CLASS 1. Mining and Mineral Products. are becoming every day of greater importance. They are found, both as veins traversing the beds of the mountain limestone formation, transversely to the lines of stratification, and also as beds more or less regular. The former is the general character of the Ulverstone and Furness ores, no clearly defined bed being, as yet, known in that district, whilst at Whitehaven there are two, if not more beds of irregular thickness, but with clearly defined floors and roofs, and oftentimes sub-divided themselves by regular partings. These beds attain a considerable thickness, occasionally 20 or 30 feet. The area over which they extend is not as yet well known; but they have been worked extensively for many years, and the workings upon them are rapidly increasing. They lie beneath and close to the coal measures, which both furnishes the necessary fuel, and also important beds of argillaceous ironstones for admixture. Annual production of iron about 30,000 tons. The ores of the Forest of Dean are Carboniferous, or Mountain Limestone ores, lying beneath the coal measures, which are not here productive in argillaceous ironstones as in the other principal coal-fields of the kingdom. Besides the limestone ore, there is a bed of ore in the Millstone Grit measures; but which is only worked very locally. The limestone ore occupies a regular position in the limestone measures, although in itself exceedingly irregular, assuming rather the character of a series of chambers than a regular bed. These chambers are sometimes of great extent, and contain many thousand tons of ore, which is generally raised at an exceedingly low cost, no timbering or other supports for the roof being required. The supply of ore producible in the Forest of Dean is almost unlimited. The iron made from it is of a red short nature, and especially celebrated for the manufac ture of tin plates. Its superior quality always commands a high price. This ore is raised extensively for shipment to the iron works of South Wales. It was worked at a very ancient date either by the Romans or the Britons, as is evident from the remains of old workings along the outcrop of the ore bed. This ore averages from 30 to 40 per cent. General No. of No. Series. 439 1 440 2 441 3 442 4 443 5 Geological Formation: Granite and the Older Rocks. Compact Micaceous Iron Ore, Hennock, Devon.-Found in lodes varying from 1 to 12 feet wide, bearing east and west. These lodes are in coarse-grained porphyritic granite. The ore is associated with Quartz, Clay, Schorl, and Hornblende. It contains 60 cent. Soft Micaceous Iron Ore, Hennock.-Found associated with No. 1. Magnetic Oride, Haytor, Devon.-Found inter-stratified with a compact Feldspathic and Horblende Slate. It is associated with Asbestos, Actynolite, Garnet, Opal, Quartz, and Clay. It contains 70 per cent. Compact Brown Iron Ore, Bishopsteignton, Devon.-Found in irregular masses, in Limestone. It contains 60 per cent. Compact and Crystallized Brown Iron Ore, Brixham, Devon.-Found in irregular masses, in Limestone. It contains 55 per cent. 6 Rel Hematite, Sheviock, Cornwall.-Found in lodes in Clay Slate. 444 445 7 Brown Hæmatite, Sheviock, Cornwall. Ft. In These iron ores have at different periods, been worked to a considerable extent for transport to South Wales. They are of inferior quality; but the large masses in which they lie, enable them to be raised at a very trifling expense. They are found at Tremadoc, Pwllheli, Carnarvon, Island of Anglesea, and many other localities round the North Welsh Coast; and will doubtless at some period, prove of importance, from the great extent to which they are there developed. General No. of No. Series. Ft. In CLASS 1. Mining and Mineral Products. These specimens are of great interest, as belonging to the formation which was formerly one of our principal sources of iron; but which, furnishing with its ores no fuel to smelt them, was abandoned, upon the exhaustion of its forests, by the iron trade for the coalfields, where all the requisites for this manufacture exist. Perhaps, like the lias of Whitby, &c., the Green Sand of Sussex may again, by means of railroads, at no distant period, furnish the iron trade with additional supplies of this important ore. AN ACCOUNT OF THE NATURE AND EXTENT OF THE VARIOUS DEPOSITS OF MINERAL FUEL IN VARIOUS PARTS OF THE WORLD. Accompanied by a map, showing the extent and position of the principal coal-fields of Europe and North America. By D. T. ANSTED, M.A., F.R.S., &c., Prof. Geol., K.C.L. 1. General Account of Materials used for Fuel. The chief source of supply of valuable fuel is, and always has been, derived immediately or distantly from the vegetable kingdom. Whether in the form of wood, peat, lignite, or coal of various kinds, the original substance of all fuel has been found to have this origin, and thus it would seem that the power of vitality exerted in producing woody fibre has been from time to time stored up, as it were, into vast reservoirs, where it might be preserved safely and permanently for an indefinite period. In warm climates, where the growth of vegetation is extremely rapid, and comparatively little fuel is needed: or in the early periods of civilization, before men congregate in large masses in towns, or are actively employed in manufacture: there is little need of more fuel than is supplied by the natural growth of forests; but under other circumstances, where forests are gradually removed, and the consumption of fuel at the same time increases, the reserved stores are greatly needed, and must ultimately be reckoned among the main sources of a country's wealth. The accumulations of mineral fuel in the British islands may be ranked as one of those natural advantages, without which our country could not possibly have taken up, and held for a long time the position she occupies among the nations of the earth, and thus, as one of great and principal sources of its mineral treasure, the coal deposits of England demand and deserve our careful attention. The relative supply of other countries, and the activity and energy displayed in taking advantage of the existence of mineral fuel, must also be worthy of attention, as illustrating and explaining the condition of many manufactures, and the probable advance of the inhabitants of such districts in the refinements of civilization. Since the introduction of steam-power for all purposes of machinery, the consumption of coal has very greatly increased, and at present it would be difficult to set any limits to the use of so valuable a material. The changes undergone by vegetable matter when buried in the earth and accumulated in large quantities, and the length of time needed to produce any marked alteration, are subjects rather interesting, it may seem, to the chemist than to the practical man, who looks only for fuel that he may employ economically. But inasmuch as the real condition of coal varies considerably, and different kinds are valuable for different purposes, it is desirable that the whole history of coal and lignite beds, and of peat and turf, should be generally understood by every one using any or all of these substances extensively. Vegetable matter consists of particles of carbon with minute proportions of several other elements arranged round minute cavities or cells, many of these being mechanically connected to form the varieties of vegetable fibre. A large quantity of water is also present, and so long as the vegetable lives there is a constant change and circulation of material particles kept up, replacing and renewing the different portions. When death takes place there is a tendency to decomposition, or the sepa ration of the whole into minute atoms, having no further relation to each other. But this is frequently checked by various conditions, such as the presence of some substances derived from plants themselves, or the absence of sufficient oxygen gas to allow the change to take place, by mixing with the carbon, and becoming carbonic acid gas, the first step in the process of destruction. These causes operate constantly, but partially, and thus a large quantity of vegetable matter is always in the course of decomposition, while, in particular spots, a large quantity is constantly being accumulated. The latter condition is seen in our climate in the gradual but steady increase of peat bogs. The former is too common to require further notice. 2. Peat and Turf. Accumulations of vegetable matter may be chiefly composed either of succulent vegetation, grasses, or marsh plants, or of trees, and the structure and condition of woody fibre is well known to be very different from that of grasses and succulent plants. There are thus two very distinct kinds of material preserved, the one undergoing change much less rapidly than the other, and perhaps much less completely. It is easy to prove that, from the accumulation of forest trees has been obtained the imperfect coal called lignite, while from marsh plants and grasses, mixed occasionally with wood, we obtain peat, turf, and bog. All these substances consist to a great extent of carbon, the proportion amounting to from 50 to 60 per cent., and being generally greater in lignite than in turf. On the other hand, the proportion of oxygen gas is generally very much greater in turf than in lignite. The proportion of ash is too variable to be worth recording, but is generally sufficiently large to injure the quality of the fuel. As a very large quantity of turf exists in Ireland, covering, indeed, as much as one-seventh part of the island, the usual and important practical condition of this substance as fuel can be best illustrated by a reference to that country. This will be understood by the following account of its origin abstracted from the Bog Report" of Mr. Nimmo. He says, referring to cases where clay spread over gravel has produced a kind of puddle, preventing the escape of the waters of floods or springs, and when muddy pools have thus been formed, that aquatic plants have gradually crept in from the borders of the pool towards their deep centre. Mud accumulated round their roots and stalks, and a spongy semi-fluid was thus formed, well fitted for the growth of moss, which now, especially spears of Sphagnum, began to luxuriate; this absorbing a large quantity of water, and continuing to shoot out new plants above, while the old were decaying, rotting, and compressing into a solid substance below, gradually replaced the water by a mass of vegetable matter. In this manner the marsh might be filled up, while the central or moister portion, continuing to excite a me rapid growth of the moss, it would be gradually ra above the edges, until the whole surface had attained elevation sufficient to discharge the surface-wate existing channels of drainage, and calculated by its to facilitate their passage, when a lim”) degree, set to its further increase. the bog, or in its immediate vici favour its growth, though in here, if the water proceeding CLASS 1. Mining and Mineral Products. structed as to accumulate at its base, and to keep it in a rotten fluid state, the surface of the bog might be ultimately so raised, and its continuity below so totally destroyed, as to cause it to flow over the retaining obstacle, and flood the adjacent country. In mountain districts the progress of the phenomenon is similar. Pools, indeed, cannot in so many instances be formed, the steep slopes facilitating drainage, but the clouds and mists resting on the summits and sides of mountains, amply supply their surface with moisture, which comes, too, in the most favourable form for vegetation, not in a sudden torrent, but unceasingly and gently, drop by drop. The extent of such bogs is also affected by the nature of the rock below them. On quartz they are shallow and small; on any rock yielding by its decomposition a clayey coating, they are considerable; the thickness of the bog (for example in Knocklaid, in the county of Antrim, which is 1,685 feet high) being nearly 12 feet. The summit bogs of high mountains are distinguishable from those of lower levels, by the total absence of large trees. As turf includes a mass of plants in different stages of decomposition, its aspect and constitution vary very much. Near the surface it is light-coloured, spongy, and contains the vegetable matter but little altered; deeper it is brown, denser, and more decomposed; and finally, at the base of the greater bogs, some of which present a depth of 40 feet, the mass of turf assumes the black colour, and nearly the density of coal, to which also it approximates very much in chemical composition. The amount of ash contained in turf is also variable, and appears to increase in proportion as we descend. Thus, in the section of a bog 40 feet deep, at Timahoe, those portions near the surface contained 14 per cent. of ashes, the centre portions 3 per cent., whilst the lowest four feet of turf, contained 19 per cent. of ashes. In the superficial layers, it may also be remarked, that the composition is nearly the same as that of wood, the vegetable material being but little altered, and in the lower we find the change into coal nearly complete. Notwithstanding these extreme variations, we may yet establish the ordinary constitution of turf with certainty enough for practical use, and, on the average specimens of turf selected from various localities, the following results have been obtained : The calorific power of dry turf is about half that of coal; it yields, when ignited with litharge, about fourteen times its weight of lead. This power is, however, immensely diminished in ordinary use, by the water which is allowed to remain in its texture, and of which the spongy character of its mass renders it very difficult to get rid. There is nothing which requires more alteration than the collection and preparation of turf; indeed, for practical purposes, this valuable fuel is absolutely spoiled as it is now prepared in Ireland. It is cut in a wet season of the year; whilst drying it is exposed to the weather; it hence is in reality not dried at all. It is very usual to find the turf of commerce containing one-fourth of its weight of water, although it then feels dry to the hand. But let us examine how that affects its calorific power. One pound of pure dry turf will evaporate 6 lbs. of water; now in 1 lb. of turf, as usually found, there are lb. of dry turf, and 14 lb. of water. The lb. can only evaporate 4 lbs. of water; but out of this it must first evaporate the lb. contained in its mass, and hence the water boiled away by 1 lb. of such turf is reduced to 44 lbs. The loss is here 30 per cent., a proportion which makes all the difference between a good fuel and one almost unfit for use. When turf is dried in the air, under cover, it still retains one-tenth of its weight of water, which reduces its calorific power 12 per cent., 1 lb. of such turf evaporating 5 lbs. of water. This effect is sufficient, however, for the great majority of objects; the further desiccation is too expensive and too troublesome to be used, except in some especial cases. The characteristic fault of turf as a fuel is its want of density, which renders it difficult to concentrate within a limited space the quantity of heat necessary for many operations. The manner of heating turf is, indeed, just the opposite to that of anthracite. The turf yields a vast body of volatile inflammable ingredients, which pass into the flues and chimney, and thus distribute the heat of combustion over a great space, whilst in no one point is the heat intense. Hence for all flaming fires turf is applicable, and in its application to boilers it is peculiarly useful, as there is no liability to that burning away the heat of coke or coal. If it be required, it is quite of the metal, which may arise from the local intensity of possible, however, to obtain a very intense heat with turf. The removal of the porosity and elasticity of turf, so that it may assume the solidity of coal, has been the object of many who have proposed mechanical and other processes for the purpose. It has been found that the elasticity of the turf fibre presents great obstacles to copression, and the black turf, which is not fibrous, is, of itself, sufficiently dense. tion, or compressed, or impregnated with pitchy matter, Not merely may we utilize turf in its natural conditurf charcoal, the properties of which it is important to but we may carbonize it, as we do wood, and prepare establish. The methods of carbonization are of two loss is avoided, but it is expensive, and there is no comkinds :-1. By heating turf in close vessels; by this mode pensation in the distilled liquors, which do not contain acetic acid in any quantity. The tar is often small in quantity, and the gases are deficient in illuminating power, hence the charcoal is the only valuable product. Its quantity varies from 30 to 40 per cent. by weight of the dry turf. The products of the distillation of 1,157 lbs. of turf were found by Blavier to be-charcoal, 474 lbs., or 41 per cent. ; watery liquid, 226 lbs., or 19-3 per cent.; gaseous matter, 450 lbs., or 39 per cent.; and tar, 7 lbs., or 6 per cent.; but the proportion of tar is variable, sometimes reaching to 24.5 per cent. when coked in close vessels. The economical carbonization of turf is best carried on in heaps, in the same manner as that of wood. The sods must be regularly arranged, and laid as close as possible; they are the better for being large-15 inches long, by 6 broad, and 5 deep. The heaps, built hemispherically, should be smaller in size than the heaps of wood usually are. In general 5,000 or 6,000 large sods feet. The mass must be allowed to heat more than is may go to a heap, which will thus contain 1,500 cubic carefully attended to, from the extreme combustibility necessary for wood, and the process requires to be very of the charcoal. The quantity of charcoal obtained in this mode of carbonization is from 25 to 30 per cent. of the weight of dry turf. mable; it possesses nearly the volume of the turf. It Oxygen and nitrogen 1.70 4.20 4.20 100.00 For many industrial uses the charcoal so prepared is too light, as, generally speaking, it is only with fuels of considerable density that the most intense heat can be produced; but by coking compressed turf, it has been already shown, that the resulting charcoal may attain a density of 1,040, which is far superior to that of wood charcoal, and even equal to that of the best coke made from coal. As to calorific effect, turf charcoal is about the same as coal cokes, and little inferior to wood charcoal. It is peculiarly important, in the preparation of the charcoal from turf, that the material should be selected as free as possible from earthy impurities, for all such are concentrated in the coke, which may be thereby rendered of little comparative value. Hence the coke from |