Coal in a Geological point of view Coal in a Mining point of view Mineralogical Characters of Coal Coal in a Chemical point of view Arnott's Smoke-consuming and Fuel-saving Fireplace Review of the Whale Fishery for 1850.-Annual Report Detection of Sulphuretted Hydrogen and Bisulphide of Carbon in A GROUP I. THE BRANCHES OF MANUFACTURE CONNECTED WITH THE PRODUCTION OF FUEL AND THE PROCESS OF COMBUSTION. EVERY person who has directed his attention to the necessary conditions for carrying on any branch of manufacturing industry, will have learnt at the outset that heat and the powerful effects produced by its agency, take precedence of all others. It is impossible to name any manufacture in which either an elevated temperature or the power obtained by means of that temperature, are not employed in some part of the process. Even agriculture, the most backward of all the arts, is gradually substituting steam power for performing those operations in which manual dexterity has hitherto been employed; and small steam-engines are springing up on every farm of consequence in the North of England and Scotland, which will no doubt increase in number with a knowledge of scientific principles and the necessity for saving labour in that all-important art, and in a few years, the production of corn and beasts, in short of food generally, will VOL. I. 1 stand as much in need of artificial heat as the economical production of cotton fabrics, iron, or any of the chemical or metallurgical products of our island. These latter departments of industry, however, are entirely dependent upon the agency of heat, and, generally speaking, of an intense heat. It is therefore of importance to every one connected with these arts, to acquire a knowledge of the sources of heat, and the chemical and physical laws concerned in its production, so as to apply this invaluable agent in the manner best suited to the object in view and with the greatest amount of profit and economy. Every substance possessing the property of burning in the air, that is of combining with its oxygen with the evolution of light and heat, might be employed as a heating agent, but of the numerous combustible bodies which nature supplies, few are found in sufficient quantity to be generally applicable to the production of artificial heat. These few, however, are so abundant and so generally diffused, that no inhabited country is entirely devoid of one or other of them; indeed, so essential is artificial heat, in some form or other, to human existence, that no country totally without the means of producing it, would be habitable for any length of time. The wealth and manufacturing ascendancy of this country depend in a great measure on the abundant supply of one of the richest sources of artificial heat lying buried in the earth, in her coal-fields. England had but small influence in the councils of Europe until these were discovered and turned to full account by the indomitable industry and enterprise of her inhabitants; and without so invaluable an accessory to the acquirement of wealth and power, her commercial fate and fame might soon have sunk to a level with those of Venice or of Holland. FUEL. The substances to which allusion has been made above, and which we collectively call Fuel, are: 1. wood; 2. peat or turf; 3. brown-coal or lignite; 4. pit-coal or coal; 5. wood-charcoal; 6. peat-charcoal; 7. coke from brown-coal and coal, certain combustible gases, and artificial fuel. The first four are natural productions, and the others are obtained from them by important manufacturing processes. The whole of these substances are more or less closely allied to wood or woody fibre, from which they have all originally been derived, and all are indebted for their combustible properties to the carbon and hydrogen of which they are essentially composed. These two elements, together with oxygen and small quantities of nitrogen, water and inorganic salts (ash) compose the entire mass of the natural fuels; and their relative value depends in a great measure upon the proportions in which the two former elements enter into their composition. Most of the artificial fuels contain carbon as the essential ingredient; the other elements, with the exception of the ash, having been expelled in the processes of manufacture. The value of fuel is diminished by the ash, which is not combustible; and the sulphur and phosphorus sometimes present are peculiarly prejudicial in some of its applications. The facility with which fuel is ignited and continues to burn, depends much upon its chemical constitution and the porosity of its texture. A large amount of hydrogen is generally favourable to rapid ignition; this element separates, in combination with a portion of carbon, as carburetted hydrogen, at a temperature below redness, and surrounds the remainder of the fuel with an atmosphere of combustible gas in full ignition, which causes the combustion to spread. The portion of carbon which is not burnt in the form of gaseous carbo-hydrogen, is left by the escape of the gas in such a very porous state, that atmospheric oxygen easily obtains access, and the whole is consumed. The property of burning with flame is thus intimately connected with the presence of hydrogen in the combustible, and the artificial fuels which contain no hydrogen, only produce flame when an insufficient quantity of air is directly supplied to them for the production of carbonic acid, carbonic oxide is then generated, which may again be ignited in contact with more air. Wood, peat and some kinds of brown and gas coals produce the longest flame; they contain the largest amount of hydrogen, and are most easily decomposed. Coal is not generally so inflammable, and some varieties, as anthracite, burn without flame, like charcoal and the other artificial fuels. These distinctions are important in many applications of fuel. Where the materials to be heated are separated from the combustible, an inflammable fuel must be selected, the greatest heat being then found at the extremity of the flame; great local intensity of heat is obtained, so to speak, on the other hand, in immediate contact with those kinds of fuel which are consumed without flame. WOOD. The trunk, roots, and larger branches of trees are all called wood. The other parts, leaves, twigs and small branches, called brushwood, are likewise used as fuel, and differ from the more solid portions in the proportions of the several constituents to be mentioned hereafter, and in the inflammability and heating power which they exhibit; but as these form a very small proportion of the wood employed as fuel, it is unnecessary to specify these differences more minutely than is done in the subsequent table, showing the elementary composition and amount of ash in some of the more important. Wood is composed of three different substances: first, woody fibre, a combination of carbon, hydrogen, and oxygen, which forms the cells and vessels of the plant, and makes up the chief part of its bulk; second, the constituents of the sap contained in the vessels; and last, water. Recently felled wood necessarily contains all three constituents. The two first only are supporters of combustion, and produce heat; the water, on the contrary, whilst the wood is burning, is converted into vapour at the expense of a portion of the heat. As woody fibre and water are common to all kinds of wood, the difference which has been shown to exist between different woods must entirely depend upon the constituents of their sap, and upon their structure (density). Notwithstanding the great difference, chemically speaking, in the constituents of the sap, (the coniferous woods containing resinous matter; the beech and birch, extractive; and the oak, tannin); the accurate analysis of dried woods has shown that they contain the three elementary constituents, carbon, hydrogen, and oxygen, nearly in the same proportions as pure woody fibre, so that the constituents of the sap must form a very small proportion of the whole bulk of the wood, and their action cannot materially alter the value of the wood as fuel, although it becomes very perceptible when the wood is applied to certain practical purposes, as in the process of tanning.. The amount of water in wood has greater influence, and is of much more importance, as it materially influences its calorific power. Water is generally most abundant in wood at the time of the flow of the sap, and least, |